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1
Marinescu, N., i M. Apostol. "Quantum-Mechanical Concepts in the Waveguides Theory". Zeitschrift für Naturforschung A 47, nr 9 (1.09.1992): 935–40. http://dx.doi.org/10.1515/zna-1992-0902.
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Abstract A Klein-Gordon-type equation is derived for the wave propagation in an ideal, uniform waveguide, and its quantum-mechanical interpretation is given. The "cross-section" concept is introduced for a waveguide and the power transmission factor is obtained by using standard methods of quantum mechanics. The spinorial formalism is also employed for deriving the equivalent Dirac-type equation, and the perturbation theory is applied for computing the frequency shifts. The general applicability of the quantum-mechanical concepts to the waveguides theory is discussed
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Renno, Jamil, Niels Søndergaard, Sadok Sassi i Mohammad R. Paurobally. "Wave Scattering and Power Flow in Straight-Helical-Straight Waveguide Structure". International Journal of Applied Mechanics 11, nr 08 (wrzesień 2019): 1950075. http://dx.doi.org/10.1142/s1758825119500753.
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The knowledge of wave scattering and power flow in waveguide structures is important for many engineering applications. In this paper, power flow and scattering in a straight-helical-straight waveguide structure are investigated using the wave and finite element (WFE) method. For simple (straight or helical) waveguides, wave scattering (and subsequently the power flow and scattering) can be resolved analytically. This is not the case for complex waveguides such as laminated or sandwiched waveguides or waveguides with noncanonical cross-sections. In such cases, the WFE method is used to model the wave behavior in each waveguide in the structure. The power flow is then studied by considering how waves reflect and transmit at the boundaries that join the straight waveguides with the helical waveguide. We present three numerical examples but analytical solutions can be obtained for the first example only; for the second and third examples, the WFE is used in earnest since the wave behavior and subsequently the power flow would at best be extremely difficult to formulate analytically.
3
Chandra, Veer, i Rakesh Ranjan. "Design and Analysis of Micro-Opto-Mechanical System Cantilever Integrated with Photonics Waveguide for Pressure Sensing Applications". Sensor Letters 18, nr 1 (1.01.2020): 18–25. http://dx.doi.org/10.1166/sl.2020.4178.
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In this work, the pressure sensing approach based on the Micro-Opto-Mechanical System (MOMS) cantilever integrated with waveguide structure has been explored. The MOMS based photonic sensors are drawing attention because of their high sensing capabilities. In the design of MOMS based cantilever pressure sensor, mainly two different waveguide structures, Rib and Slot waveguides have been considered. The deviation in light intensity at the output of the waveguide structure is mainly used to analyze the amount of exerted pressure at the free-end of cantilever. Using the different waveguide parameters such as, effective mode area, light intensity variations, etc., the performance comparison between Rib and Slot waveguides have been done. The relationship between the normalized light intensity at the waveguide output corresponding to the applied pressure has been established from the relationship between the deflection versus pressure and normalized intensity versus deflection. It has been anticipated that the performance of pressure sensor using Slot waveguide is significantly better than the Rib waveguide for some application.
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Su, Xiao-Xing, Zi-Long Dou i Heow Pueh Lee. "Stimulated Brillouin scattering in a sub-wavelength anisotropic waveguide with slightly-misaligned material and structural axes: misalignment-sensitive behaviors and underlying physics". Journal of Optics 24, nr 4 (7.03.2022): 045002. http://dx.doi.org/10.1088/2040-8986/ac432b.
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Abstract The stimulated Brillouin scatterings (SBSs) in sub-wavelength rutile waveguides with slightly misaligned material and structural axes are numerically studied. The misalignment is introduced between the extraordinary material axis and longitudinal axis of the waveguide only. Four nanowire waveguides with different cross-sectional geometries are considered. They consist of a circular waveguide, two elliptical waveguides with different cross-sectional orientation angles, and a trapezoidal waveguide with a completely unsymmetrical cross-sectional shape. As previously reported, the resonant peaks emerge rapidly in response to the introduced small misalignment angle and can also be observed in the calculated Brillouin gain spectra of the considered waveguides. But these misalignment-sensitive resonant peaks further exhibit some extraordinary behaviors, which may not be intuitively understandable. For instance, despite a plausible absence of symmetry breaking, many misalignment-sensitive resonant peaks can still be observed in the forward SBS gain spectrum of the trapezoidal waveguide. Based on the symmetry properties of the considered waveguides, the physics underlying the observed extraordinary phenomena are revealed. The obtained results highlight the effectiveness of introducing symmetry breakings for activating/harnessing opto-mechanical couplings in photonic-phononic micro structures, which would enable us to gain some deeper insights into the sub-wavelength opto-mechanics in anisotropic media.
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Čehovski, Marko, Jing Becker, Ouacef Charfi, Hans-Hermann Johannes, Claas Müller i Wolfgang Kowalsky. "Single-Mode Polymer Ridge Waveguide Integration of Organic Thin-Film Laser". Applied Sciences 10, nr 8 (18.04.2020): 2805. http://dx.doi.org/10.3390/app10082805.
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Organic thin-film lasers (OLAS) are promising optical sources when it comes to flexibility and small-scale manufacturing. These properties are required especially for integrating organic thin-film lasers into single-mode waveguides. Optical sensors based on single-mode ridge waveguide systems, especially for Lab-on-a-chip (LoC) applications, usually need external laser sources, free-space optics, and coupling structures, which suffer from coupling losses and mechanical stabilization problems. In this paper, we report on the first successful integration of organic thin-film lasers directly into polymeric single-mode ridge waveguides forming a monolithic laser device for LoC applications. The integrated waveguide laser is achieved by three production steps: nanoimprint of Bragg gratings onto the waveguide cladding material EpoClad, UV-Lithography of the waveguide core material EpoCore, and thermal evaporation of the OLAS material Alq3:DCM2 on top of the single-mode waveguides and the Bragg grating area. Here, the laser light is analyzed out of the waveguide facet with optical spectroscopy presenting single-mode characteristics even with high pump energy densities. This kind of integrated waveguide laser is very suitable for photonic LoC applications based on intensity and interferometric sensors where single-mode operation is required.
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Zeng, Desheng, Qiang Liu, Chenyang Mei, Hongwei Li, Qingzhong Huang i Xinliang Zhang. "Demonstration of Ultra-High-Q Silicon Microring Resonators for Nonlinear Integrated Photonics". Micromachines 13, nr 7 (21.07.2022): 1155. http://dx.doi.org/10.3390/mi13071155.
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A reflowing photoresist and oxidation smoothing process is used to fabricate ultra-high-Q silicon microring resonators based on multimode rib waveguides. Over a wide range of wavelengths near 1550 nm, the average Q-factor of a ring with 1.2-μm-wide waveguides reaches up to 1.17 × 106, with a waveguide loss of approximately 0.28 dB/cm. For a resonator with 1.5-μm-wide waveguides, the average Q-factor reaches 1.20 × 106, and the waveguide loss is 0.27 dB/cm. Moreover, we theoretically and experimentally show that a reduction in the waveguide loss significantly improves the conversion efficiency of four-wave mixing. A high four-wave mixing conversion efficiency of −17.0 dB is achieved at a pump power of 6.50 dBm.
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Barbin, Evgenii, Tamara Nesterenko, Aleksei Koleda, Evgeniy Shesterikov, Ivan Kulinich i Andrey Kokolov. "An Optical Measuring Transducer for a Micro-Opto-Electro-Mechanical Micro-g Accelerometer Based on the Optical Tunneling Effect". Micromachines 14, nr 4 (31.03.2023): 802. http://dx.doi.org/10.3390/mi14040802.
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Micro-opto-electro-mechanical (MOEM) accelerometers that can measure small accelerations are attracting growing attention thanks to their considerable advantages—such as high sensitivity and immunity to electromagnetic noise—over their rivals. In this treatise, we analyze 12 schemes of MOEM-accelerometers, which include a spring mass and a tunneling-effect-based optical sensing system containing an optical directional coupler consisting of a fixed and a movable waveguide separated by an air gap. The movable waveguide can perform linear and angular movement. In addition, the waveguides can lie in single or different planes. Under acceleration, the schemes feature the following changes to the optical system: gap, coupling length, overlapping area between the movable and fixed waveguides. The schemes with altering coupling lengths feature the lowest sensitivity, yet possess a virtually unlimited dynamic range, which makes them comparable to capacitive transducers. The sensitivity of the scheme depends on the coupling length and amounts to 11.25 × 103 m−1 for a coupling length of 44 μm and 30 × 103 m−1 for a coupling length of 15 μm. The schemes with changing overlapping areas possess moderate sensitivity (1.25 × 106 m−1). The highest sensitivity (above 6.25 × 106 m−1) belongs to the schemes with an altering gap between the waveguides.
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Khonina, Svetlana N., Grigory S. Voronkov, Elizaveta P. Grakhova, Nikolay L. Kazanskiy, Ruslan V. Kutluyarov i Muhammad A. Butt. "Polymer Waveguide-Based Optical Sensors—Interest in Bio, Gas, Temperature, and Mechanical Sensing Applications". Coatings 13, nr 3 (3.03.2023): 549. http://dx.doi.org/10.3390/coatings13030549.
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In the realization of photonic integrated devices, materials such as polymers are crucial. Polymers have shown compatibility with several patterning techniques, are generally affordable, and may be functionalized to obtain desired optical, electrical, or mechanical characteristics. Polymer waveguides are a viable platform for optical connectivity since they are easily adaptable to on-chip and on-board integration and promise low propagation losses <1 dB/cm. Furthermore, polymer waveguides can be made to be extremely flexible, able to withstand bending, twisting, and even stretching. Optical sensing is an interesting field of research that is gaining popularity in polymer photonics. Due to its huge potential for use in several industries, polymer waveguide-based sensors have attracted a lot of attention. Due to their resilience to electromagnetic fields, optical sensors operate better in difficult situations, such as those found in electrical power generating and conversion facilities. In this review, the most widely used polymer materials are discussed for integrated photonics. Moreover, four significant sensing applications of polymer-waveguide based sensors which include biosensing, gas sensing, temperature sensing and mechanical sensing have been debated.
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Lv, Jing, Razvan Stoian, Guanghua Cheng i Kedian Wang. "Index Modulation Embedded in Type I Waveguide Written by Femtosecond Laser in Fused Silica". Micromachines 12, nr 12 (18.12.2021): 1579. http://dx.doi.org/10.3390/mi12121579.
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Slit-shaped laser beams focused in bulk optical materials can realize embedded waveguides with circular cross sections consisting of positive index change type I traces. In these kinds of waveguide traces, a peculiar periodical refractive index modulation was observed in type I waveguides with two different femtosecond lasers. The direction of refractive index modulation can be controlled with the slit configuration, and its period can be controlled by mechanical perturbation of the stages and the scanning speed. We argue that platform perturbation and dynamical thermal transport processes during the scan are generating factors in the appearance of this modulation. The embedded microstructures in waveguides can provide spectrum modulation, which may have potential applications in optical sensing, filtering, and phase control.
10
Marinescu, Nicolae, i Rudolf Nistor. "Quantum Features of Microwave Propagation in a Rectangular Waveguide". Zeitschrift für Naturforschung A 45, nr 8 (1.08.1990): 953–57. http://dx.doi.org/10.1515/zna-1990-0803.
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AbstractThe formal analogy between the distribution of the electromagnetic field in waveguides and microwave cavities and quantum mechanical probability distributions is put into evidence. A waveguide of a cut-off frequency ωc acts on an electromagnetic wave as a quantum potential barrier Ug = hωc. A non-habitual time independent Schrödinger equation, describing guided wave propagation, is established
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Bhardwaj, Rakesh Kumar, H. S. Sudhamani, V. P. Dutta i Naresh Bhatnagar. "Micromachining and Characterisation of Folded Waveguide Structure at 0.22THz". Journal of Infrared, Millimeter, and Terahertz Waves 42, nr 3 (25.01.2021): 229–38. http://dx.doi.org/10.1007/s10762-021-00767-w.
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AbstractThe demand of high-speed wireless communication has increased, which need the data rate to be in the order of Terabyte per second (Tbps) in the near future. Terahertz (THz) band communication is a key wireless communication technology to satisfy this future demand. This would also reduce the spectrum scarcity and capacity limitation of current wireless systems. Microfabricated Folded Waveguide TWTs are the potential compact sources of wide band and high-power terahertz radiation. This study primarily focuses on machining technology for THz waveguide components requiring ultra-high precision micromachining. Rectangular waveguides, especially Folded Waveguides (FW), are even more difficult to manufacture using conventional machining techniques due to their small size and very tight tolerances. The criticalities in micromachining of FW for 0.22 THz have been addressed in this article. Half hard free cutting Brass IS 319-H2 was used as a work material due to its electrical and mechanical properties. Waveguide size of 0.852 × 0.12 mm was machined within ± 3–5 μm linear tolerances, surface roughness in the order of 45 nm Ra, and flatness less than half of wavelength (< λ/2). The split top and bottom blocks of the folded waveguide were aligned by dowel pins which matched within a tolerance of ± 5 μm. The perpendicularity and parallelism were maintained within 5 μm tolerance. This work explored and established the application of micromilling as reasonably suitable for the THz waveguides followed by ultrasonic cleaning as deburring. It also investigated the measured folded waveguide losses which were close to simulated values.
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Gill, Parvinder K., i Dan M. Marom. "Single Mode, Air-Cladded Optical Waveguides Supported by a Nano-Fin Fabricated with Direct Laser Writing". Applied Sciences 11, nr 14 (8.07.2021): 6327. http://dx.doi.org/10.3390/app11146327.
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Single-mode, air-cladded optical waveguides have wavelength scale diameters, making them very fragile and difficult to handle and yet highly desirable for sensing and inter-chip photonic interconnects. These contradictory qualities are resolved in this work by supporting the optical waveguide with a nano-fin structure attached to a substrate, narrow enough and sufficiently tall to minimally impact the wave-guiding metrics of the solid core while providing structural mechanical integrity. The design considerations for the nano-fin-supported waveguide and its realization using a commercial direct laser writing system based on two-photon activation of a photopolymer is reported herein. The 3D printed waveguides are characterized and experimentally assessed, demonstrating low birefringence and an estimated propagation loss for LP01x and LP01y of 2.9 dB/mm and 3.4 dB/mm, respectively, attributed to surface roughness and the relatively high refractive index contrast with air.
13
Zhi-Yong, Wang, Xiong Cai-Dong i He Bing. "Quantum mechanical description of waveguides". Chinese Physics B 17, nr 11 (listopad 2008): 3985–90. http://dx.doi.org/10.1088/1674-1056/17/11/008.
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Stell, J. D., i R. J. Bernhard. "Active Control of High Order Acoustical Modes in a Semi-Infinite Waveguide". Journal of Vibration and Acoustics 113, nr 4 (1.10.1991): 523–31. http://dx.doi.org/10.1115/1.2930217.
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This paper presents an analysis of the effectiveness of active noise control methods for control of high order modes in rigid-walled, semi-infinite waveguides. The waveguides examined in this investigation are terminated at one end with a rigid end. The case studies performed reconfirmed that n control actuators can control n propagating modes (including the plane wave) in a waveguide if the actuators are properly placed. The results also confirmed that the control actuators should be located at the node surfaces of the most significant evanescent modes to avoid various problems that evanescent modes cause active control systems. A significant new finding is the effect of the rigid waveguide termination on the active controller. The reflected energy from the termination causes standing waves in the region between the rigid termination and the secondary sources. At certain frequencies which correspond to resonant conditions, the standing wave amplitudes become large and the control actuator strength must be high. At these frequencies the effects of the evanescent modes become significant even when the mode is not close to its cut-on frequency. Similar resonant effects can be expected to affect active noise control performance for any case where there are significant reflections in the waveguide upstream of the control actuators.
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Deng, Xida, Ge Dong, Xuan Dai i Jinxiang Deng. "Compact Full Ka-Band Waveguide Directional Coupler Based on Rectangular Aperture Array with Stairs". Micromachines 12, nr 7 (25.06.2021): 745. http://dx.doi.org/10.3390/mi12070745.
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This article presents a compact 3 dB waveguide directional coupler with full waveguide bandwidth. It consists of a pair of rectangular waveguides with stairs structures in the coupling region. The waveguides are placed parallel to each other along their broad wall, which has a rectangular aperture array. The compact size, broad bandwidth, good in-band coupling flatness, and good return loss are achieved by using the proposed structure. For verification purposes, a prototype of the proposed coupler was designed, manufactured, and measured. The experimental results show that over the full waveguide bandwidth a return loss of input port better than 17.46 dB, coupling strength varying between −2.74 dB and −3.80 dB, power-split unbalance within 0.76 dB, and an isolation better than 20.82 dB were obtained. The length of the coupling region was only 15.82 mm.
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Qu, Yang, Yunyi Yang, Jiayang Wu, Yuning Zhang, Linnan Jia, Houssein El Dirani, Romain Crochemore i in. "Photo-Thermal Tuning of Graphene Oxide Coated Integrated Optical Waveguides". Micromachines 13, nr 8 (28.07.2022): 1194. http://dx.doi.org/10.3390/mi13081194.
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We experimentally investigate power-sensitive photo-thermal tuning (PTT) of two-dimensional (2D) graphene oxide (GO) films coated on integrated optical waveguides. We measure the light power thresholds for reversible and permanent GO reduction in silicon nitride (SiN) waveguides integrated with one and two layers of GO. For the device with one layer of GO, the power threshold for reversible and permanent GO reduction are ~20 and ~22 dBm, respectively. For the device with two layers of GO, the corresponding results are ~13 and ~18 dBm, respectively. Raman spectra at different positions of a hybrid waveguide with permanently reduced GO are characterized, verifying the inhomogeneous GO reduction along the direction of light propagation through the waveguide. The differences between the PTT induced by a continuous-wave laser and a pulsed laser are also compared, confirming that the PTT mainly depend on the average input power. These results reveal interesting features for 2D GO films coated on integrated optical waveguides, which are of fundamental importance for the control and engineering of GO’s properties in hybrid integrated photonic devices.
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Pons, Carolina, Josué M. Galindo, Juan C. Martín, Iván Torres-Moya, Sonia Merino, M. Antonia Herrero, Ester Vázquez, Pilar Prieto i Juan A. Vallés. "Propagation Losses Estimation in a Cationic-Network-Based Hydrogel Waveguide". Micromachines 13, nr 12 (18.12.2022): 2253. http://dx.doi.org/10.3390/mi13122253.
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A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption and scattering loss coefficients are determined for 450 nm, 532 nm and 633 nm excitation. The excellent optical loss values obtained (0.32–1.95 dB/cm), similar to others previously described, indicate their potential application as waveguides in different fields, including soft robotic and light-based therapies.
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Sharma, Kohli, Brière, Ménard i Nabki. "Translational MEMS Platform for Planar Optical Switching Fabrics". Micromachines 10, nr 7 (30.06.2019): 435. http://dx.doi.org/10.3390/mi10070435.
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While 3-D microelectromechanical systems (MEMS) allow switching between a large number of ports in optical telecommunication networks, the development of such systems often suffers from design, fabrication and packaging constraints due to the complex structures, the wafer bonding processes involved, and the tight alignment tolerances between different components. In this work, we present a 2-D translational MEMS platform capable of highly efficient planar optical switching through integration with silicon nitride (SiN) based optical waveguides. The discrete lateral displacement provided by simple parallel plate actuators on opposite sides of the central platform enables switching between different input and output waveguides. The proposed structure can displace the central platform by 3.37 µm in two directions at an actuation voltage of 65 V. Additionally, the parallel plate actuator designed for closing completely the 4.26 µm air gap between the fixed and moving waveguides operates at just 50 V. Eigenmode expansion analysis shows over 99% butt-coupling efficiency the between the SiN waveguides when the gap is closed. Also, 2.5 finite-difference time-domain analysis demonstrates zero cross talk between two parallel SiN waveguides across the length of the platform for a 3.5 µm separation between adjacent waveguides enabling multiple waveguide configuration onto the platform. Different MEMS designs were simulated using static structural analysis in ANSYS. These designs were fabricated with a custom process by AEPONYX Inc. (Montreal, QC, Canada) and through the PiezoMUMPs process of MEMSCAP (Durham, NC, USA).
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Zhang, Yuning, Jiayang Wu, Yunyi Yang, Yang Qu, Linnan Jia, Baohua Jia i David J. Moss. "Enhanced Spectral Broadening of Femtosecond Optical Pulses in Silicon Nanowires Integrated with 2D Graphene Oxide Films". Micromachines 13, nr 5 (11.05.2022): 756. http://dx.doi.org/10.3390/mi13050756.
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We experimentally demonstrate enhanced spectral broadening of femtosecond optical pulses after propagation through silicon-on-insulator (SOI) nanowire waveguides integrated with two-dimensional (2D) graphene oxide (GO) films. Owing to the strong mode overlap between the SOI nanowires and the GO films with a high Kerr nonlinearity, the self-phase modulation (SPM) process in the hybrid waveguides is significantly enhanced, resulting in greatly improved spectral broadening of the femtosecond optical pulses. A solution-based, transfer-free coating method is used to integrate GO films onto the SOI nanowires with precise control of the film thickness. Detailed SPM measurements using femtosecond optical pulses are carried out, achieving a broadening factor of up to ~4.3 for a device with 0.4-mm-long, 2 layers of GO. By fitting the experimental results with the theory, we obtain an improvement in the waveguide nonlinear parameter by a factor of ~3.5 and in the effective nonlinear figure of merit (FOM) by a factor of ~3.8, relative to the uncoated waveguide. Finally, we discuss the influence of GO film length on the spectral broadening and compare the nonlinear optical performance of different integrated waveguides coated with GO films. These results confirm the improved nonlinear optical performance of silicon devices integrated with 2D GO films.
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Rabii, Christopher D. "Mechanical properties of hollow glass waveguides". Optical Engineering 38, nr 9 (1.09.1999): 1490. http://dx.doi.org/10.1117/1.602261.
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Piotr, Kiełczyński, Marek Szalewski, Andrzej Balcerzak i Krzysztof Wieja. "Impact of losses on Love wave propagation in multilayered composite structures loaded with a Newtonian liquid". Journal of Vibration and Control 26, nr 23-24 (26.03.2020): 2221–29. http://dx.doi.org/10.1177/1077546320916041.
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In this study, we analyze theoretically and numerically the properties of Love surface waves propagating in lossy multilayered composite waveguides, loaded on the upper surface with a Newtonian liquid. The propagation of Love surface waves was formulated in terms of a direct Sturm–Liouville problem. An analytical form of the complex dispersion equation of the Love surface wave was derived using the Thomson–Haskell transfer matrix method. By separating the complex dispersion equation into its real and imaginary parts, we obtained a set of two nonlinear algebraic equations, which were subsequently solved numerically. The effect of various physical parameters of the lossy viscoelastic waveguide on the velocity and attenuation of the Love surface wave was then analyzed numerically. It was found that because of the presence of losses in the analyzed waveguide, Love surface waves displayed a number of new original phenomena, such as resonant-like maxima in attenuation as a function of thicknesses [Formula: see text] of the first viscoelastic surface layer and thickness [Formula: see text] of the second elastic surface layer. These phenomena are completely absent in lossless waveguides.
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Roland, Iännis, Marco Ravaro, Stéphan Suffit, Pascal Filloux, Aristide Lemaître, Ivan Favero i Giuseppe Leo. "Second-Harmonic Generation in Suspended AlGaAs Waveguides: A Comparative Study". Micromachines 11, nr 2 (23.02.2020): 229. http://dx.doi.org/10.3390/mi11020229.
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Due to adjustable modal birefringence, suspended AlGaAs optical waveguides with submicron transverse sections can support phase-matched frequency mixing in the whole material transparency range, even close to the material bandgap, by tuning the width-to-height ratio. Furthermore, their single-pass conversion efficiency is potentially huge, thanks to the extreme confinement of the interacting modes in the highly nonlinear and high-refractive-index core, with scattering losses lower than in selectively oxidized or quasi-phase-matched AlGaAs waveguides. Here we compare the performances of two types of suspended waveguides made of this material, designed for second-harmonic generation (SHG) in the telecom range: (a) a nanowire suspended in air by lateral tethers and (b) an ultrathin nanorib, made of a strip lying on a suspended membrane of the same material. Both devices have been fabricated from a 123 nm thick AlGaAs epitaxial layer and tested in terms of SHG efficiency, injection and propagation losses. Our results point out that the nanorib waveguide, which benefits from a far better mechanical robustness, performs comparably to the fully suspended nanowire and is well-suited for liquid sensing applications.
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Lei, Yuechen, Zhi-Gang Hu, Min Wang, Yi-Meng Gao, Zhanchun Zuo, Xiulai Xu i Bei-Bei Li. "Fully reconfigurable optomechanical add-drop filters". Applied Physics Letters 121, nr 18 (31.10.2022): 181110. http://dx.doi.org/10.1063/5.0114020.
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Fully reconfigurable add-drop filters (ADFs) have important applications in optical communication and information processing. Here, we demonstrate a broadly tunable add-drop filter based on a double-disk cavity optomechanical system, side-coupled with a pair of tapered fiber waveguides. We investigate the dependence of the through (drop) efficiency on coupling rates between the cavity and two waveguides by varying cavity-waveguide distances. By optimizing the cavity-waveguide coupling rates, a drop efficiency of 89% and a transmission of 1.9% have been achieved. Furthermore, tuning of the ADF is realized by changing the air gap of the double disk using a fiber tip, which is controlled by a piezoelectric nanostage. Benefiting from the large optomechanical coupling coefficient and the mechanical compliance of the double-disk microcavity, a tuning range of 8 nm has been realized using a voltage of 7 V on the piezoelectric nanostage, which is more than one free spectral range of the cavity. As a result, both the through and drop signals can be resonant with any wavelength within the transparent window of the cavity material, which indicates that the ADF is fully reconfigurable.
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Carlotto, Alice, Osman Sayginer, Anna Szczurek, Lam T. N. Tran, Rossana Dell’Anna, Stefano Varas, Bartosz Babiarczuk i in. "Flexible all-glass planar structured fabricated by RF-sputtering". EPJ Web of Conferences 266 (2022): 06003. http://dx.doi.org/10.1051/epjconf/202226606003.
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Flexible SiO2/HfO2 1D photonic crystals and active SiO2–HfO2:Er3+ all-glass flexible planar waveguides fabricated by radio frequency sputtering, are presented. The 1D photonic crystals show a strong dependence of the optical features on the light incident angle: i) blue-shift of the stopband and ii) narrowing of the reflectance window. Nevertheless, the most interesting result is the experimental evidence that, even after the 1D photonic crystals breakage, where the flexible glass shows naked-eye visible cracks, the multilayer structures generally maintain their integrity, resulting to be promising systems for flexible photonic applications thanks to their optical, thermal and mechanical stability. The flexible planar waveguides, fabricated on ultrathin flexible glass substrate, showed an attenuation coefficient lower than 0.2 dB/cm at 1.54 μm, and exibits emission in the NIR region, resulting particularly suitable as waveguide amplifier in the C band of telecommunications.
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Wang, Shang-Pu, Tien-Hsiang Lee, You-Yuan Chen i Pei-Hsun Wang. "Dispersion Engineering of Silicon Nitride Microresonators via Reconstructable SU-8 Polymer Cladding". Micromachines 13, nr 3 (17.03.2022): 454. http://dx.doi.org/10.3390/mi13030454.
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In this work, we propose a novel way to flexibly engineer the waveguide dispersion by patterning the cladding of waveguide microresonators. Experimentally, we demonstrate silicon nitride waveguides with air-, oxide-, and SU-8 polymer-cladding layers and compare the corresponding waveguide dispersion. By integrating SU-8 polymer as the outer cladding layer, the waveguide dispersion can be tuned from −143 to −257 ps/nm/km. Through the simple, conventional polymer stripping process, we reconstruct the waveguide dispersion back to that of the original air-cladded device without significantly impacting the quality factor of resonators. This work provides the potential to design the waveguide dispersion in normal and anomalous regimes within an integrated photonic circuit.
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Romero, Carolina, Javier García Ajates, Feng Chen i Javier R. Vázquez de Aldana. "Fabrication of Tapered Circular Depressed-Cladding Waveguides in Nd:YAG Crystal by Femtosecond-Laser Direct Inscription". Micromachines 11, nr 1 (19.12.2019): 10. http://dx.doi.org/10.3390/mi11010010.
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Crystalline materials are excellent substrates for the integration of compact photonic devices benefiting from the unique optical properties of these materials. The technique of direct inscription with femtosecond lasers, as an advantage over other techniques, has opened the door to the fabrication of true three-dimensional (3D) photonic devices in almost any transparent substrate. Depressed-cladding waveguides have been demonstrated to be an excellent and versatile platform for the integration of 3D photonic circuits in crystals. Here, we present the technique that we have developed to inscribe tapered depressed-cladding waveguides with a circular section for the control of the modal behavior. As a proof of concept, we have applied the technique to fabricate structures in Nd:YAG crystal that efficiently change the modal behavior from highly multimodal to monomodal, in the visible and near infrared, with reduction factors in the waveguide radius of up to 4:1. Our results are interesting for different devices such as waveguide lasers, frequency converters or connectors between external devices with different core sizes.
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Wu, Kai, i Marcel Tichem. "Post-Release Deformation and Motion Control of Photonic Waveguide Beams by Tuneable Electrothermal Actuators in Thick SiO2". Micromachines 9, nr 10 (27.09.2018): 496. http://dx.doi.org/10.3390/mi9100496.
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Photonic packaging, which includes high-precision assembly of photonic sub-systems, is currently a bottleneck in the development of commercially-available integrated photonic products. In the pursuit of a fully-automated, high-precision, and cost-effective photonic alignment scheme for two multi-channel photonic chips, this paper explores different designs of the on-chip electrothermal actuators for positioning mechanically-flexible waveguide structures. The final alignment goal is ∼100 nm waveguide to waveguide. The on-chip actuators, particularly for out-of-plane actuation, are built in a 16 μm-thick SiO 2 photonic-material stack with 5 μm-thick poly-Si as an electrothermal element. A major challenge of out-of-plane positioning is a 6 μm height difference of the waveguides to be aligned, due to different built-up material stacks, together with a misalignment tolerance of 1 μm–2 μm from the pre-assembly (flip-chip) process. Therefore, the bimorph-actuator design needs to compensate this height difference, and provide sufficient motion to align the waveguides. We propose to exploit the post-release deformation of so-called short-loop bimorph actuator designs to meet these joint demands. We explore different design variants based on the heater location and the integration of actuator beams with waveguide beams. The actuator design (with 30 μm poly-Si and 900 μm SiO 2 in length) has ∼8 μm out-of-plane deflection and is able to generate ∼4 μm motion, which meets the design goal.
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Medina, Rüter, Pujol, Kip, Masons, Ródenas, Aguiló i Díaz. "KLu(WO4)2/SiO2 Tapered Waveguide Platform for Sensing Applications". Micromachines 10, nr 7 (5.07.2019): 454. http://dx.doi.org/10.3390/mi10070454.
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This paper provides a generic way to fabricate a high-index contrast tapered waveguide platform based on dielectric crystal bonded on glass for sensing applications. As a specific example, KLu(WO4)2 crystal on a glass platform is made by means of a three-technique combination. The methodology used is on-chip bonding, taper cutting with an ultra-precise dicing saw machine and inductively coupled plasma-reactive ion etching (ICP-RIE) as a post-processing step. The high quality tapered waveguides obtained show low surface roughness (25 nm at the top of the taper region), exhibiting propagation losses estimated to be about 3 dB/cm at 3.5 m wavelength. A proof-of-concept with crystal-on-glass tapered waveguides was realized and used for chemical sensing.
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MAHDI, SHAIMAA, MORITZ GREHN, AWS AL-SAADI, MICHAEL HÖFNER, STEFAN MEISTER i HANS J. EICHLER. "FACET PREPARATION OF SILICON NANO-WAVEGUIDES BY CLEAVING THE SOI CHIP". Journal of Nonlinear Optical Physics & Materials 20, nr 04 (grudzień 2011): 509–23. http://dx.doi.org/10.1142/s0218863511006315.
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Optical facet preparation of silicon-on-insulator (SOI) waveguides was done by polishing after saw dicing or cleaving after two different techniques of scoring by a mechanical saw and fs-laser. Cleaving after fs-laser scoring leads to smooth facet surface of air covered SOI waveguides; polishing after dicing is more efficient with SiO2covered waveguides. The prepared end facets were investigated using an atomic force microscope (AFM) and scanning electron microscopy (SEM). The SOI waveguides were characterized by optical transmission of telecommunication wavelength (1.5 μm).
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Shalin, Alexander S., Pavel Ginzburg, Pavel A. Belov, Yuri S. Kivshar i Anatoly V. Zayats. "Nano-opto-mechanical effects in plasmonic waveguides". Laser & Photonics Reviews 8, nr 1 (4.11.2013): 131–36. http://dx.doi.org/10.1002/lpor.201300109.
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Amiri, Iraj, Saaidal Azzuhri, Muhammad Jalil, Haryana Hairi, Jalil Ali, Montree Bunruangses i Preecha Yupapin. "Introduction to Photonics: Principles and the Most Recent Applications of Microstructures". Micromachines 9, nr 9 (11.09.2018): 452. http://dx.doi.org/10.3390/mi9090452.
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Light has found applications in data transmission, such as optical fibers and waveguides and in optoelectronics. It consists of a series of electromagnetic waves, with particle behavior. Photonics involves the proper use of light as a tool for the benefit of humans. It is derived from the root word “photon”, which connotes the tiniest entity of light analogous to an electron in electricity. Photonics have a broad range of scientific and technological applications that are practically limitless and include medical diagnostics, organic synthesis, communications, as well as fusion energy. This will enhance the quality of life in many areas such as communications and information technology, advanced manufacturing, defense, health, medicine, and energy. The signal transmission methods used in wireless photonic systems are digital baseband and RoF (Radio-over-Fiber) optical communication. Microwave photonics is considered to be one of the emerging research fields. The mid infrared (mid-IR) spectroscopy offers a principal means for biological structure analysis as well as nonintrusive measurements. There is a lower loss in the propagations involving waveguides. Waveguides have simple structures and are cost-efficient in comparison with optical fibers. These are important components due to their compactness, low profile, and many advantages over conventional metallic waveguides. Among the waveguides, optofluidic waveguides have been found to provide a very powerful foundation for building optofluidic sensors. These can be used to fabricate the biosensors based on fluorescence. In an optical fiber, the evanescent field excitation is employed to sense the environmental refractive index changes. Optical fibers as waveguides can be used as sensors to measure strain, temperature, pressure, displacements, vibrations, and other quantities by modifying a fiber. For some application areas, however, fiber-optic sensors are increasingly recognized as a technology with very interesting possibilities. In this review, we present the most common and recent applications of the optical fiber-based sensors. These kinds of sensors can be fabricated by a modification of the waveguide structures to enhance the evanescent field; therefore, direct interactions of the measurand with electromagnetic waves can be performed. In this research, the most recent applications of photonics components are studied and discussed.
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Zhang, Zhihao, Zhiwei Fang, Junxia Zhou, Youting Liang, Yuan Zhou, Zhe Wang, Jian Liu i in. "On-Chip Integrated Yb3+-Doped Waveguide Amplifiers on Thin Film Lithium Niobate". Micromachines 13, nr 6 (30.05.2022): 865. http://dx.doi.org/10.3390/mi13060865.
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We report the fabrication and optical characterization of Yb3+-doped waveguide amplifiers (YDWA) on the thin film lithium niobate fabricated by photolithography assisted chemo-mechanical etching. The fabricated Yb3+-doped lithium niobate waveguides demonstrates low propagation loss of 0.13 dB/cm at 1030 nm and 0.1 dB/cm at 1060 nm. The internal net gain of 5 dB at 1030 nm and 8 dB at 1060 nm are measured on a 4.0 cm long waveguide pumped by 976 nm laser diodes, indicating the gain per unit length of 1.25 dB/cm at 1030 nm and 2 dB/cm at 1060 nm, respectively. The integrated Yb3+-doped lithium niobate waveguide amplifiers will benefit the development of a powerful gain platform and are expected to contribute to the high-density integration of thin film lithium niobate based photonic chip.
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Schegolev, Andrey E., Nikolay V. Klenov, Anna V. Bogatskaya, Rustam D. Yusupov i Alexander M. Popov. "A Pair of Coupled Waveguides as a Classical Analogue for a Solid-State Qubit". Sensors 22, nr 21 (28.10.2022): 8286. http://dx.doi.org/10.3390/s22218286.
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We have determined conditions when a pair of coupled waveguides, a common element for integrated room-temperature photonics, can act as a qubit based on a system with a double-well potential. Moreover, we have used slow-varying amplitude approximation (SVA) for the “classical” wave equation to study the propagation of electromagnetic beams in a couple of dielectric waveguides both analytically and numerically. As a part of an extension of the optical-mechanical analogy, we have considered examples of “quantum operations” on the electromagnetic wave state in a pair of waveguides. Furthermore, we have provided examples of “quantum-mechanical” calculations of nonlinear transfer functions for the implementation of the considered element in optical neural networks.
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Hildenstein, Philipp, David Feise, Felix Mauerhoff, Nils Werner, Katrin Paschke i Günther Tränkle. "Switchable thermal waveguides in GaAs based devices". AIP Advances 13, nr 2 (1.02.2023): 025358. http://dx.doi.org/10.1063/5.0132023.
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The modulation of light within microscopic devices is the key to designing versatile and powerful photonic integrated circuits (PICs). Contemporary techniques are able to generate a wide range of waveguiding and waveforming elements. They are implemented by the etching of trenches, laser induced waveguide writing, and many other techniques. However, most of the fabricated structures feature a static waveguiding behavior that remains unaltered after processing the devices. In this work, we demonstrate the simulation, design, and experimental behavior of truly switchable microscopic waveguides. We demonstrate the presence of waveguiding and forming elements by localized heating, leading to a tunable refractive index profile in GaAs based devices. We give insights into the microscopic behavior by multi-physics simulations in the mechanical, thermal, and optical domains. This approach opens the way to further possibilities in the design of PICs and useful modifications within existing diode laser and amplifier setups.
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Renno, Jamil, Sadok Sassi i Wael I. Alnahhal. "Calculating the response of waveguides to base excitation using the wave and finite element method". Journal of Vibration and Control, 26.01.2021, 107754632098131. http://dx.doi.org/10.1177/1077546320981315.
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The prediction of the response of waveguides to time-harmonic base excitations has many applications in mechanical, aerospace and civil engineering. The response to base excitations can be obtained analytically for simple waveguides only. For general waveguides, the response to time-harmonic base excitations can be obtained using the finite element method. In this study, we present a wave and finite element approach to calculate the response of waveguides to time-harmonic base excitations. The wave and finite element method is used to model free wave propagation in the waveguide, and these characteristics are then used to find the amplitude of excited waves in the waveguide. Reflection matrices at the boundaries of the waveguide are then used to find the amplitude of the travelling waves in the waveguide and subsequently the response of the waveguide. This includes the displacement and stress frequency response transfer functions. Numerical examples are presented to demonstrate the approach and to discuss the numerical efficiency of the proposed method.
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Ndi, Francis C., i Jean Toulouse. "Photonic Crystal Tapers for Coupling Large Ridge Waveguides to Photonic Crystal Waveguides". MRS Proceedings 797 (2003). http://dx.doi.org/10.1557/proc-797-w5.8.
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ABSTRACTWe present a study of various photonic crystal taper structures each characterized by the taper angle and roughness for coupling light into 2-dimensional photonic crystal waveguides from large ridge waveguides. The photonic crystal waveguide is made of a triangular lattice of holes in a dielectric. The objective is to find a taper structure that offers the best coupling efficiency over a range of widths of the ridge waveguide while leaving a small footprint. We show that such a structure indeed exists and can be further optimized as the width of the ridge waveguide gets even larger leading to more than 90% increase in coupling efficiency in some cases.
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Nashimoto, K., S. Nakamura, H. Moriyama, K. Haga, M. Watanabe, T. Morikawa, E. Osakabe i T. Takeda. "Integrated (Pb,La)(Zr,Ti)O3 Heterostructure Waveguide Devices Fabricated by Solid-Phase Epitaxy". MRS Proceedings 597 (1999). http://dx.doi.org/10.1557/proc-597-151.
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AbstractHeterostructures of a Pb(Zr,Ti)O3 (PZT) waveguide/(Pb,La)(Zr,Ti)O3 (PLZT) system buffer layer were grown on a Nb-doped SrTiO3 (Nb:ST) substrate by solid-phase epitaxy. The propagation loss in the PLZT heterostructure waveguides was on the order of I dB/cm. An electro-optic beam deflection device with an ITO prism electrode on the surface of the PLZT heterostructure waveguide presented efficient deflection of the coupled laser beam by applying a voltage between the electrode and the substrate. A beam deflection greater than 10 mrad at 5 V and frequency response as fast as 13 MHz were observed. An apparent electro-optic coefficient as large as 39 pmJV was estimated from the deflection characteristics for the TE mode and TM mode suggesting the polarization independent nature of the PZT waveguide. For integrating the electrooptic PLZT heterostructure waveguides, channel waveguides were fabricated in the PZT waveguides using a simple wet-etching process. Based on a low-voltage drive structure, lowloss waveguide process, and fine patterning process, a fabricated digital matrix switch showed a – 10 dB cross-talk at a voltage as low as 7.5 V.
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Herreros, B., G. Lifante, F. CussÓ, A. Kling, J. C. Soares, M. F. Da Silva, P. D. Townsend i P. J. Chandler. "Structural and Optical Properties of Rare-Earth Doped Lithium Niobate Waveguides Formed by Mev Helium Implantation". MRS Proceedings 396 (1995). http://dx.doi.org/10.1557/proc-396-355.
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AbstractResults of investigations of optical waveguides formed by high energy helium implantation into lithium niobate codoped with 5 mol% MgO and 1 mol% Tm3+ or 1 mol% Er3+ are reported. A comparative study of structural and luminescence properties between implanted and untreated samples has been performed by means of Rutherford backscattering (RBS) combined with channeling and photoluminescence methods, respectively in order to investigate residual lattice damage and the incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation on the lithium site and a high crystal quality in both bulk and implanted waveguide material has been found. For Er doped lithium niobate the channeling results show a fraction of Er randomly incorporated or forming precipitates and a deterioration of the waveguide's lattice. The optical investigations show in both cases only a slight broadening of the emission lines of the rare earths in the waveguides compared to the bulk material.
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Block, B. A., B. W. Wessels, D. M. Gill, C. W. Conrad i S. T. Ho. "The Optical Properties of Channel Waveguides in Batio3 Thin Films". MRS Proceedings 446 (1996). http://dx.doi.org/10.1557/proc-446-349.
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AbstractBaTiO3 epitaxial films have been prepared on (001) MgO substrates by metalorganic chemical vapor deposition. The as‐deposited 0.2 μm thick films had a surface roughness of 12 nm. Channel waveguides were fabricated from the films and the optical throughput measured. To differentiate the surface scattering loss from the internal scattering loss, waveguides were also prepared with a surface planarization step to reduce the surface roughness to 2.5 nm. The waveguide loss was greatly reduced for the planarized waveguides. The results indicate that surface and side wall roughness accounted for the majority of the waveguide loss. Grain boundary grooving lead to surface roughness and routes to overcome this problem are discussed.
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Lea, E., B. L. Weiss, H. Rho i H. E. Jackson. "Photoelastic Waveguides In Sige/Si Heterostructures And Bulk Si". MRS Proceedings 486 (1997). http://dx.doi.org/10.1557/proc-486-95.
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AbstractPhotoelastic waveguides in bulk Si and SiGe/Si heterostructures have been modelled and characterised. The calculated transverse strain profiles of photoelastic waveguide structures in SiGe/Si heterostructures and bulk silicon are in good agreement with those obtained by microRaman experiments. The waveguide characteristics are also found to be in good agreement with those obtained from the strain modelling and demonstrate that low loss waveguides can be fabricated using these structures
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Lo, Kai-Ming. "Analysis of AlGaAs/GaAs Multiple Quantum Well Dual Waveguides Defined by Ion Implantation Induced Intermixing". MRS Proceedings 484 (1997). http://dx.doi.org/10.1557/proc-484-467.
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AbstractA simple and accurate model is presented for the study of ion-implanted AlGaAs/GaAs multi-quantum well dual waveguides. The impurity induced disordering defined multiquantum well dual waveguides are shown to have similar optical properties as conventional dielectric rib waveguides. They also provide a more flexible control over the waveguiding and coupling characteristics by changing parameters such as diffusion time, ion implant energy, mask width, and waveguide separation.
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Taylor, T., D. Ila, R. L. Zimmerman, P. R. Ashley i D. B. Poker. "Fabrication of Optical Channel Waveguides in the GaAs/AlGaAs System by Mev Ion Beam Bombardment". MRS Proceedings 373 (1994). http://dx.doi.org/10.1557/proc-373-457.
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AbstractWe have fabricated optical channel waveguides in planar GaAs/AlGaAs waveguides using 10 MeV oxygen ions at a fluence of 3x1013 and 3x1014 ions/cm2. Although disordering of GaAs/AlGaAs quantum well structures has previously been reported, to the best of the authors' knowledge the fabrication of channel waveguides using high energy oxygen bombardment has not been demonstrated in this material system. This technique may provide a totally new concept of localized material modifications in GaAs/AlGaAs waveguides by creating compositional disordered regions that act as optical confinement channels. The masking technique used to provide selective disordering of the planar waveguide structures will be presented. Optical measurements were performed on the channel waveguides at a wavelength of 1.3 μm.
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Chen, Kang, Takasuke Irie, Takashi Iijima i Takeshi Morita. "Double-parabolic-reflectors acoustic waveguides for high-power medical ultrasound". Scientific Reports 9, nr 1 (grudzień 2019). http://dx.doi.org/10.1038/s41598-019-54916-2.
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AbstractHigh intensity focused ultrasound therapeutics are widely used to noninvasively treat various types of primary tumors and metastasis. However, ultrasound penetration depth is shallowed with increasing frequency which limits the therapeutic accuracy for deep tissues. Although acoustic waveguides are commonly inserted into tissue for localized therapy, powerful ultrasound delivery is difficult. Here, we invent double-parabolic-reflectors acoustic waveguides, where high-power ultrasound emission and large mechanical vibration enhance the therapeutic efficiency. High-energy-density ultrasound with around 20 times amplification by two parabolic reflectors propagates through the thin waveguide between 1 to 2 MHz, and wideband large mechanical vibration at the waveguide tip from 1 kHz to 2.5 MHz accelerates the therapeutics. This fundamental work serves as a milestone for future biomedical applications, from therapeutics to diagnostics. Since the high-power ability at high frequencies, our waveguide will also open up new research fields in medical, bio, physics and so on.
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Yu, Tai-Ho. "Dispersion Analysis and Material Property Identification of a Circular Piezoelectric Ridge Waveguide". Journal of Computational and Nonlinear Dynamics 16, nr 12 (19.10.2021). http://dx.doi.org/10.1115/1.4052572.
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Abstract This study investigates the dispersive properties of ridge waves that travel circumferentially around piezoelectric circular ridge waveguides and investigates their resonant modes. Based on the variable separation method and Hamilton's principle, the displacement of ridge waveguides is represented as the product of a cross-sectional coordinate-dependent function and the propagator along the circumference of a circular ridge waveguide. The dispersion curves of the flexural waves and resonant frequencies corresponding to ridge waveguides are solved numerically by applying the bidimensional finite element method (Bi-d FEM) and using the three-dimensional (3D) ansys package. The estimated impedance curves are compared with the predicted dispersion curves of waves from ridge waveguides to validate the proposed numerical approach. The elastic constants of the circular piezoelectric ridge waveguide are determined through an inverse scheme that is based on the modified simplex method. The numerical and experimental results show that by using the modified simplex method to inverse calculate the elastic constants and geometric parameters of the piezoelectric circular ridge waveguides, a good degree of accuracy and sensitivity can be achieved.
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Alonso, Jose S., Ricardo A. Burdisso, Douglas Ivers i Hwa W. Kwan. "Adaptive Concepts for Herschel–Quincke Waveguides". Journal of Vibration and Acoustics 135, nr 3 (25.04.2013). http://dx.doi.org/10.1115/1.4023830.
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The enhancement of Herschel–Quincke (HQ) waveguides to incorporate adaptive capabilities is investigated. Passive HQ waveguides are known to provide noise attenuation in pipes and ducts at selective narrow frequency bands associated with their resonances. The approach to achieve adaptation is to produce a frequency shift in these resonances to allow targeting incoming tonal noise of variable frequency. The frequency shift is obtained by placing a variable cross-section constriction along the interior of the waveguide. Two adaptive devices are considered. The first consists of a ball with fixed diameter that can be axially displaced inside the waveguide. Then, the frequency tuning is obtained as a function of the ball position. The second device consists of a diaphragm at fixed axial location which can be deformed to obtain a variable cross section. In this case, the frequency shift is obtained as a function of the diaphragm deflection. The internal acoustic dynamics of the two devices are investigated both analytically and experimentally. The created constriction inside the HQ waveguide is modeled as a series of constant cross-section tube elements with small finite area jump between adjacent pieces. The model is validated by comparing the predicted dynamics with experimental data from an extended impedance tube setup based on the two-microphone technique. Finally, attenuation predictions on a one-dimensional pipe are presented in order to illustrate the performance of the proposed adaptive HQ waveguides.
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de la Peña, I. Molina, R. F. Alvarez-Estrada i M. L. Calvo. "Neutron waveguides with finite repulsive potential in clad". European Physical Journal Plus 137, nr 8 (31.08.2022). http://dx.doi.org/10.1140/epjp/s13360-022-03182-9.
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AbstractThe interaction of an incoming slow neutron with a straight semi-infinite material waveguide (physically, a very lengthy one) located in vacuum (clad) in the infinite three-dimensional (3D) space is studied. The waveguide creates an attractive potential on the neutron. The physical quantum-mechanical wave phenomena are: (i) reflection and scattering of the neutron by the waveguide and (ii) its confined propagation along the latter, in specific propagation modes. The direct application of standard scattering integral equations meets several difficulties, arising mainly from the infinite length of the waveguide and (ii). New and more convenient 3D scattering integral equations are proposed and discussed, using suitable Green functions, adequate for the semi-infinite waveguide and accounting for (i) and the above difficulties. Approximate formulae for the probability amplitudes and fluxes for (i) and (ii) are given: in particular, the formulas for slow neutron confined propagation extend the ones given previously for optical waveguides. Some detailed applications and numerical computations for two-dimensional media and waveguides are presented.
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Nashimoto, Keiichi, Shigetoshi Nakamura, Hiroaki Moriyama, Masao Watanabe i Eisuke Osakabe. "PZT Electro-Optic Waveguide Devices Fabricated by Solid-Phase Epitaxy". MRS Proceedings 493 (1997). http://dx.doi.org/10.1557/proc-493-383.
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ABSTRACTHigh quality epitaxial PZT optical waveguides have been grown by solid-phase epitaxy based on metal alkoxide solution process. Optical propagation loss was 4 dB/cm in epitaxial PZT thin film optical waveguides grown on SrTiO3 substrates. Epitaxial PZT optical waveguides were grown on Nb doped conductive SrTiO3 substrates, since considerable reduction in drive voltage will be expected when top electrode / optical waveguide / conductive substrate structures are realized. Propagation loss was relatively large, as compared with the structure using non-dope insulative substrates. Preliminary electrooptic deflection devices were fabricated by preparing prism electrodes on the surface of the PZT optical waveguides. Efficient deflection/switching of coupled laser beam in the PZT optical waveguides as large as 26 mrad was observed by applying 70 volts between prism electrode and Nb doped SrTiO3 substrates.
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Reed, Graham T., Goran Z. Mashanovich, Branislav D. Timotijevic, Frederic Y. Gardes, William R. Headley i Nicholas Wright. "Silicon Photonic Devices and Polarisation Independence". MRS Proceedings 958 (2006). http://dx.doi.org/10.1557/proc-0958-l02-01.
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ABSTRACTSilicon Photonics is experiencing a dramatic increase in interest due to emerging application areas and several high profile successes in device and technology development. For both performance and cost reasons, there is a worldwide trend towards miniaturising silicon photonic waveguides. The shrinking of the device dimensions provides advantages in terms of cost and packing density, modulation bandwidth, improved performance in resonant structures, and an increase in optical power density within the devices. However, the size reduction comes at some costs in increased difficulty in maintaining single mode operation of the waveguides whilst controlling the polarisation properties of the device.For some applications, it is essential that optical modulators and filters, as well as other components, operate in the single mode regime. It is also desirable that these components are polarisation insensitive. Design of the waveguide, which is the basic element of these devices, is therefore crucial. Due to the compatibility with single mode fibre dimensions as well as the possibility of control of polarisation, rib waveguides represent promising candidates for integration in SOI. The main limitation for rib waveguides is that the bend radius cannot always be sufficiently small to minimise the device footprint. Strip waveguides, on the other hand, are often considered as a good choice in this respect, as they allow very small bend radii resulting in a compact footprint. However, polarisation dependence of these waveguides can be significant. Therefore, both waveguide configurations are investigated in this paper, together with the implications for optical modulators.Following from this discussion, we also consider optical modulators that operate in the depletion mode with the intrinsic bandwidth of several tens of gigahertz. We have previously reported a modulator based on a small rib waveguide with the height of < 500nm for high speed operation. However, in this paper we consider slightly larger designs to accommodate polarisation independence. Finally we discuss the characteristics of ring and racetrack resonators based on both rib and strip waveguides and methods of improving free spectral range whilst considering polarization effects. Both theoretical and experimental results are presented. The maximum free spectral range that we have demonstrated experimentally is ∼43nm.
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Sasaki, K., S. Sasaki i O. Furukawa. "All-Optical Switches and All-Optical Bistability by Nonlinear Optical Materials". MRS Proceedings 247 (1992). http://dx.doi.org/10.1557/proc-247-141.
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ABSTRACTAll-optical switches and all-optical bistabili ties are realized by waveguide structures with vacuum evaporated polydiacetylene(PDA) films. The basic structure of the all-optical switches are prepared in the form of layered waveguide directional coupler with vacuum evaporated PDA top layer. Clearly switchings are observed at 1064nm of pulsed Nd:YAG laser. Furthermore ultra-high speed switching with Ti;Safire 135fs laser are recognized.Operations of all-optical bistabilities are carried out by nonlinear coupling at grating structures in waveguides with PDA top layers. Hysterisis curves of bistability are affected by coupling parameters of gratings and parameters of waveguides.
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Bestwick, Tim D. "Active Silicon Integrated Optical Circuits". MRS Proceedings 486 (1997). http://dx.doi.org/10.1557/proc-486-57.
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AbstractActive Silicon integrated Optical Circuits (ASOC™) is a technology based on single-mode rib waveguides formed on silicon-on-insulator that is being used to manufacture commercial integrated optics components. Silicon waveguides have excellent properties for many applications in the 1.3 and 1.55 micron telecommunications bands including relatively low loss. An important aspect of ASOC™ technology is the development of a set of waveguide-based elements that can be assembled into practical integrated optics devices. The fundamental waveguide elements include bends, couplers and fiber-waveguide interfaces, and additional elements include doped structures and waveguide gratings. Discrete lasers and photodetectors are also incorporated into ASOC™ technology to form hybrid devices. The technology is being used to manufacture devices for applications in telecomunications and optical sensing, the first major product being a two-wavelength single-fiber bi-directional optical transceiver.