Articoli di riviste: "Electro-optical sampling"

1

Li, Yuelin. "Electro-optical sampling at near-zero optical bias". Applied Physics Letters 88, n. 25 (19 giugno 2006): 251108. http://dx.doi.org/10.1063/1.2214143.

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Shiktorov, P., E. Starikov, V. Gružinskis, L. Varani e L. Reggiani. "Modeling of THz - Electro-Optical Sampling Measurements". Acta Physica Polonica A 113, n. 3 (marzo 2008): 913–16. http://dx.doi.org/10.12693/aphyspola.113.913.

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3

Nikles, Marc. "Optical sampling using wideband electro-optic modulators". Optical Engineering 34, n. 7 (1 luglio 1995): 2078. http://dx.doi.org/10.1117/12.204801.

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4

Shields, Taylor, Adetunmise C. Dada, Lennart Hirsch, Seungjin Yoon, Jonathan M. R. Weaver, Daniele Faccio, Lucia Caspani, Marco Peccianti e Matteo Clerici. "Electro-Optical Sampling of Single-Cycle THz Fields with Single-Photon Detectors". Sensors 22, n. 23 (2 dicembre 2022): 9432. http://dx.doi.org/10.3390/s22239432.

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Electro-optical sampling of Terahertz fields with ultrashort pulsed probes is a well-established approach for directly measuring the electric field of THz radiation. This technique usually relies on balanced detection to record the optical phase shift brought by THz-induced birefringence. The sensitivity of electro-optical sampling is, therefore, limited by the shot noise of the probe pulse, and improvements could be achieved using quantum metrology approaches using, e.g., NOON states for Heisenberg-limited phase estimation. We report on our experiments on THz electro-optical sampling using single-photon detectors and a weak squeezed vacuum field as the optical probe. Our approach achieves field sensitivity limited by the probe state statistical properties using phase-locked single-photon detectors and paves the way for further studies targeting quantum-enhanced THz sensing.

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Fuji, Takao, Yutaka Nomura, Hideto Shirai e Noriaki Tsurumachi. "Frequency-resolved optical gating with electro-optic sampling". EPJ Web of Conferences 41 (2013): 12001. http://dx.doi.org/10.1051/epjconf/20134112001.

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Jiang, Zhiping, F. G. Sun, Q. Chen e X. C. Zhang. "Electro-optic sampling near zero optical transmission point". Applied Physics Letters 74, n. 9 (marzo 1999): 1191–93. http://dx.doi.org/10.1063/1.123495.

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7

Krotkus, A., D. Hoffmann, R. Ludwig e S. Diez. "Optical sampling technique for fast electro-optic devices". Electronics Letters 34, n. 19 (1998): 1877. http://dx.doi.org/10.1049/el:19981286.

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8

Jong, Kuo-Chin, Hen-Wai Tsao e San-Liang Lee. "Novel optical performance monitoring techniques using jittered electro-optical sampling pulses". Microwave and Optical Technology Letters 50, n. 7 (2008): 1831–34. http://dx.doi.org/10.1002/mop.23504.

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Li, Jian Wei, Nan Xu, Jian Li e Zhi Xin Zhang. "Ultrafast Electrical Signal Electro-Optic Sampling Test Theory and Test System". Advanced Materials Research 571 (settembre 2012): 471–75. http://dx.doi.org/10.4028/www.scientific.net/amr.571.471.

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Discussed the principle of electro-optic sampling technique and implementation methods of Ultra-fast electrical signals, the electric field of electro-optical crystal and sampling pulses as well as the interaction between the principle of time scanning unit, established the coplanar waveguide parameters model, and analyzed the technical indicators of test system.

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Zhukova, M. O., E. A. Makarov, S. E. Putilin, A. N. Tsypkin, V. P. Chegnov, O. I. Chegnova e V. G. Bespalov. "Two-photon absorption in THz electro-optical sampling crystals". Journal of Physics: Conference Series 1062 (luglio 2018): 012009. http://dx.doi.org/10.1088/1742-6596/1062/1/012009.

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11

Ma, Bo-Wen, Wen Dai, Fei Meng, Jia-Ning Tao, Zi-Ling Wu, Yan-Qing Shi, Zhan-Jun Fang, Ming-Lie Hu e You-Jian Song. "Using asynchronous optical sampling to measure timing jitter of electro-optic frequency combs". Acta Physica Sinica 73, n. 14 (2024): 144203. http://dx.doi.org/10.7498/aps.73.20240400.

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<sec>Electro-optic frequency combs (EOCs) are optical frequency combs constructed by phase modulation of single frequency lasers. The electro-optic modulated optical frequency combs have shown their unique advantages in many application fields due to their high repetition frequencies, high stabilities and other advantages, especially in precision measurement applications. Through accurate dispersion control, the electro-optical frequency combs can output ultra-short pulse laser sequences in the time domain, and their timing jitter characteristic is very important for precision measurement and other applications. This work presents a scheme to measure the timing jitter of the electro-optic combs directly in the time domain based on the principle of dual-comb asynchronous optical sampling method(ASOPS), which relies on temporal cross-correlation between the high repetition rate electro-optic combs and a low repetition rate passively mode-locked fiber laser. The ASOPS process allows timing jitter measurement in a magnified time scale where the timing jitter at a femtosecond level can be received and visualized by standard low speed electronics. We build a theoretical model for timing jitter measurement, conduct a numerical study to verify the model, and also construct an experimental system to characterize the period jitter of a 10-GHz electro-optic comb.</sec><sec>Firstly, the theoretical model for measuring timing jitter is established. In this work, the basic theory of measuring the timing jitter is discussed by analyzing the histogram directly in time domain through using the obtained ASOPS signal. Subsequently, numerical simulations are conducted to simulate the ASOPS process after establishing a sequence of Gaussian pulse train with quantum limited timing jitter. Another pulse train without timing jitter serves as a local oscillator. Through the square law optical detection after sum-frequency generation between LO and LUT, the ASOPS process can be realized and periodic jitter can be obtained directly through histogram statistical analysis. The simulation result is consistent with the theoretical result very well. Finally, an EOC system with cascaded modulators at a repetition rate of 10 GHz is designed and built, and a timing jitter measurement system is designed and built with an all-fiber configuration. The period jitter of 10-GHz EOC is measured by using a 161-MHz mode-locked fiber laser as local oscillator. Histogram analysis shows that the period jitter of the EOC is 3.86 fs.</sec><sec>This measurement technique does not require to use the intricate electrical phase-locked circuits or a high-speed photodetector to receive ultrashort pulses of EOC. Like the eye map analysis method commonly used in telecommunication, the histogram analysis can be used to determine the timing jitter approaching the quantum limit. This approach is easy to set up and operate, and it is anticipated to become a standard method of measuring period jitter of ultrashort pulse with high repetition frequency in a laboratory setting. It will be particularly useful for measuring timing jitters of the sources of novel high repetition rate optical frequency combs, such as micro-resonators and electro-optic frequency combs.</sec>

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12

Song, Jian, David Conn, Xiaohua Wu e Kent Nickerson. "An equivalent circuit model of the optical probe in electro-optical sampling systems". Microwave and Optical Technology Letters 6, n. 8 (20 giugno 1993): 493–98. http://dx.doi.org/10.1002/mop.4650060812.

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13

Kai-Xin, Chen, Yang Han, Zhang Da-Ming, Zhang Hong-Bo e Yi Mao-Bin. "External Electro-optic Sampling Utilizing an Asymmetric Fabry-Pérot Film of Poled Electro-optical Polymer". Chinese Physics Letters 18, n. 6 (3 maggio 2001): 782–84. http://dx.doi.org/10.1088/0256-307x/18/6/323.

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14

Kleopin, Andrey V., e Ivan M. Malay. "Modern approaches to ensure traceability of fast electrical pulse processes measurements". Izmeritel`naya Tekhnika, n. 9 (2021): 47–53. http://dx.doi.org/10.32446/0368-1025it.2021-9-47-53.

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The necessity of improving the State primary special standard for a unit of pulsed electric voltage GET 182-2010 is substantiated on the basis of an electro-optical sampling system. Approaches to ensure the uniformity of pulse measurements are proposed, aimed at developing a new system of measurements traceability of pulsed signals parameters to the units of the International System of Units, as well as ensuring independent reproduction of reference ultra-wideband electrical pulses. The considered approaches can be used to work on GET 182-2010 improvement. The main tasks of further research in the direction of creating a domestic electro-optical sampling system are formulated.

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15

Endo, M., T. Inoue e T. Honda. "Picosecond optical pulse measurement based on an electro-optic sampling technique". IEEE Transactions on Instrumentation and Measurement 38, n. 2 (aprile 1989): 565–68. http://dx.doi.org/10.1109/19.192348.

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16

Termos, Hassan, e Ali Mansour. "Frequency Alteration Built on an Electro-Optical Sampling SOA–MZI Using a Differential Modulation Schema". Optics 3, n. 3 (11 luglio 2022): 225–33. http://dx.doi.org/10.3390/opt3030022.

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In this paper, we present a real and simulated study of a frequency up mixing employing an electro-optical sampling semiconductor optical amplifier Mach–Zehnder interferometer (SOA–MZI) along with the differential modulation schema. The sampling signal is generated by an optical pulse clock (OPC) at a frequency of fs= 19.5 GHz. The quadratic phase shift keying (QPSK) signal at an intermediate frequency (IF) fIF is shifted to high frequencies nfs ± fIF at the SOA–MZI output. Using a simulator entitled Virtual Photonics Inc. (VPI), we generate sampled QPSK signals and analyze their merits during conversion gains and error vector magnitudes (EVMs). We conducted simulations of mixing in the SOA–MZI operating in a high-frequency band up to 195.5 GHz. The positive conversion gain is accomplished over the mixing frequencies. The EVM is used to evaluate the performance of the electro-optical sampling up-convertor. The EVM reaches 14% at a data rate of 5 Gbit/s at 195.5 GHz. During the experimental work, the results obtained in simulations are set side by side with the factual ones in the frequency range up to 59 GHz. Thus, the comparison between them confirms that they have approximately the same performance.

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17

Xu, Bingxin, Xinyu Fan, Shuai Wang e Zuyuan He. "Generalized Linear Optical Sampling Technique Realized by Using Non-Pulse Electro-Optic Frequency Comb Sampling Source". IEEE Access 8 (2020): 114259–65. http://dx.doi.org/10.1109/access.2020.3003780.

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Zhukova, M., E. Makarov, S. Putilin, A. Tsypkin, V. Chegnov, O. Chegnova e V. Bespalov. "Experimental study of THz electro-optical sampling crystals ZnSe, ZnTe and GaP". Journal of Physics: Conference Series 917 (novembre 2017): 062021. http://dx.doi.org/10.1088/1742-6596/917/6/062021.

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19

Chen, Kaixin, Hongbo Zhang, Daming Zhang, Han Yang e Maobin Yi. "External electro-optic sampling utilizing a poled polymer asymmetric Fabry–Perot cavity as an electro-optical probe tip". Optics & Laser Technology 34, n. 6 (settembre 2002): 449–52. http://dx.doi.org/10.1016/s0030-3992(02)00037-3.

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20

Nahata, Ajay, Aniruddha S. Weling e Tony F. Heinz. "A wideband coherent terahertz spectroscopy system using optical rectification and electro‐optic sampling". Applied Physics Letters 69, n. 16 (14 ottobre 1996): 2321–23. http://dx.doi.org/10.1063/1.117511.

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21

Torres, J., L. Varani, F. Teppe, W. Knap, S. Boubanga-Tombet, T. Otsuji, P. Shiktorov, E. Starikov e V. Gružinskis. "Investigation of 2D plasma resonances in HEMTs by using electro-optical sampling technique". Lithuanian Journal of Physics 51, n. 4 (2011): 324–29. http://dx.doi.org/10.3952/lithjphys.51405.

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22

Yang, Fan, Wei Yan, Peng Tian, Fanxin Li e Fupin Peng. "Electro-Optical Imaging Technology Based on Microlens Array and Fiber Interferometer". Applied Sciences 9, n. 7 (29 marzo 2019): 1331. http://dx.doi.org/10.3390/app9071331.

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To reduce the volume and weight of traditional optical telescopes effectively, this article proposes an electro-optical imaging technology based on a microlens array and fiber interferometer. Pairs of microlenses in the microlens array collect light and couple it into a fiber interferometer to form interference fringes. Then the amplitude and phase of a large number of interferometer baselines are analyzed to generate images. In this work, the principle of electro-optical imaging technology has been analyzed according to the partially coherent light theory. The microlens-array arrangement method and baseline pairing method have been optimized for arbitrary targets. From the simulation results, it was found that the imaging resolution depends on the maximum baseline length, and the imaging quality could be effectively improved by adjusting the Nyquist sampling density and baseline pairing method. This technology can provide an important reference for the miniaturization and complanation of imaging systems.

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23

Yuan, Xingming, Ying Li, Qinggang Lin, Jiapin Chen, Yi Cai, Shixiang Xu e Jingzhen Li. "Broadband THz Edge-Enhanced Imaging Technology Based on Electro-Optic Sampling". Journal of Physics: Conference Series 2525, n. 1 (1 giugno 2023): 012025. http://dx.doi.org/10.1088/1742-6596/2525/1/012025.

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Abstract Based on the radial Hilbert transform of spatial filtering and electro-optical sampling, we propose a broadband terahertz edge-enhanced imaging method in this work. Instead of using a narrow-band THz vortex phase plate, here we use vortex ultrashort laser pulse to realize the THz enhancement imaging which can be applied for few-cycle THz imaging. The principle of edge enhancement is analyzed theoretically, and the analytical expression of the final terahertz imaging is derived. We found that edge-enhancement imaging corresponds to the nonlinear term of the THz field, and the background and linear terms can be suppressed when the static birefringent phase is set to zero. The simulations show that our method can effectively improve the contrast and signal-to-noise ratio of terahertz imaging.

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24

Faure, J., J. Van Tilborg, R. A. Kaindl e W. P. Leemans. "Modelling Laser-Based Table-Top THz Sources: Optical Rectification, Propagation and Electro-Optic Sampling". Optical and Quantum Electronics 36, n. 8 (giugno 2004): 681–97. http://dx.doi.org/10.1023/b:oqel.0000039617.85129.c2.

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25

Shibata, T., T. Nagatsuma e E. Sano. "Effective optical transit time in direct electro-optic sampling of GaAs coplanar integrated circuits". Electronics Letters 25, n. 12 (1989): 771. http://dx.doi.org/10.1049/el:19890521.

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26

Shirai, Hideto, Keiji Uzumi, Shyun Koshiba, Shunsuke Nakanishi, Hiroshi Itoh e Noriaki Tsurumachi. "Enhancement of terahertz detection efficiency in electro-optical sampling using Fabry-Perot microcavity structure". physica status solidi (c) 8, n. 2 (3 gennaio 2011): 356–58. http://dx.doi.org/10.1002/pssc.201000580.

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27

Adhlakha, Nidhi, Paola Di Pietro, Federica Piccirilli, Paolo Cinquegrana, Simone Di Mitri, Paolo Sigalotti, Simone Spampinati, Marco Veronese, Stefano Lupi e Andrea Perucchi. "The TeraFERMI Electro-Optic Sampling Set-Up for Fluence-Dependent Spectroscopic Measurements". Condensed Matter 5, n. 1 (20 gennaio 2020): 8. http://dx.doi.org/10.3390/condmat5010008.

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TeraFERMI is the THz beamline at the FERMI free-electron-laser facility in Trieste (Italy). It uses superradiant Coherent Transition Radiation emission to produce THz pulses of 10 to 100 μ J intensity over a spectral range which can extend up to 12 THz. TeraFERMI can be used to perform non-linear, fluence-dependent THz spectroscopy and THz-pump/IR-probe measurements. We describe in this paper the optical set-up based on electro-optic-sampling, which is presently in use in our facility and discuss the properties of a representative THz electric field profile measured from our source. The measured electric field profile can be understood as the superimposed emission from two electron bunches of different length, as predicted by electron beam dynamics simulations.

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SHAN, JIE, AJAY NAHATA e TONY F. HEINZ. "TERAHERTZ TIME-DOMAIN SPECTROSCOPY BASED ON NONLINEAR OPTICS". Journal of Nonlinear Optical Physics & Materials 11, n. 01 (marzo 2002): 31–48. http://dx.doi.org/10.1142/s0218863502000845.

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We present a brief review of the use of nonlinear optics for broadband terahertz (THz) time-domain spectroscopy with femtosecond laser pulses. The generation of THz pulses is accomplished by optical rectification and coherent detection by electro-optic sampling or field-induced second-harmonic generation. The approach permits exceptional time response, as well as the possibility for multichannel detection schemes.

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Da-Rui, Sun, Xu Jin-Qiang e Chen Sen-Yu. "Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL". Chinese Physics C 34, n. 2 (20 gennaio 2010): 227–30. http://dx.doi.org/10.1088/1674-1137/34/2/014.

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30

Loh, Lup M. "Subnanosecond sampling all‐optical analog‐to‐digital converter using symmetric self‐electro‐optic effect devices". Optical Engineering 35, n. 2 (1 febbraio 1996): 457. http://dx.doi.org/10.1117/1.600915.

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31

Ralph, Stephen E., Federico Capasso e Roger J. Malik. "Transient nonlinear optical properties of δ‐doped asymmetric superlattices measured by picosecond electro‐optic sampling". Applied Physics Letters 57, n. 6 (6 agosto 1990): 626–28. http://dx.doi.org/10.1063/1.103617.

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32

Erschens, Dines Nøddegaard, Dmitry Turchinovich e Peter Uhd Jepsen. "Optimized Optical Rectification and Electro-optic Sampling in ZnTe Crystals with Chirped Femtosecond Laser Pulses". Journal of Infrared, Millimeter, and Terahertz Waves 32, n. 12 (22 settembre 2011): 1371–81. http://dx.doi.org/10.1007/s10762-011-9829-y.

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33

Gaal, P., M. B. Raschke, K. Reimann e M. Woerner. "Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling". Nature Photonics 1, n. 10 (ottobre 2007): 577–80. http://dx.doi.org/10.1038/nphoton.2007.170.

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34

Wu, Bang, Zhe Zhang, Lei Cao, Qiang Fu e Yongqian Xiong. "Electro-optic sampling of optical pulses and electron bunches for a compact THz-FEL source". Infrared Physics & Technology 92 (agosto 2018): 287–94. http://dx.doi.org/10.1016/j.infrared.2018.06.014.

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35

Pradarutti, B., G. Matthäus, S. Riehemann, G. Notni, J. Limpert, S. Nolte e A. Tünnermann. "Electro-optical sampling of ultrashort THz pulses by fs-laser pulses at 530 nm with BaTiO3". Journal of Applied Physics 102, n. 9 (novembre 2007): 093105. http://dx.doi.org/10.1063/1.2809270.

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36

Shi-Xiang, Xu, e Cai Hua. "A Theoretical and Experimental Research on Terahertz Electro-Optic Sampling at Near-Zero Optical Transmission Point". Chinese Physics Letters 25, n. 1 (gennaio 2008): 152–55. http://dx.doi.org/10.1088/0256-307x/25/1/042.

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37

Andronov, V. G., Yu N. Volobuev e А. А. Chuev. "Blurring correction in the electro-optical scanning systems on board a spacecraft". Geodesy and Cartography 959, n. 5 (20 giugno 2020): 26–34. http://dx.doi.org/10.22389/0016-7126-2020-959-5-26-34.

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The authors analyze the existing ways of blurring elimination. It determines the technique and problem solving procedure of blurring correction in electro-optical scanning systems on board a spacecraft. The proposed technique is implemented at the initial stages of the survey and is based on the optimization of CCD matrix sampling rate according to the maximum of parameters dispersion of brightness image fields. In contrast to the known approaches, brightness differences of adjacent lines of survey route are values to be measured. The results of testing the technique on conditional frames of lines with different degrees of blurring obtained by distorting the signals of a real space image are presented. The authors’ new approach based on the established functional relationship between the level of blurring, survey parameters and errors of their determination was applied for the blurring simulation. The obtained results prove the possibility of reducing the initial blurring of images being formed on board a spacecraft to the magnitude of tenths of a pixel.

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Pan, Xinjian, Yi Cai, Xuanke Zeng, Xiaowei Lu, Dongping Zhang, Jingzhen Li, Hongyi Chen e Shixiang Xu. "Modified THz electro-optic sampling for high optical modulation depth, large dynamical range, and low background noises". Optics Letters 39, n. 13 (19 giugno 2014): 3778. http://dx.doi.org/10.1364/ol.39.003778.

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Shur, M., S. Rudin, G. Rupper, M. Yamaguchi, X. Shen e A. Muraviev. "Subpicosecond Nonlinear Plasmonic Response Probed by Femtosecond Optical Pulses". International Journal of High Speed Electronics and Systems 25, n. 01n02 (marzo 2016): 1640003. http://dx.doi.org/10.1142/s0129156416400036.

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The hydrodynamic model of the electron transport in the channel of a nanoscale field effect transistors predicts that three different electron transport regimes – collision-dominated, ballistic, and viscosity dominated – determine the ultimate response time of the semiconductor device depending on its length, momentum relaxation time, and viscosity. The characteristic response times of ultra-short channel transistors are in the subpicosecond range. We now report on a new measurement technique with a greatly enhanced sensitivity using optical band-to-band pulses with a controlled delay. The measurements using this new electro-optic sampling and hydrodynamic modeling reveal the ultra-fast transistor plasmonic response at the time scale much shorter than the electron transit time.

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Roberts, Lyle E., Robert L. Ward, Craig Smith e Daniel A. Shaddock. "Coherent Beam Combining Using an Internally Sensed Optical Phased Array of Frequency-Offset Phase Locked Lasers". Photonics 7, n. 4 (28 novembre 2020): 118. http://dx.doi.org/10.3390/photonics7040118.

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Coherent beam combining can be used to scale optical power and enable mechanism-free beam steering using an optical phased array. Coherently combining multiple free-running lasers in a leader-follower laser configuration is challenging due to the need to measure and stabilize large and highly dynamic phase differences between them. We present a scalable technique based on frequency-offset phase locking and digitally enhanced interferometry to clone the coherence of multiple lasers without the use of external sampling optics, which has the potential to support both coherent and spectral beam combining, and alleviates issues of voltage wrapping associated with actuating feedback control using electro-optic modulators. This technique was demonstrated experimentally using a tiled-aperture optical phased array in which the relative output phase of three free-running lasers was stabilized with an RMS output phase stability of λ/104.

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Liu, Wei, Zhaowen Yan, Jianwei Wang, Zhaoming Ning e Zheng Min. "Ultrawideband Real-Time Monitoring System Based on Electro-Optical Under-Sampling and Data Acquisition for Near-Field Measurement". IEEE Transactions on Instrumentation and Measurement 69, n. 9 (settembre 2020): 6603–12. http://dx.doi.org/10.1109/tim.2020.2968755.

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Ju, Hai Lang, Xiong Li, Bao He Li e Bi Hun Hou. "Absorption Peaks Study of β-Zn₃BPO₇ Crystal in THz Band". Materials Science Forum 687 (giugno 2011): 12–14. http://dx.doi.org/10.4028/www.scientific.net/msf.687.12.

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Using electro-optic sampling technique and THz time-domain spectroscopy-transmission equipment, the reference THz wave and the sample THz wave has been measured from 0.3 THz to 3.0 THz and the absorption index has been obtained. Absorption peaks of β-Zn3BPO7crystal sample were found in four points. The important condition of direct interaction between lattice and light is that they must have the same frequency and wave vector, also lattice vibration mode should be transverse because the light is electromagnetic wave. The absorption peaks are found multiple of the optical phonon basically after calculation. The sample shows great resonance absorption.

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43

Ding, Yingying, Liwei Song, Junyu Qian, Zhe Liu, Pengfei Wang, Yanyan Li, Yujie Peng, Ye Tian e Yuxin Leng. "A compact platform for efficient generation and single-shot measurement of high-field terahertz wave with a broadband naturally synchronized mid-infrared source". European Physical Journal Applied Physics 93, n. 1 (gennaio 2021): 10501. http://dx.doi.org/10.1051/epjap/2020200177.

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High-field terahertz (THz) wave is a powerful tool for investigating ultrafast dynamics such as the motion of electrons, the vibration of crystal lattices, the precession of spin, etc. In this letter, we demonstrate the generation of intense single-cycle THz pulses from an organic crystal DSTMS (4-N, N-dimethylamino-4'-N'-methyl–stilbazolium 2,4,6–trimethylbenzenesulfonate) via optical rectification. The generated THz field is characterized by single-shot electro-optic sampling with a linearly chirped probe beam. Meanwhile, the spectrum of the infrared pump is broadened to an octave which supports a 1.9-cycle pulse duration. The proposed scheme displays a sophisticated platform of efficient high-field THz generation, single-shot THz measurement, and a broadband mid-infrared source which is naturally synchronized with the THz pulses.

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Termos, Hassan, e Ali Nansour. "Real & Simulated QPSK Up-Converted Signals by a Sampling Method Using a Cascaded MZMs Link". Photonics 9, n. 1 (7 gennaio 2022): 34. http://dx.doi.org/10.3390/photonics9010034.

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This study focuses on a novel concept of transmitting of a quadrature phase shift keying (QPSK) modulation by an electro-optical frequency up-conversion using a cascaded Mach–Zehnder modulators (MZMs) link. Furthermore, we conduct and compare the results obtained by simulations using the Virtual Photonics Inc. (VPI) (Berlin, Germany) simulator and real-world experiments. The design and operating regime peculiarities of the MZM used as a sampling up-converter mixer in a radio over fiber (RoF) system are also analyzed. Besides, the simulation and experimental results of static and dynamic characteristics of the MZM have approximately the same behavior. The conversion gain of the cascaded MZMs link is simulated over many mixing frequencies and it can decrease from 17.5 dB at 8.3 GHz to −4.5 dB at 39.5 GHz. However, in real world settings, it may decrease from 15.5 dB at 8.3 GHz to −6 dB at 39.5 GHz. The maximum frequency range is attained at 78.5 GHz for up-conversion through simulations. Error vector magnitude (EVM) values have been done to evaluate the performance of our system. An EVM of 16% at a mixing frequency of 39.5 GHz with a bit rate of 12.5 Gbit/s was observed with the considering sampling technique, while it reached 19% in real-world settings with a sampling frequency of 39.5 GHz and a bit rate of 12.5 Gbit/s.

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45

Sasagawa, Kiyotaka, Ryoma Okada, Yoshihiro Akamatsu, Maya Mizuno, Hironari Takehara, Makito Haruta, Hiroyuki Tashiro e Jun Ohta. "Exposure Time Control Method for Higher Intermediate Frequency in Optical Heterodyne Imaging and Its Application to Electric-Field Imaging Based on Electro-Optic Effect". Sensors 24, n. 4 (15 febbraio 2024): 1249. http://dx.doi.org/10.3390/s24041249.

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We propose and demonstrate a method for equivalent time sampling using image sensors to selectively detect only the target frequency. Shortening the exposure time of the image sensor and using equivalent time sampling allows for the detection of frequency components that are higher than the frame rate. However, the imaging system in our previous work was also sensitive to the frequency component at 1/4 of the frame rate. In this study, we control the phase relationship between the exposure time and observed signal by inserting an additional interval once every four frames to detect the target frequency selectively. With this technique, we conducted electric field imaging based on the electro-optic effect under high noise conditions in the low-frequency band to which the conventional method is sensitive. The results demonstrated that the proposed method improved the signal-to-noise ratio.

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46

Zhang, Jiyan, Teng Qin, Zhexin Xie, Liting Sun, Zhengyu Lin, Tianhao Cao e Chentao Zhang. "Design of Airborne Large Aperture Infrared Optical System Based on Monocentric Lens". Sensors 22, n. 24 (16 dicembre 2022): 9907. http://dx.doi.org/10.3390/s22249907.

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Conventional reconnaissance camera systems have been flown on manned aircraft, where the weight, size, and power requirements are not stringent. However, today, these parameters are important for unmanned aerial vehicles (UAVs). This article provides a solution to the design of airborne large aperture infrared optical systems, based on a monocentric lens that can meet the strict criteria of aerial reconnaissance UAVs for a wide field of view (FOV) and lightness of airborne electro-optical pod cameras. A monocentric lens has a curved image plane, consisting of an array of microsensors, which can provide an image with 368 megapixels over a 100° FOV. We obtained the initial structure of a five-glass (5GS) asymmetric monocentric lens with an air gap, using ray-tracing and global optimization algorithms. According to the design results, the ground sampling distance (GSD) of the system is 0.33 m at 3000 m altitude. The full-field modulation transfer function (MTF) value of the system is more than 0.4 at a Nyquist frequency of 70 lp/mm. We present a primary thermal control method, and the image quality was steady throughout the operating temperature range. This compactness and simple structure fulfill the needs of uncrewed airborne lenses. This work may facilitate the practical application of monocentric lens in UAVs.

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47

HAN, P. Y., G. C. CHO e X. C. ZHANG. "BROAD BAND MID-INFRARED THz PULSE: MEASUREMENT TECHNIQUE AND APPLICATIONS". Journal of Nonlinear Optical Physics & Materials 08, n. 01 (marzo 1999): 89–105. http://dx.doi.org/10.1142/s0218863599000072.

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We present in this article the recent development of the measurement technique for coherent free-space THz field and applications in the mid-infrared range. The technique is based on the second-order nonlinear optical interaction both for the generation and for the detection of THz pulse. Particularly the detection process based on free-space electro-optic sampling gives us a possibility to timely trace directly the ultrabroad band coherent THz field unparalleled by other technique. Using an ultrashort laser pulse our measurement system is feasible to measure the ultrashort THz pulse with a bandwidth up to 40 THz. We present a detailed comparative study on the generation and detection using different nonlinear material. We demonstrate applications of the coherent THz technique for time-resolved semiconductor spectroscopy, time-domain imaging with high spatial resolution and broad band refractive and absorptive characterization of material in the mid-infrared range.

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48

Li, Hui, Xulei Qin e Ye Li. "Comparison of terahertz time-domain spectroscopy based on photoconductive antenna and electro-optic sampling and the optical parameter measurement of GaSe nanofilm in THz band". Optik 242 (settembre 2021): 166822. http://dx.doi.org/10.1016/j.ijleo.2021.166822.

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49

Pan, Rui, Ekaterina Zapolnova, Torsten Golz, Aleksandar J. Krmpot, Mihailo D. Rabasovic, Jovana Petrovic, Vivek Asgekar et al. "Photon diagnostics at the FLASH THz beamline". Journal of Synchrotron Radiation 26, n. 3 (26 aprile 2019): 700–707. http://dx.doi.org/10.1107/s1600577519003412.

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Abstract (sommario):

The THz beamline at FLASH, DESY, provides both tunable (1–300 THz) narrow-bandwidth (∼10%) and broad-bandwidth intense (up to 150 uJ) THz pulses delivered in 1 MHz bursts and naturally synchronized with free-electron laser X-ray pulses. Combination of these pulses, along with the auxiliary NIR and VIS ultrashort lasers, supports a plethora of dynamic investigations in physics, material science and biology. The unique features of the FLASH THz pulses and the accelerator source, however, bring along a set of challenges in the diagnostics of their key parameters: pulse energy, spectral, temporal and spatial profiles. Here, these challenges are discussed and the pulse diagnostic tools developed at FLASH are presented. In particular, a radiometric power measurement is presented that enables the derivation of the average pulse energy within a pulse burst across the spectral range, jitter-corrected electro-optical sampling for the full spectro-temporal pulse characterization, spatial beam profiling along the beam transport line and at the sample, and a lamellar grating based Fourier transform infrared spectrometer for the on-line assessment of the average THz pulse spectra. Corresponding measurement results provide a comprehensive insight into the THz beamline capabilities.

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50

Laghezza, Francesco, Fabrizio Berizzi, Amerigo Capria, Andrea Cacciamano, Giovanni Serafino, Paolo Ghelfi e Antonella Bogoni. "Reconfigurable radar transmitter based on photonic microwave signal generation". International Journal of Microwave and Wireless Technologies 3, n. 3 (25 marzo 2011): 383–89. http://dx.doi.org/10.1017/s1759078711000262.

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Abstract (sommario):

In this paper we propose a photonic technique for a reconfigurable microwave signal generation based on the beating of two laser modes coming from a regenerative fiber mode-locked laser (FMLL) into a photodiode. The excellent performance of this kind of pulsed laser guarantees high stability on the directly generated microwave signal even at ultrahigh frequencies (up to W band). Therefore, by using the proposed architecture, the performance of a reconfigurable full digital coherent radar system can be enhanced for example in terms of moving target indicator (MTI) improvement factor and analog to digital converter maximum signal to noise ratio. Differently from the conventional radar oscillators, whose performance strongly deteriorate with increasing frequencies, the photonic radio frequency (RF) generation always shows an excellent spectral purity. Moreover, thanks to the achievable high repetition rates and the coherence properties of the FMLL, this laser scheme has also been proposed for digitizing, directly at RF, the received signal by electro-optical sampling. Thus the advantage of using just one device for signal generation in both the transmitter and receiver chain, makes the proposed solution a cost-effective architecture for microwave signal generation.

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