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Articoli di riviste sul tema "Optical Phase Noise Measurement"

Autore: Grafiati

Pubblicato: 7 dicembre 2024

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1

Horstman, Luke, e Jean-Claude Diels. "Intracavity Measurement Sensitivity Enhancement without Runaway Noise". Sensors 21, n. 24 (19 dicembre 2021): 8473. http://dx.doi.org/10.3390/s21248473.

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A method to increase the sensitivity of an intracavity differential phase measurement that is not made irrelevant by a larger increase of noise is explored. By introducing a phase velocity feedback by way of a resonant dispersive element in an active sensor in which two ultrashort pulses circulate, it is shown that the measurement sensitivity is elevated without significantly increasing the Petermann excess noise factor. This enhancement technique has considerable implications for any optical phase based measurement; from gyroscopes and accelerometers to magnetometers and optical index measurements. Here we describe the enhancement method in the context of past dispersion enhancement studies including the recent work surrounding non-Hermitian quantum mechanics, justify the method with a theoretical framework (including numerical simulations), and propose practical applications.

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2

Rodríguez-García, M. A., e F. E. Becerra. "Adaptive Phase Estimation with Squeezed Vacuum Approaching the Quantum Limit". Quantum 8 (25 settembre 2024): 1480. http://dx.doi.org/10.22331/q-2024-09-25-1480.

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Phase estimation plays a central role in communications, sensing, and information processing. Quantum correlated states, such as squeezed states, enable phase estimation beyond the shot-noise limit, and in principle approach the ultimate quantum limit in precision, when paired with optimal quantum measurements. However, physical realizations of optimal quantum measurements for optical phase estimation with quantum-correlated states are still unknown. Here we address this problem by introducing an adaptive Gaussian measurement strategy for optical phase estimation with squeezed vacuum states that, by construction, approaches the quantum limit in precision. This strategy builds from a comprehensive set of locally optimal POVMs through rotations and homodyne measurements and uses the Adaptive Quantum State Estimation framework for optimizing the adaptive measurement process, which, under certain regularity conditions, guarantees asymptotic optimality for this quantum parameter estimation problem. As a result, the adaptive phase estimation strategy based on locally-optimal homodyne measurements achieves the quantum limit within the phase interval of [0,π/2). Furthermore, we generalize this strategy by including heterodyne measurements, enabling phase estimation across the full range of phases from [0,π), where squeezed vacuum allows for unambiguous phase encoding. Remarkably, for this phase interval, which is the maximum range of phases that can be encoded in squeezed vacuum, this estimation strategy maintains an asymptotic quantum-optimal performance, representing a significant advancement in quantum metrology.

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3

Krasionov, I. I., e L. V. Il’ichev. "Noise-oriented quantum optical gyrometry". Quantum Electronics 52, n. 2 (1 febbraio 2022): 127–29. http://dx.doi.org/10.1070/qel17979.

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Abstract By the example of an optical gyroscope scheme, a new method for improving the accuracy of phase measurements is considered. In the rotation-recording Mach – Zehnder interferometer, a two-mode squeezed vacuum is used as an input state. This does not allow realising the traditional scheme, since the average value of the difference signal at the output is always zero. However, it is shown that information about the magnitude of the rotation angular velocity of the instrument reference frame is contained in the noise level of the difference signal. The possibility of reaching the Heisenberg limit of the measurement accuracy is demonstrated.

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4

Shi, Jingzhan, Fangzheng Zhang, De Ben e Shilong Pan. "Photonic-assisted single system for microwave frequency and phase noise measurement". Chinese Optics Letters 18, n. 9 (2020): 092501. http://dx.doi.org/10.3788/col202018.092501.

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5

Chen, Jia-Qi, Chao Chen, Jing-Jing Sun, Jian-Wei Zhang, Zhao-Hui Liu, Li Qin, Yong-Qiang Ning e Li-Jun Wang. "Linewidth Measurement of a Narrow-Linewidth Laser: Principles, Methods, and Systems". Sensors 24, n. 11 (5 giugno 2024): 3656. http://dx.doi.org/10.3390/s24113656.

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Narrow-linewidth lasers mainly depend on the development of advanced laser linewidth measurement methods for related technological progress as key devices in satellite laser communications, precision measurements, ultra-high-speed optical communications, and other fields. This manuscript provides a theoretical analysis of linewidth characterization methods based on the beat frequency power spectrum and laser phase noise calculations, and elaborates on existing research of measurement technologies. In addition, to address the technical challenges of complex measurement systems that commonly rely on long optical fibers and significant phase noise jitter in the existing research, a short-delay self-heterodyne method based on coherent envelope spectrum demodulation was discussed in depth to reduce the phase jitter caused by 1/f noise. We assessed the performance parameters and testing conditions of different lasers, as well as the corresponding linewidth characterization methods, and analyzed the measurement accuracy and error sources of various methods.

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6

Fischer, Marc, Marcus Petz e Rainer Tutsch. "Statistical characterization of evaluation strategies for fringe projection systems by means of a model-based noise prediction". Journal of Sensors and Sensor Systems 6, n. 1 (6 aprile 2017): 145–53. http://dx.doi.org/10.5194/jsss-6-145-2017.

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Abstract. For optical 3-D measurement systems, camera noise is the dominant uncertainty factor when optically cooperative surfaces are measured in a stable and controlled environment. In industrial applications repeated measurements are seldom executed for this kind of measurement system. This leads to statistically suboptimal results in subsequent evaluation steps as the important information about the quality of individual measurement points is lost. In this work it will be shown that this information can be recovered for phase measuring optical systems with a model-based noise prediction. The capability of this approach will be demonstrated exemplarily for a fringe projection system and it will be shown that this method is indeed able to generate an individual estimate for the spatial stochastic deviations resulting from image sensor noise for each measurement point. This provides a valuable tool for a statistical characterization and comparison of different evaluation strategies, which is demonstrated exemplarily for two different triangulation procedures.

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7

Bengalskii, Danil M., Danil R. Kharasov, Edgard A. Fomiryakov, Sergei P. Nikitin, Oleg E. Nanii e Vladimir N. Treshchikov. "Characterization of Laser Frequency Stability by Using Phase-Sensitive Optical Time-Domain Reflectometry". Photonics 10, n. 11 (4 novembre 2023): 1234. http://dx.doi.org/10.3390/photonics10111234.

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A new method to measure laser phase noise and frequency stability based on the phase-sensitive optical time-domain reflectometry is proposed. In this method, the laser under test is utilized in a phase-sensitive optical time-domain reflectometer, which employs phase-modulated dual pulses and acts as an optical frequency discriminator: laser frequency fluctuations are deduced from the analysis of the reflectometer data corresponded to phase fluctuations along the vibration-damped and thermally insulated fiber spool. The measurement results were validated by comparison with direct optical heterodyning of the tested and more coherent reference lasers. The use of dual pulses generated by an acousto-optic modulator makes it easy to adjust the time delay during measurements, which distinguishes favorably the proposed method from standard optical frequency discriminators. The method is suitable for testing highly coherent lasers and qualifying their parameters such as linear drift rate, random frequency walk rate, white frequency noise (which is directly related to laser instantaneous linewidth), and flicker noise level.

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8

van Ardenne, A., e W. Melis. "Quasi-optical measurement of carcinotron phase noise at 350 GHz". Electronics Letters 24, n. 23 (1988): 1411. http://dx.doi.org/10.1049/el:19880964.

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9

Xu, Hao, Haitao Wu, Dong Hou, Haoyuan Lu, Zhaolong Li e Jianye Zhao. "Yoctosecond Timing Jitter Sensitivity in Tightly Synchronized Mode-Locked Ti:Sapphire Lasers". Photonics 9, n. 8 (12 agosto 2022): 569. http://dx.doi.org/10.3390/photonics9080569.

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Higher sensitivity in timing jitter measurement has great importance in studies related to precise measurements. Timing jitter noise floors contribute one of the main parts in existing measurements. In this article, a phase error signal is obtained by superposition of outputs of two optical heterodyne discrimination apparatus to suppress the noise floor. Excess phase noise of the electrical amplifier is avoided. We demonstrate 2.6 × 10−14 fs2/Hz (~160 ys/√Hz) timing jitter noise floor between two identical 99 MHz repetition-rate mode-locked Ti:sapphire lasers after their repetition rates are tightly synchronized. The performance is extensible to reach an integrated timing jitter resolution of one attosecond.

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10

Duong, Chen e Chen. "Absolute Depth Measurement Using Multiphase Normalized Cross-Correlation for Precise Optical Profilometry". Sensors 19, n. 21 (28 ottobre 2019): 4683. http://dx.doi.org/10.3390/s19214683.

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In a multifrequency phase-shifting (MFPS) algorithm, the temporal phase unwrapping algorithm can extend the unambiguous phase range by transforming the measurement range from a short fringe pitch into an extended synthetic pitch of two different frequencies. However, this undesirably amplifies the uncertainty of measurement, with each single-frequency phase map retaining its measurement uncertainty, which is carried over to the final unwrapped phase maps in fringe-order calculations. This article analyzes possible causes and proposes a new absolute depth measurement algorithm to minimize the propagation of measurement uncertainty. Developed from normalized cross-correlation (NCC), the proposed algorithm can minimize wrong fringe-order calculations in the MFPS algorithm. The experimental results demonstrated that the proposed measurement method could effectively calibrate the wrong fringe order. Moreover, some extremely low signal-to-noise ratio (SNR) regions of a captured image could be correctly reconstructed (for surface profiles). The present findings confirmed measurement precision at one standard deviation below 5.4 µm, with an absolute distance measurement of 16 mm. The measurement accuracy of the absolute depth could be significantly improved from an unacceptable level of measured errors down to 0.5% of the overall measuring range. Additionally, the proposed algorithm was capable of extracting the absolute phase map in other optical measurement applications, such as distance measurements using interferometry.

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11

Ma, Cheng, Evan M. Lally e Anbo Wang. "Toward Eliminating Signal Demodulation Jumps in Optical Fiber Intrinsic Fabry–Perot Interferometric Sensors". Journal of Lightwave Technology 29, n. 13 (luglio 2011): 1913–19. http://dx.doi.org/10.1109/jlt.2011.2144957.

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Fiber optic Fabry-Perot sensors are commonly interrogated by spectral interferometric measurement of optical path difference (OPD). Spurious jumps in sensor output, previously attributed to noise, are often observed in OPD-based measurements. Through analysis and experimentation based on intrinsic Fabry-Perot interferometric (IFPI) sensors, we show that these discontinuities are actually caused by a time-varying interferogram phase term. We identify several physical causes for varying initial phase and derive a threshold value at which it begins to cause errors in the sensor output. Finally, we present a total phase measurement method as an alternative to OPD-based techniques to reduce the occurrence of output signal jumps.

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12

Lipiński, Marcin, Przemysław Krehlik, Łukasz Śliwczyński, Łukasz Buczek e Jacek Kołodziej. "Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise". Metrology and Measurement Systems 23, n. 2 (1 giugno 2016): 309–16. http://dx.doi.org/10.1515/mms-2016-0024.

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Abstract The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F) fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

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13

Kikuchi, K., C. E. Zah e T. P. Lee. "Measurement and analysis of phase noise generated from semiconductor optical amplifiers". IEEE Journal of Quantum Electronics 27, n. 3 (marzo 1991): 416–22. http://dx.doi.org/10.1109/3.81340.

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14

Molina-Fern�ndez, I., e J. de-Oliva-Rubio. "Effects of phase noise in an optical six-port measurement technique". Optics Express 13, n. 7 (2005): 2475. http://dx.doi.org/10.1364/opex.13.002475.

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15

Hong, Jun, An-min Liu e Jian Guo. "Study on low-phase-noise optoelectronic oscillator and high-sensitivity phase noise measurement system". Journal of the Optical Society of America A 30, n. 8 (15 luglio 2013): 1557. http://dx.doi.org/10.1364/josaa.30.001557.

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16

Wan, Feng, Baojian Wu, Feng Wen e Kun Qiu. "In-Band OSNR Measurement Method for All-Optical Regenerators in Optical Domain". Applied Sciences 9, n. 24 (11 dicembre 2019): 5438. http://dx.doi.org/10.3390/app9245438.

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We propose an in-band measurement method of optical signal-to-noise ratio (OSNR) output from an all-optical regeneration system with a nonlinear power transfer function (PTF) according to the fact that there are different average gains of signal and noise. For the all-optical quadrature phase-shift keying (QPSK) regenerator as an example, the output OSNR is derived from the input OSNR and the total gain of the degraded QPSK signal. Our simulation shows that the OSNR results obtained by this method are in agreement with those calculated from the error vector magnitude (EVM) formula. The method presented here has good applicability for different data rates but is also useful for analyzing the OSNR degradation of other nonlinear devices in optical communication links.

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17

Hu Xiao, 肖虎, 王小林 Xiaolin Wang, 马阎星 Yanxing Ma, 何兵 Bing He, 周朴 Pu Zhou, 周军 Jun Zhou e 许晓军 Xiaojun Xu. "Phase noise measurement of high-power fiber amplifiers". Chinese Optics Letters 9, n. 4 (2011): 041404–41407. http://dx.doi.org/10.3788/col201109.041404.

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18

Khayatzadeh, Ramin, Habeb Rzaigui, Julien Poette e Beatrice Cabon. "Accurate Millimeter-Wave Laser Phase Noise Measurement Technique". IEEE Photonics Technology Letters 25, n. 13 (luglio 2013): 1218–21. http://dx.doi.org/10.1109/lpt.2013.2263378.

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19

Li, Huicong, Minggan Lou, Wenzhu Huang e Wentao Zhang. "Real-Time Measurement and Uncertainty Evaluation of Optical Path Difference in Fiber Optic Interferometer Based on Auxiliary Interferometer". Sensors 24, n. 7 (22 marzo 2024): 2038. http://dx.doi.org/10.3390/s24072038.

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Optical interferometers are the main elements of interferometric sensing and measurement systems. Measuring their optical path difference (OPD) in real time and evaluating the measurement uncertainty are key to optimizing system noise and ensuring system consistency. With the continuous sinusoidal wavelength modulation of the laser, real-time OPD measurement of the main interferometer is achieved through phase comparison of the main and auxiliary interferometers. The measurement uncertainty of the main interferometer OPD is evaluated. It is the first evaluation of the impact of different auxiliary interferometer calibration methods on OPD measurements. A homodyne quadrature laser interferometer (HQLI) is used as the main interferometer, and a 3 × 3 interferometer is used as the auxiliary interferometer. The calibration of the auxiliary interferometer using optical spectrum analyzer scanning and ruler measurement is compared. The evaluation shows that the auxiliary interferometer is the most significant source of uncertainty and causes the total uncertainty to increase linearly with increasing OPD. It is proven that a high-precision calibration and large-OPD auxiliary interferometer can improve the real-time accuracy of OPD measurements based on the auxiliary interferometer. The scheme can determine the minimum uncertainty to optimize the system noise and consistency for vibration, hydroacoustic, and magnetic field measurements with OPDs of the ~m level.

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20

Tian, Haochen, Youjian Song e Minglie Hu. "Noise Measurement and Reduction in Mode-Locked Lasers: Fundamentals for Low-Noise Optical Frequency Combs". Applied Sciences 11, n. 16 (20 agosto 2021): 7650. http://dx.doi.org/10.3390/app11167650.

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After five decades of development, mode-locked lasers have become significant building blocks for many optical systems in scientific research, industry, and biomedicine. Advances in noise measurement and reduction are motivated for both shedding new light on the fundamentals of realizing ultra-low-noise optical frequency combs and their extension to potential applications for standards, metrology, clock comparison, and so on. In this review, the theoretical models of noise in mode-locked lasers are first described. Then, the recent techniques for timing jitter, carrier-envelope phase noise, and comb-line noise measurement and their stabilization are summarized. Finally, the potential of the discussed technology to be fulfilled in novel optical frequency combs, such as electro-optic (EO) modulated combs, microcombs, and quantum cascade laser (QCL) combs, is envisioned.

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21

Magri, Vanessa P. R., Odylio D. Aguiar, Claudia B. M. P. Leme, Marbey M. Mosso, S. R. Furtado, Juliana B. Carvalho e Jorge A. M. Souza. "Single loop phase noise measurement of microwave oscillators". Microwave and Optical Technology Letters 56, n. 10 (22 luglio 2014): 2304–10. http://dx.doi.org/10.1002/mop.28577.

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22

Delehaye, Marion, Jacques Millo, Pierre-Yves Bourgeois, Lucas Groult, Rodolphe Boudot, Enrico Rubiola, Emmanuel Bigler, Yann Kersale e Clement Lacroute. "Residual Phase Noise Measurement of Optical Second Harmonic Generation in PPLN Waveguides". IEEE Photonics Technology Letters 29, n. 19 (1 ottobre 2017): 1639–42. http://dx.doi.org/10.1109/lpt.2017.2741667.

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23

Plumb, D. M., e J. M. Harris. "Absorbance Measurements in Optically Inhomogeneous Samples Using Phase-Conjugate Thermal Lens Spectroscopy". Applied Spectroscopy 46, n. 9 (settembre 1992): 1346–53. http://dx.doi.org/10.1366/0003702924123827.

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The optical phase conjugation properties of a BaTiO3 crystal are employed in a thermal lens experiment to measure small absorbance values of optically inhomogeneous samples. The sensitivity of the thermal lens, together with the beam reconstruction capabilities of phase conjugation, allows measurement of absorbances as low as 1.2 × 10−5 in the presence of large-amplitude spatial noise. A model which describes the behavior of an ordinary thermal lens could be used to evaluate the behavior of the phase-conjugate thermal lens response. Controlled phase-front perturbations generated by the thermal lens are used to characterize the influence of optical path distortions on phase-conjugate reflectivity.

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24

Bartolo, Robert E., Alan B. Tveten e Anthony Dandridge. "Thermal Phase Noise Measurements in Optical Fiber Interferometers". IEEE Journal of Quantum Electronics 48, n. 5 (maggio 2012): 720–27. http://dx.doi.org/10.1109/jqe.2012.2190717.

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25

Wang, Weitao, Chen Wang, Shuai Qu, Haifeng Qi, Zhiqiang Song, Pengbo Jiang, Jian Guo, Ying Shang, Jiasheng Ni e Gangding Peng. "Research on the Linear Demodulation Range and Background Noise of Fiber-Optic Interferometer System". Photonics 10, n. 3 (7 marzo 2023): 283. http://dx.doi.org/10.3390/photonics10030283.

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The linear demodulation range and background noise of the Michelson interferometer system are investigated with a laser phase noise measurement system. We have theoretically and experimentally analyzed the performance of the interferometer system by changing the frequency modulation amplitude of the laser and the optical path difference (OPD) of the interferometer, respectively. It is shown that the linear demodulation range of the Michelson interferometer system is finite, which depends on the parameters of the system, such as the sample frequency, the delay time between two interferometer arms, and the system bandwidth. Furthermore, the experimental results indicate that the background noise of the interferometer system can be reduced by using a sufficiently long OPD so that the smaller true phase information can be detected with the demodulation system. The parameters of the measurement system could be optimized to satisfy the demand of the phase demodulation with different levels, which is of great significance for the phase monitoring interrogator, such as fiber-optical interferometer sensors and distributed acoustic sensors.

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26

Yu, Zhijie, Yang Lu, Xiaoyang Hu e Zhou Meng. "Polarization dependence of the noise of phase measurement based on phase-sensitive OTDR". Journal of Optics 19, n. 12 (1 novembre 2017): 125602. http://dx.doi.org/10.1088/2040-8986/aa924e.

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27

Zhao, Xiaxia, Rong Mo, Zhiyong Chang e Jin Lu. "A gamma correction method based on constant-intensity images in phase-measuring profilometry". Insight - Non-Destructive Testing and Condition Monitoring 62, n. 5 (1 maggio 2020): 256–63. http://dx.doi.org/10.1784/insi.2020.62.5.256.

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Phase-measuring profilometry (PMP) is an important technique for image analysis in optical non-destructive testing (NDT). Its measurement accuracy is significantly affected by gamma distortion in the projector, which makes the projected sinusoidal fringe patterns non-sinusoidal. In order to address this issue, a generic gamma non-linearity model based on constant-intensity images is proposed in this paper. In the proposed model, system defocus and noise are considered and analysed. It is demonstrated through theoretical derivation that the constant-intensity images remain unchanged, with no additional frequency being produced. For this reason, system defocus is not modelled in the proposed gamma calibration model and the related defocus parameters need not be calculated, which reduces the complexity of the calculation. Any noise that exists in the optical measurement system is another main factor influencing the greyscale levels of the image. A mutual information (MI)-based denoising method is proposed to reduce the noise and improve the accuracy of the gamma calibration. Furthermore, with the defocus analysis and the noise reducing method, a robust pixel-wise gamma calibration method is introduced. The experimental results in this paper show that the proposed gamma calibration method is able to accurately calibrate the gamma non-linearity of the system. Moreover, the phase precision is significantly improved and a higher quality measurement is achieved for the measured surfaces.

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28

YU, LI-PING, JIAN-CHEN GUO, LI-DEK CHOU, TE-LUN MA, JHENG-SYONG WU, JIANN-DER LEE e CHIEN CHOU. "POLARIZATION-SENSITIVE OPTICAL COHERENCE TOMOGRAPHY USING A MODIFIED BALANCE DETECTOR". Journal of Innovative Optical Health Sciences 05, n. 04 (ottobre 2012): 1250024. http://dx.doi.org/10.1142/s1793545812500241.

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In conventional polarization-sensitive optical coherence tomography (PS-OCT), phase retardation is obtained by the amplitude of P and S polarization only, and the fast axis angle is obtained by the phase difference in P and S polarizations via Hilbert transformation. In this paper, we proposed a modified PS-OCT setup in which the phase retardation and fast axis angle are simply expressed as the function of the amplitude of P and S polarization and their differential signal. Due to the common-path feature between the two channels of P and S polarization, the fluctuation in the measurement of phase retardation and fast axis angle caused by excess noise and phase noise from the laser source can be reduced by the differential signal of P and S polarization via a modified balance detector. Thus, the signal of phase retardation and fast angle axis in the deep layer of a porcine sample can be improved.

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29

Zhu, Mingda, Xiaoxin Liu, Yaping Wang, Jianhua Bi, Yudong Xu e Yingcong Zhu. "Research and Design of Photoelectric Converter for Quantum Gravimeter". Journal of Physics: Conference Series 2383, n. 1 (1 dicembre 2022): 012032. http://dx.doi.org/10.1088/1742-6596/2383/1/012032.

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In the control system of a quantum gravimeter, the optical signal containing phase information is weak and usually at the nV level. This situation puts forward high requirements for the measurement performance of the system. As the coupling input component of the measurement system, the noise level of the preamplifier has a dramatic influence on the noise performance. In this paper, the input current signal is provided by the photodiode. According to the photodiode output characteristics, we design three preamplifiers with different gain and bandwidth, which is verified by the optical system. Under the condition of meeting the design requirements, the noise performance is compared with the common commercial detector Model 2307. The results show that the noise performance of the photoelectric converter designed in this paper is about 1.5 times that of model 2307.

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Stepanov, Konstantin V., Andrey A. Zhirnov, Tatyana V. Gritsenko, Roman I. Khan, Kirill I. Koshelev, Cesare Svelto e Alexey B. Pnev. "Instability Compensation of Recording Interferometer in Phase-Sensitive OTDR". Sensors 24, n. 11 (23 maggio 2024): 3338. http://dx.doi.org/10.3390/s24113338.

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In the paper, a new method of phase measurement error suppression in a phase-sensitive optical time domain reflectometer is proposed and experimentally proved. The main causes of phase measurement errors are identified and considered, such as the influence of the recording interferometer instabilities and laser wavelength instability, which can cause inaccuracies in phase unwrapping. The use of a Mach–Zender interferometer made by 3 × 3 fiber couplers is proposed and tested to provide insensitivity to the recording interferometer and laser source instabilities. It is shown that using all three available photodetectors of the interferometer, instead of just one pair, achieves significantly better accuracy in the phase unwrapping. A novel compensation scheme for accurate phase measurements in a phase-sensitive optical time domain reflectometer is proposed, and a comparison of the measurement signals with or without such compensation is shown and discussed. The proposed method, using three photodetectors, allows for very good compensation of the phase measurement errors arising from common-mode noise from the interferometer and laser source, providing a significant improvement in signal detection. In addition, the method allows the tracking of slow temperature changes in the monitored fiber/object, which is not obtainable when using a simple low-pass filter for phase unwrapping error reduction, as is customary in several systems of this kind.

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Mitrofanov, Oleg. "Laser excess noise reduction in optical phase-shift measurements". Applied Optics 42, n. 14 (10 maggio 2003): 2526. http://dx.doi.org/10.1364/ao.42.002526.

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Lu, Xin, e Peter James Thomas. "Phase Error Evaluation via Differentiation and Cross-Multiplication Demodulation in Phase-Sensitive Optical Time-Domain Reflectometry". Photonics 10, n. 5 (28 aprile 2023): 514. http://dx.doi.org/10.3390/photonics10050514.

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Phase-sensitive optical time-domain reflectometry (φOTDR) is a technology for distributed vibration sensing, where vibration amplitudes are determined by recovering the phase of the backscattered light. Measurement noise induces phase errors, which degrades sensing performance. The phase errors, using a differentiation and cross-multiplication (DCM) algorithm, are investigated theoretically and experimentally in a φOTDR system based on a phase retrieval configuration consisting of an imbalanced Mach–Zehnder interferometer (IMZI) and a 3 × 3 coupler. Analysis shows that phase error is highly dependent on the AC component of the obtained signal, essentially being inversely proportional to the product of the power of the light backscattered from two locations. An analytical expression was derived to estimate the phase error and was confirmed by experiment. When applied to the same measurement data, the error is found to be slightly smaller than that obtained using in-phase/quadrature (I/Q) demodulation. The error, however, increases for longer measurement times.

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Zhu, Dengjian, Fangzheng Zhang, Pei Zhou, Dan Zhu e Shilong Pan. "Wideband Phase Noise Measurement Using a Multifunctional Microwave Photonic Processor". IEEE Photonics Technology Letters 26, n. 24 (15 dicembre 2014): 2434–37. http://dx.doi.org/10.1109/lpt.2014.2358617.

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Hao, Lili, Rui Chang, Xiaokai Hou, Jun He e Junmin Wang. "Narrow-Linewidth 852-nm DBR-LD with Self-Injection Lock Based on High-Finesse Optical Cavity Filtering". Photonics 10, n. 8 (16 agosto 2023): 936. http://dx.doi.org/10.3390/photonics10080936.

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Abstract (sommario):

Narrow-linewidth lasers have a high spectral purity, long coherent length, and low phase noise, so they have important applications in atomic clocks, precision measurement, and quantum computing. We inject a transmitted laser from a narrow-linewidth (∼15 kHz) flat-concave Fabry–Perot (F-P) cavity made from ultra-low expansion (ULE) optical glass into an 852 nm distributed Bragg reflector-type laser diode (DBR-LD), of which the comprehensive linewidth is 1.67 MHz for the free running case. With an increase in the self-injection power, the laser linewidth gradually narrows, and the injection locking current range gradually increases. The narrowest linewidth measured by the delayed frequency-shifted self-heterodyne (DFSSH) method is about 365 Hz, which is about 1/4500 of the linewidth for the free running case. Moreover, to characterize the laser phase noise, we use a detuned F-P cavity to measure the conversion signal from the laser phase noise to the intensity noise for both the free running case and the self-injection lock case. The laser phase noise for the self-injection lock case is significantly suppressed in the analysis frequency range of 0.1–10 MHz compared to the free running case. In particular, the phase noise is suppressed by more than 30 dB at an analysis frequency of 100 kHz.

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Salzenstein, Patrice. "Frequency and temperature control for complex system engineering in optoelectronics and electronics: an overview". International Journal for Simulation and Multidisciplinary Design Optimization 11 (2020): 7. http://dx.doi.org/10.1051/smdo/2020001.

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To take advantage of the physical principles of determining parameters, such as frequency stability, noise and also alignment of optical signals, it is necessary to control complex systems. This work allows explaining it through various concrete cases such as the determination of phase noise of microwave oscillators, the control of the temperature of the manufacturing process of optical components. We also discuss the estimation of the uncertainty associated with the measurement results, as it is fundamental to control the error range.

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Karl, Sebastian, Andreas Zmija, Stefan Richter, Naomi Vogel, Dmitry Malyshev, Adrian Zink, Thilo Michel, Gisela Anton, Joachim von Zanthier e Stefan Funk. "Comparing different approaches for stellar intensity interferometry". Monthly Notices of the Royal Astronomical Society 512, n. 2 (23 febbraio 2022): 1722–29. http://dx.doi.org/10.1093/mnras/stac489.

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ABSTRACT Stellar intensity interferometers correlate photons within their coherence time and could overcome the baseline limitations of existing amplitude interferometers. Intensity interferometers do not rely on phase coherence of the optical elements and thus function without high-grade optics and light combining delay lines. However, the coherence time of starlight observed with realistic optical filter bandwidths ($\gt {0.1}\, {\rm nm}$) is usually much smaller than the time resolution of the detection system ($\gt {10}\, {\rm ps}$), resulting in a greatly reduced correlation signal. Reaching high signal-to-noise ratio in a reasonably short measurement time can be achieved in different ways: either by increasing the time resolution, which increases the correlation signal height, or by increasing the photon rate, which decreases statistical uncertainties of the measurement. We present laboratory measurements employing both approaches and directly compare them in terms of signal-to-noise ratio. A high-time-resolution interferometry setup designed for small-to-intermediate-sized optical telescopes and thus lower photon rates (diameters $\lt \,$some metres) is compared to a setup capable of measuring high photon rates, which is planned to be installed at Cherenkov telescopes with dish diameters of $\gt {10}\, {\rm m}$. We use a xenon lamp as a common light source simulating starlight. Both setups measure the expected correlation signal and work at the expected shot-noise limit of statistical uncertainties for measurement times between 10 min and 23 h. We discuss the quantitative differences in the measurement results and give an overview of suitable operation regimes for each of the interferometer concepts.

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Camatel, Stefano, e Valter Ferrero. "Phase Noise Power Spectral Density Measurement of Narrow Linewidth CW Lasers Using an Optical Phase-Locked Loop". IEEE Photonics Technology Letters 18, n. 23 (dicembre 2006): 2529–31. http://dx.doi.org/10.1109/lpt.2006.887206.

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38

Litchford, R. J., F. Sun, J. D. Few e J. W. L. Lewis. "Optical Measurement of Gas Turbine Engine Soot Particle Effluents". Journal of Engineering for Gas Turbines and Power 120, n. 1 (1 gennaio 1998): 69–76. http://dx.doi.org/10.1115/1.2818089.

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This paper addresses optical-based techniques for measuring soot particulate loading in the exhaust stream of gas turbine engines. The multi-angle scattering and multi-wavelength extinction of light beams by ensembles of submicrometer soot particles was investigated as a diagnostic means of inferring particle field characteristics. This is, the particle size distribution function and particle number density were deduced using an innovative downhill simplex inversion algorithm for fitting the deconvolved Mie-based scattering/extinction integral to the measured scattering/extinction signals. In this work, the particle size distribution was characterized by the widely accepted two-parameter log-normal distribution function, which is fully defined with the specification of the mean particle diameter and the standard deviation of the distribution. The accuracy and precision of the algorithm were evaluated for soot particle applications by applying the technique to noise-perturbed synthetic data in which the signal noise component is obtained by Monte Carlo sampling of Gaussian distributed experimental errors of 4, 6, and 10 percent. The algorithm was shown to yield results having an inaccuracy of less than 10 percent for the highest noise levels and an imprecision equal to or less than the experimental error. Multi-wavelength extinction experiments with a laboratory bench-top burner yielded a mean particle diameter of 0.039 μm and indicated that molecular absorption by organic vapor-phase molecules in the ultraviolet region should not significantly influence the measurements. A field demonstration test was conducted on one of the JT-12D engines of a Sabre Liner jet aircraft. This experiment yielded mean diameters of 0.040 μm and 0.036 μm and standard deviations of 0.032 μm and 0.001 μm for scattering and extinction methods, respectively. The total particulate mass flow rate at idle was estimated to be 0.54 kg/h.

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Ng, Hoi-Yee, Kim-Fung Tsang e Chung-Ming Yuen. "Phase-noise measurement of free-running microwave voltage-controlled oscillators". Microwave and Optical Technology Letters 45, n. 3 (2005): 216–17. http://dx.doi.org/10.1002/mop.20773.

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40

Han, Ya-Shuai, Xiao Zhang, Zhao Zhang, Jun Qu e Jun-Min Wang. "Analysis of squeezed light source in band of alkali atom transitions based on cascaded optical parametric amplifiers". Acta Physica Sinica 71, n. 7 (2022): 074202. http://dx.doi.org/10.7498/aps.71.20212131.

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Abstract (sommario):

The squeezed light field in the band of alkali metal atomic transitions is an important quantum resource in the field of quantum information and precision measurement. The wavelengths of atomic transition lines (760–860 nm) are relatively short. Limited by the gray-tracking effect of nonlinear crystals, the squeezing degree of the squeezed light in this band generated by the optical parametric amplifiers is low. Now, the squeezing is about 3–5 dB. Considering the problems in the experimental generation of the squeezed light at the wavelengths of atomic transitions, the variation law of quantum noise of the light field output from the single optical parametric amplifier with its physical parameters is studied theoretically, and the optimal physical parameters are obtained. To further improve the squeezing in the band of alkali metal atomic transitions, the cascaded optical parametric amplifiers are considered. Based on the basic theory of the optical parametric amplifiers, the theoretical model of the cascaded optical parametric amplifiers is constructed, in which the optical loss and phase noise of the cascaded optical loops are considered. Based on this, the quantum noise characteristics of the light field output from the cascaded system versus the optical loss and phase noise are analyzed at the frequencies of 2 MHz and 100 kHz, respectively. It is found that for the squeezing at 2 MHz, cascading 2 to 3 optical parametric amplifiers can significantly improve the squeezing under the premise of the low optical path loss and phase noise; for the squeezing in the low-frequency band, the enhancement of the squeezing for the cascaded system is quite weak. Under the current experimental parameters, the squeezing at 2 MHz of the squeezed light on rubidium resonance can be improved from –5 dB to –7 dB by cascading another DOPA. For the squeezing at low frequency band, the cascaded system proves to be useless, and the efforts should be made to reduce the technique noise in the low frequency band. Furthermore, the quantum limit and spectral characteristics of the squeezed light field output from the cascaded system are further explored. This study can provide reference and guidance for the improvement in the squeezing degree of the band of atomic transitions.

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Anthur, A. P., e D. Venkitesh. "High‐resolution technique for simultaneous measurement of phase noise of multi‐wavelength optical systems". Electronics Letters 49, n. 18 (agosto 2013): 1165–67. http://dx.doi.org/10.1049/el.2013.1784.

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Yamaguchi, Ichirou. "Shape and deformation measurements of rough surfaces by phase-shifting digital holography". Photonics Letters of Poland 13, n. 4 (30 dicembre 2021): 70. http://dx.doi.org/10.4302/plp.v13i4.1127.

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Abstract (sommario):

In digital holography recording as reconstruction of holograms are performed digitally by modern photonic devices to increase of optical non-contacting measurements of various kinds of surfaces including both specular and rough surfaces. In this article we discusses these features of digital holography using phase shifting techniques that has much extended its capabilities. Full Text: PDF ReferencesG. Bruning, D.R. Herriott, J.E. Gallagher, D.P. Rosenfeld, A.D. White, D.J. Brangaccio, "Digital Wavefront Measuring Interferometer for Testing Optical Surfaces and Lenses", Appl. Opt. 13, 2693 (1974). CrossRef I. Yamaguchi, T. Zhang, "Phase-shifting digital holography", Opt. Lett. 22, 1268 (1997). CrossRef F. Zhang, I. Yamaguchi, L.P. Yaroslavsky, "Algorithm for reconstruction of digital holograms with adjustable magnification", Opt. Lett. 29, 1668 (2004). CrossRef I. Yamaguchi, "Holography, speckle, and computers", Optics and Lasers in Engineering 39, 411 (2003). CrossRef I. Yamaguchi, M. Yokota, "Speckle noise suppression in measurement by phase-shifting digital holography", Opt. Eng. 48 085602 (2009). CrossRef I. Yamaguchi, J. Kato, S. Ohta, "Surface Shape Measurement by Phase-Shifting Digital Holography", Opt. Rev. 8, 85 (2001). CrossRef I. Yamaguchi, J. Kato, H. Matsuzaki, "Measurement of surface shape and deformation by phase-shifting image digital holography", Opt. Eng. 42, 1267 (2003). CrossRef F. Zhang, J.D.R. Valera, I. Yamaguchi, M. Yokota, G. Mills, "Vibration Analysis by Phase Shifting Digital Holography", Opt. Rev. 11, 5 (2004). CrossRef

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Tena Sánchez, Rubén, Fernando Rodríguez Varela, Lars J. Foged e Manuel Sierra Castañer. "Reconstruction of Relative Phase of Self-Transmitting Devices by Using Multiprobe Solutions and Non-Convex Optimization". Sensors 21, n. 7 (2 aprile 2021): 2459. http://dx.doi.org/10.3390/s21072459.

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Phase reconstruction is in general a non-trivial problem when it comes to devices where the reference is not accessible. A non-convex iterative optimization algorithm is proposed in this paper in order to reconstruct the phase in reference-less spherical multiprobe measurement systems based on a rotating arch of probes. The algorithm is based on the reconstruction of the phases of self-transmitting devices in multiprobe systems by taking advantage of the on-axis top probe of the arch. One of the limitations of the top probe solution is that when rotating the measurement system arch, the relative phase between probes is lost. This paper proposes a solution to this problem by developing an optimization iterative algorithm that uses partial knowledge of relative phase between probes. The iterative algorithm is based on linear combinations of signals when the relative phase is known. Phase substitution and modal filtering are implemented in order to avoid local minima and make the algorithm converge. Several noise-free examples are presented and the results of the iterative algorithm analyzed. The number of linear combinations used is far below the square of the degrees of freedom of the non-linear problem, which is compensated by a proper initial guess. With respect to noisy measurements, the top probe method will introduce uncertainties for different azimuth and elevation positions of the arch. This is modelled by considering the real noise model of a low-cost receiver and the results demonstrate the good accuracy of the method. Numerical results on antenna measurements are also presented. Due to the numerical complexity of the algorithm, it is limited to electrically small- or medium-size problems.

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Zykov, Alexey A., Alexander L. Matveyev, Lev A. Matveev, Maher Assaad e Vladimir Y. Zaitsev. "Computationally efficient adaptive optimization of vector-method parameters for phase-sensitive strain estimation in optical coherence elastography". Laser Physics Letters 21, n. 8 (2 luglio 2024): 085601. http://dx.doi.org/10.1088/1612-202x/ad552c.

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Abstract A new method for automatic adaptive optimization of strain estimation in phase-sensitive optical coherence tomography (OCT) is introduced. More specifically, this paper focuses on optimizing the estimation of strain using the vector method, in which OCT signals are treated as vectors in the complex plane. In phase-sensitive optical coherence elastography, the tissue strain is extracted from the interframe phase variation between the complex-valued scans acquired for the initial and deformed tissue. This phase variation is proportional to interframe displacements of scatterers and corresponds to the argument of the pixel-by-pixel product of the initial OCT scan and complex-conjugate deformed scan. Measurement noises and the so-called ‘speckle noise’ that are intrinsic to OCT scans cause degradation of the derived scan obtained by such multiplication. To mitigate the noise influence, complex-valued pixel amplitudes in the derived scan are usually averaged over a certain window. The interframe strain is found by estimating the gradient of the interframe phase difference. The noise influence on the strain estimation can also be reduced by increasing the scale over which the phase-variation gradient is estimated. However, choosing a too large window for preliminary averaging may significantly distort the reconstructed strain distribution. Similarly, a too large scale for gradient estimation may also cause errors in the estimated-strain magnitude and even its sign (because of possible phase wrapping). Therefore, appropriately performed adaptive choice of the strain-estimation parameters can greatly improve the quality of strain estimation. Here, we present a unified approach for adaptive choice of both the averaging-window size and gradient-estimation scale that were initially considered separately. The new method is computationally simplified but enables approximately the same strain-estimation quality, as demonstrated using both simulated and experimental OCT data.

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Ham, Byoung S. "Intensity-Product-Based Optical Sensing to Beat the Diffraction Limit in an Interferometer". Sensors 24, n. 15 (4 agosto 2024): 5041. http://dx.doi.org/10.3390/s24155041.

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The classically defined minimum uncertainty of the optical phase is known as the standard quantum limit or shot-noise limit (SNL), originating in the uncertainty principle of quantum mechanics. Based on the SNL, the phase sensitivity is inversely proportional to K, where K is the number of interfering photons or statistically measured events. Thus, using a high-power laser is advantageous to enhance sensitivity due to the K gain in the signal-to-noise ratio. In a typical interferometer, however, the resolution remains in the diffraction limit of the K = 1 case unless the interfering photons are resolved as in quantum sensing. Here, a projection measurement method in quantum sensing is adapted for classical sensing to achieve an additional K gain in the resolution. To understand the projection measurements, several types of conventional interferometers based on N-wave interference are coherently analyzed as a classical reference and numerically compared with the proposed method. As a result, the Kth-order intensity product applied to the N-wave spectrometer exceeds the diffraction limit in classical sensing and the Heisenberg limit in quantum sensing, where the classical N-slit system inherently satisfies the Heisenberg limit of π/N in resolution.

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Zibar, Darko, Hou-Man Chin, Yeyu Tong, Nitin Jain, Joel Guo, Lin Chang, Tobias Gehring, John E. Bowers e Ulrik L. Andersen. "Highly-Sensitive Phase and Frequency Noise Measurement Technique Using Bayesian Filtering". IEEE Photonics Technology Letters 31, n. 23 (1 dicembre 2019): 1866–69. http://dx.doi.org/10.1109/lpt.2019.2945051.

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47

Hu, Shaohua, Jing Zhang, Qun Liu, Linchangchun Bai, Xingwen Yi, Bo Xu e Kun Qiu. "Impacts of the measurement equation modification of the adaptive Kalman filter on joint polarization and laser phase noise tracking". Chinese Optics Letters 20, n. 2 (2022): 020603. http://dx.doi.org/10.3788/col202220.020603.

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48

Pascual-Cisneros, Guillermo, Francisco J. Casas e Patricio Vielva. "Optimization of a Microwave Polarimeter for Astronomy with Optical Correlation and Detection". Sensors 23, n. 5 (22 febbraio 2023): 2414. http://dx.doi.org/10.3390/s23052414.

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Abstract (sommario):

Cosmic Microwave Background (CMB) B-modes detection is the main focus of future CMB experiments because of the valuable information it contains, particularly to probe the physics of the very early universe. For this reason, we have developed an optimized polarimeter demonstrator sensitive to the 10–20 GHz band in which the signal received by each antenna is modulated into a Near Infrared (NIR) laser by a Mach–Zehnder modulator. Then, these modulated signals are optically correlated and detected using photonic back-end modules consisting of voltage-controlled phase shifters, a 90-degree optical hybrid, a pair of lenses, and an NIR camera. During laboratory tests, a 1/f-like noise signal related to the low phase stability of the demonstrator has been found experimentally. To solve this issue, we have developed a calibration method that allows us to remove this noise in an actual experiment, until obtaining the required accuracy level in the measurement of polarization.

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Zeng, Qilin, Zhengyi Zhao, Xianming Xiong, Hao Du, Wentao Zhang, Zhicheng Zhang, Peng Wang e Lihua Lei. "Design and Implementation of a Subnanometer Heterodyne Interference Signal Processing Algorithm with a Dynamic Filter". Sensors 22, n. 14 (20 luglio 2022): 5422. http://dx.doi.org/10.3390/s22145422.

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In this study, a subnanometer heterodyne interference signal processing algorithm with a dynamic filter is proposed. The algorithm can effectively reduce the measurement error caused by the noise introduced in the optical path and circuit. Because of the low signal−to−noise ratio of the measurement signal, a dynamic filter with variable coefficients is designed. The role of the bi−quadrature lock−in amplifier algorithm in the problem of different amplitudes among the measurement signal, reference signal, and uncertainty of the frequency difference of the dual−frequency laser is analyzed. With the aid of the heterodyne interferometry platform, the error in the solution results of the proposed algorithm and the conventional algorithm is compared. The results indicate that the maximum deviation of the phase increment of the algorithm does not exceed 6 mrad, the single−cycle phase difference can be subdivided by 1024, and the system resolution reaches 0.15 nm.

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Harraz, Sajede, Shuang Cong e Sen Kuang. "Optimal Noise Suppression of Phase Damping Quantum Systems via Weak Measurement". Journal of Systems Science and Complexity 32, n. 5 (4 gennaio 2019): 1264–79. http://dx.doi.org/10.1007/s11424-018-7392-5.

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