- 标题
- 摘要
- 关键词
- 实验方案
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Classification of the factors causing the change of the optical fiber strain by using the Brillouin reflectograms
摘要： A classification of the factors causing the change of the optical fiber strain by using the Brillouin reflectograms is considered. The differences of Brillouin reflectograms with strain along the optical waveguide are discussed under various impacts: temperature and mechanical longitudinal stretching. Reference Brillouin reflectograms for different kinds of optical fibers from the database are capable of improving a process of classification of potentially hazardous sections (sections of optical fibers with high mechanical strain or changed temperature) in the optical fiber. The results presented in this paper allow us on the basis of the analysis of Brillouin multi-reflectograms to identify a factor that has a predominant impact on the fiber strain in the investigated sections of the optical fibers in fiber optical communication lines.
关键词： Mandelstam – Brillouin scattering,Brillouin frequency shift,temperature,backscattered signal,Optical fiber,strain
更新于2025-09-16 10:30:52
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Improved algorithms for determining the strain of optical fibers using Brillouin reflectometers
摘要： The issues of improved algorithms for determining the strain of optical fibers using Brillouin reflectometers are investigated. Structure charts of devices for early diagnostics of optical fibers are presented. Adaptive algorithms for construction of Brillouin reflectograms: patterns of Brillouin frequency shift and strain distribution along the optical waveguide are considered. Reference Brillouin reflectograms for different optical fibers from the database are required to correctly detect the “problem” segments (segments of optical fibers with increased mechanical strain or with transformed temperature) in the optical waveguide.
关键词： Mandelstam – Brillouin scattering,Brillouin frequency shift,Optical fiber,Brillouin reflectometer,strain
更新于2025-09-16 10:30:52
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Broadband Laser Doppler Frequency Shift Emulator for Satellite Laser Communication
摘要： A novel emulator of laser Doppler frequency shift (DFS) for satellite laser communication based on microwave photonics technology is proposed and experimentally demonstrated. In order to overcome the bottleneck that the optical frequency shift signal with a wide frequency offset from near zero can hardly be obtained using traditional electro-optic or acousto-optic frequency shifting, the frequency of laser signal is first moved to a lower/higher fixed frequency and then shifted back to a higher/lower tunable frequency. The signal after cascaded frequency shifting in the opposite direction is equivalent to the original laser signal with DFS. In the experiment, the value and direction of DFS correspond to the magnitude and sign of the difference between the two frequency shifts. The DFS from -14GHz to +14GHz with a varying rate of 323MHz/s is accurately implemented. In addition, the side mode suppression ratio (SMSR) of laser signals with DFS are all over 52.3dB. The proposed scheme is significant to evaluate and test the DFS compensation capability of the satellite laser communication terminal.
关键词： Doppler Frequency Shift,Satellite laser communication,Electro-optic cascaded frequency shifting
更新于2025-09-12 10:27:22
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Selection of spectrum model in estimation of Brillouin frequency shift for distributed optical fiber sensor
摘要： To improve real-time performance in distributed optical ?ber sensor, the in?uence of Brillouin spectrum models on performance in estimation of Brillouin frequency shift (BFS) is systematically investigated. First, the related Brillouin spectrum models, objective functions, optimization algorithms and convergence criterion in estimation of BFS are introduced. The BFS estimation algorithms based on the Lorentzian, Gaussian, pseudo-Voigt and Voigt models are written in MATLAB. The algorithms are used to estimate BFS for numerically generated Brillouin spectra with di?erent values of SNR (Signal to Noise Ratio) and measured Brillouin spectra with di?erent values of pulse width and average time. The results reveal that regardless of the simpli?ed Lorentzian and Gaussian models or more accurate pseudo-Voigt and Voigt model-based algorithms used, the estimated BFS between di?erent algorithms is quite similar. However, the ?tting error of the simpli?ed model-based algorithms is larger than that of the more accurate model-based algorithms especially for the cases with high value of SNR. The computational burden of the former is less than that of the latter. The Voigt model-based algorithm requires the most computational e?ort. If the nonlinear least-square ?t method is used, the selection of spectrum model has no big in?uence on the accuracy in the estimated BFS. Therefore, the algorithm based on simpli?ed Lorentzian and Gaussian models should be selected in BFS estimation. Thus, not only high accuracy in BFS estimation is ensured, but also the computation time can, at best, decrease to one-tenth of the maximum value.
关键词： Spectrum model,Accuracy,Computation time,Brillouin frequency shift,Distributed optical ?ber sensing
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - All-Fiber System at 1750 nm Delivering 35 fs 230 kW Peak Power Pulses
摘要： Ultra-short (<70 fs) pulses in the short-wavelength infrared (>1.55 μm) are very attractive for many applications such as three-photon microscopy1, frequency metrology2, or high harmonic generation3. Solitonic self-compression is an attractive effect for this purpose as compression to sub-50 fs pulses can be achieved without the need for external compressing optics, directly out of an optical fiber. Self-compression at high energy was demonstrated around 2 μm in all-solid4 or gas-filled5 hollow-core-PCFs. However, the latter demonstrations were restricted to Tm emission band in order to reach the soliton self-compression effect in low-nonlinearity media. In this communication, we present a compact monolithic all-fiber source of ultrashort (35 fs) pulses emitting outside conventional lasing bands, from 1.65 to 2 μm based on Raman-induced soliton self-frequency shift (SSFS) and soliton self-compression (SSC).
关键词： ultra-short pulses,soliton self-compression,Raman-induced soliton self-frequency shift,solitonic self-compression,short-wavelength infrared
更新于2025-09-11 14:15:04
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[IEEE 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Vladivostok (2018.10.3-2018.10.4)] 2018 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Spectral Modulation Technique Based on Frequency-Shift Keying for High-Speed Optical Fiber-Wireless Communication System
摘要： In this paper we present novel spectral modulation technique for high-speed hybrid telecommunication systems. This technique is based on frequency-shift keying of three wideband pulses with central frequency hopping in desired sub-terahertz frequency range. Mathematical and simulation models of optimal pulses based on hyperbolic secant square function shaped to get maximum of provided power are presented. For such modulation scheme we also developed symbol coding technique that provides bit rate incensement and gains into spectral efficiency and interception security of telecommunication system. Simulation results of spectral modulated signal propagation in radio-over-fiber links are presented and discussed. Finally we introduce preliminary results for system performance with expanded number of applied pulses and advanced symbol coding technique.
关键词： frequency-shift keying,spectral modulation,mm-waves,radio-over-fiber,pulse shaping,symbol coding
更新于2025-09-11 14:15:04
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A Novel CMUTs-based Resonant Biochemical Sensor Using Electrospinning Technology
摘要： A novel CMUTs-based resonant biochemical sensor was presented to detect SO2 with a sensitive polymer electrospinning technology. The electrospinning technology was proposed as an innovative functionalization method to fabricate nano reticular polymer fibers with the diameters of 50 nm~500 nm on the movable plates of the CMUTs. The surface topography of electrospun nanofibers and the impedance properties of functionalized CMUTs were characterized. The CMUTs-based resonant biochemical sensor was packaged to detect SO2 in the experiments. Its resonant frequency shifts varied against the variation of SO2 concentration. The influences of the mixed gas flow rate were also analyzed. These showed the proposed sensor had good volume sensitivity and frequency stability.
关键词： volume sensitivity,electrospinning technology,impedance characteristics,CMUTs-based resonant biochemical sensor,frequency shift
更新于2025-09-11 14:15:04
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Broadband tunable Raman soliton self-frequency shift to mid-infrared band in a highly birefringent microstructure fiber
摘要： Raman soliton self-frequency shifted to mid-infrared band (λ > 2 μm) has been achieved in an air-silica microstructure ?ber (MF). The MF used in our experiment has an elliptical core with diameters of 1.08 and 2.48 μm for fast and slow axis. Numerical simulation shows that each fundamental orthogonal polarization mode has two wide-spaced λZDW and the λZDW pairs located at 701/2110 nm and 755/2498 nm along the fast and slow axis, respectively. Using 810-nm Ti:sapphire femtosecond laser as pump, when the output power varies from 0.3 to 0.5 W, the furthest red-shift Raman solitons in both fast and slow axis shift from near-infrared band to mid-infrared band, reaching as far as 2030 and 2261 nm. Also, mid-infrared Raman solitons can always be generated for pump wavelength longer than 790 nm if output pump power reaches 0.5 W. Speci?cally, with pump power at 0.5 W, the mid-infrared soliton in slow axis shifts from 2001 to 2261 nm when the pump changes from 790 nm to 810 nm. This means only a 20 nm change of pump results in 260 nm tunability of a mid-infrared soliton.
关键词： microstructure ?ber,soliton self-frequency shift,Raman soliton,mid-infrared
更新于2025-09-10 09:29:36
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Analytical Solution of Direct and Inverse Problems in the Internal Gravity Waves Studies by the Doppler Frequency Shift Method
摘要： An analytical solution of direct and inverse problems arising in the study of the internal gravity waves (IGWs) dynamic via recording of the Doppler frequency shift, is presented. The direct problem is to determine the response of the Doppler shift to IGWs in the region of the radio wave reflection point; the inverse problem is the determination of IGW parameters from data on the Doppler frequency shift. Solutions were obtained in an approximation of the isothermal ionosphere for the heights of the F-region. They are presented in a form convenient for their practical use and can have a wide range of applications, including the detection of soliton-like wave structures in the F-region of the ionosphere.
关键词： inverse problem,ionosphere,direct problem,internal gravity waves,Doppler frequency shift
更新于2025-09-09 09:28:46
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Selective trapping of micro-particles on terahertz metamaterial with macro gesture manipulation
摘要： To improve the sensitivity of detecting micro-particles, we propose new designs of terahertz metamaterial devices. These devices use microstructures to support the metal layer of metamaterial and thus can trap micro-particles at sensitive positions. We present two methods of selectively trapping micro-particles on such devices. One is to trap the micro-particles at the openings of split-ring-resonators (SRR), and the other is to trap them inside the SRR. Both methods use simple thumb gestures to control the movement of micro-particles. The methods can capture particles over a large surface area with time efficiency and low cost. Single particle trapped at each trapping site was achievable; the trapping rate was 64% using the first method, and 71% using the second. As a result, the resonant frequency before and after the micro-particles were trapped shifted 23 GHz for the first method and 71 GHz for the second. This shows great improvement as compared to earlier report of 15% trapping rate and 10 GHz resonant frequency shift.
关键词： micro-particles,terahertz metamaterial,selective trapping,resonant frequency shift,macro gesture manipulation
更新于2025-09-04 15:30:14