- 标题
- 摘要
- 关键词
- 实验方案
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Reduction of the chromatic dispersion and chirping effects by using an injection-locked and directly intensity-modulated Fabry–Pérot laser in point-to-point optical access networks
摘要： We present recent improvements achieved for two important transmission parameters—dispersion, induced by the optical fiber, and the chirp parameter of the laser source—in a directly modulated system based on an injection-locked and directly modulated Fabry–Pérot laser diode for high-speed optical access networks with a point-to-point topology. Measurements in the 20-GHz range of the frequency response for distances up to 35 km are conducted by carefully adjusting the optical power and frequency detuning of the distributed master laser in the central office, thereby overcoming the problem of chromatic dispersion in high-speed optical access. Moreover, the enhancements make it possible to increase the transmission distance when a 1550-nm Fabry–Pérot laser is used as the light source in the central office of a point-to-point optical access network by distributing the seed light into numerous downstream lasers. This improvement to the injection-locked Fabry–Pérot laser is expected to extend the length of already-built, fiber-to-the-home, point-to-point networks with a simple upgrade in the central office without prejudicing the terminal equipment.
关键词： Semiconductor lasers,Injection locking,Frequency response,Modulation
更新于2025-09-11 14:15:04
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Polarimetric Fiber Vibration Sensor Based on Polarization-Diversified Loop Using Short Polarization-Maintaining Photonic Crystal Fiber
摘要： In this paper, we demonstrated a polarimetric fiber vibration sensor based on a polarization-diversified loop (PDL) with short polarization-maintaining photonic crystal fiber (PM-PCF) as a sensor head and investigated the dependence of its frequency response on the sensing fiber length. The fabricated PM-PCF vibration sensor is composed of a polarization beam splitter for forming the PDL, PM-PCF as a sensor head, and two wave plates such as a quarter-wave plate and a half-wave plate. A laser diode and a photodetector were also utilized for intensity-based vibration measurement. In particular, two kinds of PM-PCF segments with fiber lengths of ～6 and ～10 cm were employed to explore the effect of the sensor head length on the sensor frequency response. The frequency response was examined over 1–3000 Hz using a piezoelectric transducer that can apply single-frequency vibration to the sensor head. Every measured frequency response showed a resonance peak at each sensor head length, and cut-off frequencies were measured as ～1240 and ～794 Hz for PM-PCF lengths of ～6 and ～10 cm, respectively. That is, a higher cut-off frequency was obtained in a shorter sensor head length. Moreover, it was observed that the sensor head length dependence of the frequency response was maximized in a frequency range from 1000 to 2400 Hz and faded away beyond 2400 Hz. From the measurement results, it is concluded that the short sensor head can provide higher normalized sensitivity, i.e., better signal to noise ratio, at frequencies higher than the resonance frequency, let alone convenience of installation and in sensitiveness to external perturbations in a PDL-based PM-PCF vibration sensor. The phase shift per unit strain and the minimum detectable strain perturbation, regarded as sensitivity and resolution, were measured as ～0.377 mrad/με and ～0.16 nε/Hz1/2 at 2000 Hz for ～6-cm-long PM-PCF, respectively.
关键词： Polarization-Maintaining Photonic Crystal Fiber,Polarization-Diversified Loop,Frequency Response,Optical Fiber Vibration Sensor
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Keysight 3458A Frequency Response Model Identification
摘要： This paper describes a measurement and a model parameter identi?cation of Keysight 3458A frequency response in sampling mode. When modeling the frequency response with aperture time sinc roll-off, single pole low pass ?lter and linear input capacitance dissipation factor roll-off, a better than 20 μV/V linearity and ac voltage accuracy can be achieved in the audio frequency band on 1 V range.
关键词： frequency response,sampling,linearity,Measurement
更新于2025-09-10 09:29:36
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Frequency response study of surface acoustic wave devices with SiO <i> <sub/>x</sub></i> N <i> <sub/>y</sub></i> film using LiTaO <sub/>3</sub> substrate
摘要： In an attempt to suppress the frequency variation of a surface acoustic wave device caused by dielectric ?lm deposition on an interdigital transducer (IDT) electrode, we fabricated a one-port resonator and examined the correlation with frequency response and refractive index when a SiOxNy ?lm is deposited. Our data showed that the resonator frequency changes as the refractive index of the SiOxNy ?lm changes. We also found that the frequency drift caused by the SiOxNy deposition can be suppressed if the refractive index is kept in a certain range. Then, we performed a ?nite element method spectral domain analysis to calculate frequency response using the Young’s modulus obtained in this experiment. The calculated frequency response indicated that the refractive index of the SiOxNy ?lm needs to be altered in accordance with the IDT electrode thickness. We suggest that one of the e?ective ways of controlling the frequency response is to manage the refractive index of SiOxNy.
关键词： SiOxNy ?lm,frequency response,refractive index,IDT electrode,surface acoustic wave device
更新于2025-09-10 09:29:36
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Frequency response of the leap motion controller and its suitability for measuring tremor
摘要： Although tremor is one of the most common movement disorders, it is evaluated using relatively coarse clinical scales. We propose to measure tremor in clinical settings using the Leap Motion Controller (LMC), which is a markerless motion capture sensor that has a low cost, zero set-up time, and dynamic accuracy of 1.2 mm. However, the frequency response of the LMC has not been characterized, so its ability to track oscillations such as tremor is unknown. To characterize the frequency response of the LMC, we measured the position of a mannequin hand simultaneously with the LMC and a high-resolution encoder while the mannequin hand oscillated at various combinations of frequency (1–15 Hz) and amplitudes (0.01–30 mm). We calculated the magnitude ratio and phase shift of the LMC and found the bandwidth of the LMC to range from 0–3 Hz to 0–5 Hz for tremor amplitudes greater than the dynamic accuracy. This bandwidth is too small to accurately measure most tremors. However, we developed an inverse ?lter to estimate the actual tremor amplitude and phase despite the limited bandwidth. Over the combinations of frequency and amplitude mentioned above, the inverse ?lter estimated the actual tremor amplitude and phase with errors of 3% and 2%, respectively.
关键词： Markerless motion capture,Frequency response,Tremor,Leap motion controller
更新于2025-09-09 09:28:46
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Competing optical instruments for the estimation of Full Field FRFs
摘要： Thanks to the progress of optical measurement systems, known to use non-contact transducers (with their own peculiarities, application domains and drawbacks), nowadays addressing complex testing problems, especially direct dynamic measurements and modal analyses on lightweight structural components, is becoming even more common than in the recent past. Furthermore, obtaining vibration patterns with optical gears, in broad frequency bands with high spatial resolution, is easier than before, for the advantage of many advanced applications in vibration engineering, testing and product development.
关键词： Full Field Operative Deflection Shapes,Full Field Frequency Response Functions,Dynamic ESPI,Full field vibration measurements,Surface structural dynamics,Optical metrology,Hi-Speed DIC,SLDV
更新于2025-09-09 09:28:46
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Bandwidth-Enhanced PAM-4 Transmissions using Polarization Modulation and Direct Detection with a Tunable Frequency Range
摘要： We propose a polarization-modulation and direct-detection (PolM-DD) bandwidth-enhanced PAM-4 transmission system with a tunable frequency range and demonstrate, for the first time, its performance after transmissions through a standard single mode fiber (SSMF). By adjusting the polarization angle between one principal axis of the PolM and polarizer, the frequency notch, caused by the spectral dispersion inherent in SSMF, can be shifted to higher frequencies. As a consequence, the available 3-dB bandwidth at the baseband is much more enhanced than it would be in the traditional case of an intensity-modulation and direct-detection (IM-DD) system. Since the output of PolM modulation module are intensity modulated signals with a tunable chirp, the system is free of polarization-mode dispersion (PMD). From the analysis in this paper, we conclude that under ideal conditions, the PolM-DD system gains approximately 41.4% in bandwidth over its counterpart IM-DD system. The optimal polarization angle is independent of optical wavelengths and fiber distances, so it can be easily applied in wavelength-division-multiplexing (WDM) systems. In our experiment, 100-Gbps, 84-Gbps, 68-Gbps, 58-Gbps and 52-Gbps PAM-4 signals are successfully transmitted by our PolM-DD system over distances of 5-km, 10-km, 15-km, 21-km and 25-km SSMF, respectively, without dispersion compensation component or single sideband (SSB) modulation. The experimental results are consistent with our analysis and simulations results, and support more than 41% data rate gain compared to the IM-DD system, given comparable component bandwidths.
关键词： tunable frequency response,optical communication,Polarization modulator
更新于2025-09-09 09:28:46
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Inductive Power Transfer for T5 Fluorescent Lamp Lighting System
摘要： This study discusses the characteristics of the inductive power transfer (IPT) for T5 fluorescent lamps (FL) lighting system. The advantages of the IPT technology are electrical isolation and capability of operating in dirt environment. The transfer function and frequency response of the IPT for T5 FL lighting system are derived. The experimental results under varied air gap and load are discussed to evaluate the property of the IPT for T5 FL lighting system.
关键词： Frequency Response,Inductive Power Transfer,Fluorescent Lamp,Series-Parallel Resonant
更新于2025-09-04 15:30:14