基于注入半导体激光器的微波副载波相位调制信号产生

光载无线技术是解决终端超宽带无线通信的重要方法,光信号与微波/毫米波信号的融合处理技术在光-无线的数据格式转换中至关重要.提出了一种基于相位调制信号光注入Fabry-Perot型半导体激光器实现微波副载波相位调制信号产生的方法.光学注入半导体激光器的输出光场会产生一周期(P1)振荡效应, P1振荡产生的边带实现了相位调制信号光的调制分量的放大,被放大的调制分量与注入光载波在激光器腔内拍频形成微波副载波.注入光相位的变化导致新产生的微波副载波相位变化, 实现了注入信号光相位信息转化为微波副载波相位信息.本系统完成1.3 Gb/s, 2.7 Gb/s, 2 Gb/s光相位调制信号到微波副载波相位调制信号的转换,并测量了微波的单边带相位噪声. 通过光电转换和电域混频将还原出的光基带信号与原信号进行逻辑对比,证明了数据信息转换的正确性.     

An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer

Recently, a Rydberg atom-based mixer was developed to measure the phase of a radio frequency (RF) field. The phase of the signal RF (SIG RF) field is down-converted directly to the phase of a beat signal created by the presence of a local RF (LO RF) field. In this study, we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation (AM) of the LO RF field; that is, the phase of the SIG RF field is related to both the amplitude and phase of the beat signal. When the AM frequency of the LO RF field is the same as the frequency of the beat signal, the beat signal will further interfere with the AM of the LO RF field inside the atom, and then the amplitude of the beat signal is related to the phase of the SIG RF field. The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 to π/2 when the phase of the AM is set with a difference π/4 from the phase of the LO RF field. The minimum phase resolution can be as small as 0.6° by optimizing the experimental conditions according to a simple theoretical model. This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.     

基于相位调制-解调的光纤激光相位噪声检测方法研究

在主动相位控制相干合成中,常用的光纤激光主动相位控制方法主要有外差法、多抖动法和随机并行梯度下降算法等. 基于多抖动法和外差法的原理,提出了一种新型的基于相位调制-解调的相位检测与控制方法. 该方法利用周期信号对参考光进行相位调制,将调制后的参考光与待检测信号光进行相干检测,通过对相干光强信号和相位调制信号的融合处理,实现相位噪声的检测和控制. 对该方法进行了数值模拟和实验研究. 实验结果表明,对于频率为2 kHz,噪声范围为[0,2π)的正弦噪声,相位检测精度优于λ/50,控制精度可达 关键词： 光纤激光 相干合成 相位噪声检测 调制-解调     

克服光纤Mach-Zehnder干涉仪信号衰落的新方法及分析

为了克服光纤Mach-Zehnder干涉仪易受环境因素影响而引起偏置相位漂移从而导致输出信号衰落(波动)的问题,提出一种新的简单方法,即:将干涉仪输出信号分为直流和交流两个分量,通过直流分量的大小来计算交流信号的补偿因子,以达到克服交流信号衰落、稳定检测传感信号的目的在小信号测量情况下,该方法在很大范围内能有效抑制随机温度涨落等因素引起的信号衰落的问题文中对补偿方法的误差和局限性也做了分析和讨论.     

数字BPM时钟锁相电路的设计与实现

为实现数字BPM时钟系统的锁相,设计了一种基于锁相环同步原理的低抖动、低相位噪声的时钟同步系统。根据锁相环电路工作原理,对数字BPM时钟同步系统的硬件及固件程序进行了设计,实现了外部输入时钟信号与系统内部产生的主工作时钟信号的锁相,并且时钟信号输出的频率及相位均可调整以满足后端ADC采样的要求。测试结果表明,设计可以完成对一定频率范围内变化的外部输入时钟信号的锁相,输出时钟信号抖动满足束流实验要求,为数字BPM后续算法研究提供了基础。     

基于微波相位补偿的56 km高精度光纤微波频率传递

报道了实验室内56 km光纤微波频率传递的实验研究,在56 km的传递距离上实现了1.8×10-15/s,4×10-18/104s的传递稳定度.系统通过环回法比较往返传递的微波信号相位获得链路上的相位扰动量,并实时控制本地发射端的微波发射信号相位实现预补偿.在环回往返传递的不同方向上,系统方案采用不同频率的微波调制信号...     

A Device for Phase Shift Measurement in an Advanced Phase Doppler Velocimeter

Construction and performance of a printed circuit board is described that is built for phase measurement in a state-of-the-art phase Doppler system. Special requirements in treating phase Doppler signals are highlighted and shown to be met satisfactorily by an innovative electronic design that involves signal burst detection, multi-bit sampling, frequency-band narrowing, and phase signal validation based on integrated amplitude and waveform recognition. Performance of the device is measured in terms of phase accuracy for various signal-to-noise ratios, signal frequencies and operating temperatures. The present device is also compared with some alternative techniques for phase measurement.     

Differential phase measurements in low-coherence interferometry without 2pi ambiguity

Quantitative phase measurements by low-coherence interferometry and optical coherence tomography are restricted by the well-known 2pi ambiguity to path-length differences smaller than lambda/2 . We present a method that overcomes this ambiguity. Introducing a slight dispersion imbalance between reference and sample arms of the interferometer causes the short and long wavelengths of the source spectrum to separate within the interferometric signal. This causes the phase slope to vary within the signal. The phase-difference function between two adjacent sample beam components is calculated by subtraction of their phase functions obtained from phase-sensitive interferometric signal recording. Because of the dispersive effect, the phase difference varies across the interferometric signal. The slope of that phase difference is proportional to the optical path difference, without 2pi ambiguity.     

基于独热码有限状态机的斐索干涉解调相位补偿方法

针对相位调制型超弱光纤光栅水听器阵列解调过程中发生的相位翻转现象,提出了一种基于独热码编码的有限状态机相位补偿方法,用来在现场可编程逻辑门阵列中对翻转信号进行实时修正.将解调信号相位及其补偿条件设计在独热码编码的有限状态机中,通过状态机内部状态的即时转移,实现高时钟速率下光纤干涉系统解调信号的相位补偿.对多种相位补偿方式在功能仿真和实验测试中的功耗、占用资源及时序等进行对比分析,结果表明基于独热码状态机的相位补偿方法,不仅可以正确地解决相位翻转问题,保证信号的完整性,同时还可以增加信号解调动态范围,使系统的逻辑延迟降低6%,在水声光纤传感解调系统的高吞吐率和高时钟频率应用环境下具有一定优势.     

Effect of signal phase and masker separation on two-tone masking

The detectability of a sinusoid masked by two sinusoids was studied as a function of signal phase and the frequency separation between the two maskers. The signal frequency fs was equal to the arithmetic mean of the two masker frequencies, fl and fh, where fl less than fh. Signal frequencies of 1 and 4 kHz, eight signal phases, and 12 values of r = (fh-fl)/fs from 0.01-1.0 were used. The data could be divided into three regions. For large masker separations, r greater than 0.4, no consistent effects of signal phase were observed. For r less than 0.4, an effect of signal phase was evident at both signal frequencies. However, the effect of signal phase was different for the two regions 0.03 less than r less than 0.4 and r less than 0.03. For moderate masker separations, 0.03 less than r less than 0.4, masked thresholds were lowest at phases of 0 degrees and 180 degrees and highest at phases of 90 degrees and 270 degrees. For small masker separations, r less than 0.03, masked threshold was highest at 0 degree and the effect of signal phase depended on signal frequency. The different form of the phase effect for these three regions is discussed in terms of the use of different cues, arising from temporal resolution, spectral filtering, combination tones, and envelope spectra.     

基于光子晶体光纤的相位再生器的设计及优化

采用光子晶体光纤构成一个Sagnac环,在锁相本地振荡抽运源的驱动下,形成一个相位再生器,实现对差分相移键控调制信号的相位和幅度再生.理论推导了入射光信号经过相位再生器后的光场分布,讨论了不同入射信号光功率下,抽运光与信号光的相位差以及光子晶体光纤长度对信号功率增益的影响,给出了相位再生器的最优参数,数值模拟了信号再生前后的相位分布、强度分布及误码率,取得了很好的再生效果. 关键词： 光通信 相位再生 光子晶体 差分相移键控信号     

Randomness control of vehicular motion through a sequence of traffic signals at irregular intervals

We study the regularization of irregular motion of a vehicle moving through the sequence of traffic signals with a disordered configuration. Each traffic signal is controlled by both cycle time and phase shift. The cycle time is the same for all signals, while the phase shift varies from signal to signal by synchronizing with intervals between a signal and the next signal. The nonlinear dynamic model of the vehicular motion is presented by the stochastic nonlinear map. The vehicle exhibits the very complex behavior with varying both cycle time and strength of irregular intervals. The irregular motion induced by the disordered configuration is regularized by adjusting the phase shift within the regularization regions.     

Binaural masking experiments using noise maskers with frequency-dependent interaural phase differences. II: Influence of frequency and interaural-phase uncertainty

This study investigates whether binaural signal detection is improved by the listener's previous knowledge about the interaural phase relations of masker and test signal. Binaural masked thresholds were measured for a 500-ms dichotic noise masker that had an interaural phase difference of 0 below 500 Hz and of pi above 500 Hz. The thresholds for two difference 20-ms test signals were determined within the same measurement using an interleaved adaptive 3-interval forced-choice (3IFC) procedure. In each 3IFC trial, both signals could occur with equal probability (uncertainty). The two signals differed in frequency and interaural phase in such a way that one signal always had a frequency above the masker edge frequency (500 Hz) and no interaural phase difference (So), whereas the other signal frequency was below 500 Hz and the interaural phase difference was pi (S pi). The frequencies of a signal pair remained fixed during the whole 3IFC track. These two signals thus lead to two different binaural conditions, i.e., NoS pi for the low-frequency signal and N pi So for the high-frequency signal. For comparison, binaural masked thresholds were measured with the same masker for fixed signal frequency and phase. The binaural masking level differences (BMLDs) resulting from the two experimental conditions show no significant difference. This indicates that the binaural system is able to apply different internal transformations or processing strategies simultaneously in different critical bands and even within the same critical band.     

A low noise,high fidelity cross phase modulation in multi-level atomic medium

We develop a hybrid scheme of cross phase modulation based on electromagnetically induced transparency (EIT) and active Raman gain (ARG) in a multi-level atomic medium. The cross phase modulation, with low loss and without noise, is demonstrated in a room-temperature ⁸⁵Rb vapor. We show that a π radian nonlinear Kerr phase shift of the signal light relative to a reference light is observed when the signal light is modulated by the phase control field with the low light intensity. We also show that the linear and the third-order absorption can be eliminated via the Raman gain, and the phase noise of the signal light can be ignored when the phase control light is applied in this hybrid scheme.     

Phase noise generation in an amplitude limiter using saturation of a fiber-optic parametric amplifier

Generation of phase noise in an amplitude limiter using saturation of a fiber-optic parametric amplifier is analyzed. The analysis is based on the coupled differential equations for the amplitudes and phases of pump, signal, and idler involved in the four-wave mixing interaction. The equations are linearized about small fluctuations at operation points and are solved, which results in relations between the input and output phase and amplitude noise. These relations are used in deriving expressions of amplitude signal-to-noise ratio (SNR) and variance of phase noise of the output signal in terms of SNRs of input signal and pump. It is shown that optimum pump power exists for minimum output phase noise in the output signal.     

The study of third harmonic demodulation in phase modulation optical heterodyne technique using optical resonator

With the technique of phase modulation optical heterodyne(PMOH), we detected the beat-frequency signal of the reflected wave from a F-P cavity. The frequency of the beat signal was three times of that of the modulation electric field, when the 3rd harmonic of the modulation electric field was used as the phase reference signal. The line shapes of the signal match those of the theoretical calculations, and the dispersion signal has good frequency-discrimination characteristic.     

Two-dimensional phase retrieval using a window function

Two-dimensional phase retrieval by use of a window function is considered. First the uniqueness and the reconstruction of a two-dimensional signal from the Fourier intensities of the three signals, an original signal, the signal windowed by a window w(m, n) , and the signal windowed by its complementary window w(c)(m, n) = 1 - w(m, n) , are addressed. Then phase retrieval without a complementary window is considered. Conditions under which a signal can be uniquely specified from the Fourier intensities of the original signal and the windowed signal by w(m, n) are developed, and a reconstruction algorithm is presented.     

Equalization-enhanced phase noise induced timing jitter

In electronic digital signal processing based optical communication systems, digital equalization for chromatic dispersion interacts with local oscillator phase noise to produce equalization-enhanced phase noise (EEPN). In addition to both phase and intensity noises, EEPN also induces timing jitter to the equalized signal. For a 100?Gbit/s quadrature-phase-shift keying signal with laser linewidth of 300?kHz, the timing jitter is up to 20% of the symbol interval for a transmission distance of 1500?km.     

Correction to: Generation of amplitude- and phase-modulated signal beam with a phase-only spatial light modulator and its detection by the transport of intensity equation method for holographic data storage

This study evaluates a novel holographic data storage (HDS) that uses a phase-only spatial light modulator (SLM) for the multilevel complex amplitude modulation of a signal beam and the transport of intensity equation (TIE) method to detect the signal beam without interferometry, to increase the capacity of the HDS, simplifying its optical system, and improving the stability of the signal beam modulation and detection. Both the amplitude and phase of the signal beam were modulated by a computer-generated hologram displayed in a phase-only SLM, a 4-f optical system, and a pinhole placed in the Fourier plane. The complex amplitude-modulated signal beam generated by this scheme does not always perfectly match the target complex amplitude, and deviations from the amplitude and phase of the target complex amplitude may exist. It is unclear whether the TIE method, which is sensitive to the state of the beam intensity and the phase distributions to be detected (such as zero-intensity points and phase discontinuities), can accurately detect a signal beam whose complex amplitude is modulated by the modulation scheme with a phase-only SLM. Here, we demonstrate via numerical simulations and experiments that several methods of complex amplitude generation using a phase-only SLM can achieve multilevel modulation of the amplitude and phase of a signal beam and are suitable for detection by the TIE method in HDS.

     

用于PZT调制干涉仪的外触发式差动数字鉴相技术

基于相位测量的外差干涉系统以其信号处理方面的优势在光学计量领域得到了广泛的应用。介绍了采用机械调制方法的差动单频干涉系统的干涉信号小数级次的相位测量实现方法。针对机械调制干涉系统的信号有相位跃变点且周期不均匀的特点 ,提出了利用外触发信号对干涉信号进行整周期截取而后再鉴相的方法。研制了基于 FPGA的外触发式差动数字鉴相系统。实验测试表明 ,该鉴相系统在信号频率为 30 0 Hz～ 10 k Hz范围内达到的指标为 :示值稳定性优于± 0 .0 15°,极限偏差小于± 0 .0 7°