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相位敏感光时域反射系统以其分布式光纤传感技术的优势在分布式水听、压裂微地震检测、自然灾害预警等低频监测领域具有极高的应用前景。文中对系统中脉冲斩波信号与频率调制信号时钟不同源的问题予以验证,并对其产生的影响进行理论分析;设计双路同步时钟源驱动产生脉冲斩波信号和频率调制信号,降低每个脉冲重复周期中频率调制信号的随机低频相位噪声,提高探测脉冲光的相位稳定性;采用时钟同源和时钟非同源两种方式对典型的基于外差相干检测的相位敏感光时域反射系统的声光调制器进行驱动,由信号发生器驱动缠有光纤的压电陶瓷,产生不同频段的扰动信号。实验结果表明:在同一测试条件下,前者在低频段的信噪比、相位解调质量、频率响应方面均优于后者,最小响应频率为0.1 Hz,相对提高两个数量级,降低了系统中低频噪声干扰。该方法易于实现,可与现有的低频性能优化方法或结构兼容,进一步提高系统低频响应性能。 相似文献
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For the first time, optical modulation is used to determine the intrinsic frequency response of a laser diode. It is shown that the shape of the measured frequency response agrees very well with the predicted intrinsic response of semiconductor laser. As anticipated, the measured frequency response lacks the frequency rolloff that occurs with direct RF current modulation. The resonant frequencies measured are shown to be proportional to the square root of the probe laser bias power and the damping rates are found to be linear in power, in agreement with expectations 相似文献
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Measurements have been carried out using 1.3-μm distributed-feedback laser diodes (DFB-LDs). The frequency difference of the LDs is continuously varied with temperature changes of a few degrees and the spectral linewidth of one of the LDs is narrowed by optical feedback using a grating. Wideband, highly sensitive measurement has been achieved for a p-i-n photodiode and a Ge avalanche photodiode from DC to 20 GHz. The result is compared with that of the pulse spectrum analysis (PSA) method. Although the finite pulsewidth in the PSA method causes roll-off in the frequency response, the optical heterodyne method has the advantage for very wideband frequency response measurement. The S /N ratio in the optical heterodyne method can be made as high (~40 dB) as that of the PSA method by narrowing the spectral linewidth of DFB-LDs 相似文献
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A quantum well (QW) in the simultaneous presence of a terahertz field polarized in the growth direction and an incident optical field near an excitonic resonance results in substantial frequency mixing between the terahertz and optical fields. In particular, a response at new frequencies given by the input optical frequency plus or minus multiples of the terahertz frequency occurs-the terahertz sidebands. In a symmetric QW, the dominant contribution to terahertz-sideband formation is the high-frequency modulation of the overlap integral of the relevant conduction- and valence-subband envelope functions that determine the strength of the interband dipole moment. terahertz-sideband generation is shown to be strongly enhanced in a high quality-factor optical microcavity. Numerical values of the reflected intensity into the first terahertz sideband normalized with respect to the reflected intensity at the fundamental as large as /spl sim/10% are estimated. This suggests that terahertz-sideband generation in semiconductor microcavities is a promising option worthy of exploration for wavelength conversion for wavelength-division multiplexing applications. 相似文献
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光外差法测量光探测器频率响应的系统校准 总被引:1,自引:0,他引:1
通过实验证明了光外差法测量光探测器频率响应特性的一种校准方法的有效性.首先根据光外差法的基本原理详细推导了光探测器频率响应的表达式.发现了激光器调谐过程中的输出不稳定性是影响光外差法测量光探测器频率响应特性结果准确性的主要原因.激光器的输出不稳定性主要表现在输出光的偏振方向、光功率以及光谱不稳定造成的拍频信号线宽变化.实验对两个3dB带宽分别为10GHz和50GHz的探测器进行测量,逐一比较了采用与没有采用相应校准方法的结果,验证了该校准方法的有效性. 相似文献
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窄线宽稳频激光是研制光学原子钟、引力波探测、 光学频率合成器以及低噪声微波源等研究的核心部分,由振动噪声引起的频率噪声已成为实 现具有更窄线宽、更高频率稳定度 激光的主要限制性因素。本文利用Ansys有限元分析的方法,通过优化参考腔的切割深度和 支撑位置以及ULE环的尺寸,使得腔镜在振动作用下保持平行同时腔镜各点均具有较低的振 动敏感度,避免了由于装配误差引起腔长变化的问题。在对光学参考腔几何尺寸优化设计后,对光学谐振腔不同频率处的振动敏感度进行测试及分析,结果表明在最佳支撑位置下空间三轴方向的振动敏感度均可被抑制至 10-10 g-1量级,实验结果和仿真结果相吻合。此方法为振动免 疫结构腔体的设计提供了一种思路,也为进一步实现具有更高频率稳定度、更窄线宽激光奠 定了基础。 相似文献
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Si基单片集成850nm光接收芯片研究 总被引:6,自引:4,他引:2
设计并制备了一种Si基单片集成850nm光接收芯片,包括"P+/N-EPI/BN+"结构的光电探测器(PD)、跨阻前置放大电路及其后续处理电路。分析了PD的结构,并对其光谱响应及频率响应进行模拟,在2.0V偏压下,PD在850nm的响应度为0.131A/W,截止频率为400 MHz。采用0.5μm BCD(bipolar、CMOS和DMOS)工艺流片,光接收芯片面积约为900μm×1 100μm。测试结果表明,PD暗电流为pA量级,响应度为0.12A/W。光接收芯片在155 Mb/s速率及误码率(BER)小于10-9情况下,灵敏度为-12.0dBm;在622 Mb/s速率及BER小于10-9情况下,灵敏度为-10.0dBm,并能得到清晰的眼图。将该光接收芯片封装后接入光接收模块,进行点对点光互联实验,获得很好的光信号通路。 相似文献
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A theoretical analysis is provided to evaluate the performance of optical frequency division multiplexed systems taking into considerations the combined effect of receiver noise, laser phase noise and nonuniform FM response characteristic of a practical DFB laser. To overcome the effect of nonuniform frequency modulation characteristic of semiconductor lasers, two different linecoding schemes are used for the laser driving signal. The crosstalk penalty due to the combined effect of nonuniform FM response and phase noise of lasers is evaluated. The improvement in receiver sensitivity due to optical preamplifier is also estimated. The computed results show that the performance of the system is highly degraded due to the effect of laser nonuniform fm response and can be reduced substantially by using linecoding. Further, there is considerable improvement in receiver sensitivity due to the use of an optical preamplifier in the absence of phase noise. In the presence of phase noise there is a reduction in receiver sensitivity 相似文献
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利用传输矩阵法,研究复介质光量子阱光传输特性的增益效应机制,结果表明复介质对光量子阱内部局域电场和分立共振透射峰的透射率均具有增益放大作用:复介质光量子阱与实介质光量子阱一样,内部也存在很强的局域电场以及透射谱中也出现分立的共振透射峰,但复介质光量子阱的内部局域电场和分立共振透射峰会出现增益放大现象。在光量子阱的组成介质A中掺入具有增益效应的激活性杂质时,光量子阱的内部局域电场首先随着激活性杂质含量的增加而放大增强,但增益放大到极大值后又开始衰减下降,而且不同入射光波长,光量子阱内部局域电场增益放大的极大值及其对应的激活杂质含量不同,其中对处于短波方向的光入射时内部局域电场对激活杂质含量的响应最灵敏最高,而且内部局域电场增益放大的极大值最大,对处于长波方向的光入射时内部局域电场对激活杂质含量的响应灵敏度最低,内部局域电场增益放大的极大值最小。复介质光量子阱光传输特性的增益效应机制,对新型光学滤波器、光学放大器和激光器等光学器件的理论研究与实际设计,以及光量子阱光传输特性的内在机制研究等,均具有积极的指导意义。 相似文献
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A novel method is demonstrated to tunably compensate dispersion effect in phase modulated radio over fiber (RoF) links using an optical carrier Brillouin processing technique,which is based on stimulated Brillouin scattering (SBS) to control the phase shift of optical carrier in the modulated iightwave signal.Since this phase shift can be dynamically tuned,frequency response can be tunably improved.Both simulation and experimental results show that a uniform frequency response ranging from 1-12 GHz with a fluctuation of less than --1 dB can be obtained by an optimal phase shift on the optical carrier. 相似文献
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A general design algorithm is presented for infinite impulse response (IIR) bandpass and arbitrary magnitude response filters that use optical all-pass filters as building blocks. Examples are given for an IIR multichannel frequency selector, an amplifier gain equalizer, a linear square-magnitude response, and a multi-level response. Major advantages are the efficiency of the IIR filter compared to finite impulse response (FIR) filters, the simplicity of the optical architecture, and its tolerance for loss. A reduced set of unique operating states is discussed for implementing a reconfigurable multichannel selection filter 相似文献
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Bhattacharya D. Erlig H. Ali M.E. Shamino Wang Fetterman H.R. Lai R. Streit D.C. 《Quantum Electronics, IEEE Journal of》1997,33(9):1507-1516
We present measurements on the optical frequency response of epitaxial lift-off (ELO) 1.0-μm InP high-electron mobility transistors (HEMTs) to 140 GHz using electrooptic sampling and heterodyne techniques. Our picosecond sampling measurements established that the lift-off devices exhibited substantial optical response to 140 GHz. Heterodyne measurements made at 60 and 94 GHz later confirmed these findings. A novel three wave mixing technique was used to extend the heterodyne bandwidth to 130 GHz. In these experiments, millimeter waves were generated in our optically driven HEMT's and launched into waveguides. These lift off devices can be major additions to future millimeter wave integrated optoelectronic systems either as high frequency optical detectors or as optically driven tunable millimeter wave sources 相似文献
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Automatic frequency control (AFC) in an injection locked or resonant type amplifier in an AlGaAs semiconductor laser was achieved through using the terminal voltage change induced by light injection. Signal-to-noise ratio in the control signal of 10 dB was obtained when the input optical power was -47 dBm and the optical gain Was 51 dB. The AFC was maintained for 3 h with an 0.3-percent output power fluctuation for 2°C ambient temperature change and 65-MHz frequency stability. Step response showed that the system response time was 1.5 s. Sensitivity to input optical power deteriorates at -49 dBm, with a 53-dB locking gain, because of frequency deviation caused by temperature modulation. The second derivative of the induced voltage and it's relation to the optical frequency is constant at5 times 10^{-10} [V/(MHz)2] for all input power levels in a buried-heterostructure (BH)-AlGaAs laser. Terminal voltage change induced by light injection is calculated by simple rate equations with a Gaussian-Halperin-Lax (GHL) bandtail model. Good agreement with experimental results was seen. 相似文献
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Takahata K. Kasaya K. Yasaka H. Kondo Y. Ikeda M. 《Quantum Electronics, IEEE Journal of》1994,30(5):1219-1226
A novel optical frequency conversion device that successfully demonstrates optical frequency conversion and unidirectional transmission of optical signals has been designed and fabricated. The device is composed of a gain region and saturable absorber region with monolithically integrated distributed Bragg reflector (DBR) mirrors with different coupling coefficients. The device structure is optimized to achieve three functions: 1) unidirectional light output, 2) converted-light wavelength tuning, and 3) optically triggered optical frequency conversion. The output power of converted light from the light input-end facet of the device is 30 dB smaller than that from the output-end facet, and the converted light wavelength can be scanned over 4 nm without a bias current to the input-end DBR region, and it is widened to 7.8 nm by injecting current to that region. The device emits converted light only when light input is injected and optical signals are unidirectionally transmitted, and its response frequency is estimated to be 0.8 GHz 相似文献
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For CPFSK lightwave systems with noncoherent detection using a Fabry-Perot filter, the optimum frequency deviation is determined experimentally when the EFM response is nonuniform, as for a single-electrode DFB laser, and the filter bandwidth is narrow. Owing to the passband response of the optical filter, the optimum frequency deviation is considerably larger than that for a heterodyne receiver.<> 相似文献
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M. Homar C.R. Mirasso I. Esquivias M. San Miguel 《Photonics Technology Letters, IEEE》1996,8(7):861-863
We theoretically investigate the influence of optical feedback on the modulation response of quantum-well lasers. Controlled weak optical feedback is shown to be useful to improve the high frequency performance, compensating the limitations imposed by carrier-transport effects. 相似文献
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A supervisory (SV) signal transmission scheme for long haul optical amplifier systems is described. The scheme is based on subcarrier overmodulation of the line signal and features simple configuration; due to the use of EDFA gain modulation, no additive optical components are required in a submarine repeater to transmit a response signal. This paper discusses the subcarrier modulation index and frequency used for the SV signaling, the most significant design parameters. The dependence of the signal-to-noise ratio (SNR) on the modulation index in SV signal transmission is analyzed to clarify the modulation index value required for reliable SV signaling. In addition, the line signal impairment caused by subcarrier overmodulation is also analyzed to show the system's in-service feasibility. The subcarrier frequencies used for command and response signal transmission are discussed from the experimental results on the frequency response of an optical amplifier system and EDFA gain modulation efficiency 相似文献