高速光探测器频率响应的精确表征

提出一种新的基于分布布拉格反射可调激光器的光外差频率响应测试系统,并给出了准确有效的校准方法来消除输出光功率和拍频线宽的波动等引起的误差,从而可以精确表征高速光探测器的频率响应特性.通过对标准高速光探测器的测试和校准,得到的结果与制造商提供的数据表相当符合,证明了该测试方法的准确性和有效性.文中也研究了系统中可能会影响频响特性测量的其他因素,如光源的边模抑制比、波长调谐速度等.     

光外差法测量光探测器频率响应的系统校准

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.     

光探测器芯片的高频特性测量

为了克服用共面探针测量光探测器芯片的高频特性对电极结构的限制．提出了一种精确测量光探测器芯片的阻抗和频率响应的新方法。对于任意电极结构的探测器芯片，首先把芯片与测试夹具连接，通过一系列的校准和测量，可以得到夹具的S参数，进而利用微波理论扣除整个测试夹具的影响，得到探测器芯片的S参数，计算出光探测器的阻抗和频率响应特性。用该方法对P极和N极共面的光探测器芯片的阻抗和频率响应特性进行了测量，并与直接用微波探针测量的结果相比较，验证了该方法在50MHz～16GHz的频率范围内的正确性。     

流图法在光探测器芯片高频特性测量校准上的应用

在采用光调制法测量光探测器芯片高频响应特性的过程中,测试系统往往忽视光调制器响应、高频探针衰减以及端口间失配等误差中的一项或几项.为了降低校准不完善对结果造成的误差,文中提出了基于信号流图的系统校准分析方法,考虑了各种频响误差及端口间失配的影响,推导出校准公式.利用该法对一种光探测器的典型测试系统--基于LCA(lightwave component analyzer)的测试系统做了进一步校准分析,在130MHz～20GHz范围内,测量了一种新型光探测器的高频响应参数S21,结果表明经流图法校准的S21参数比仅使用原有校准算法有明显改善,证明了该方法的可行性.     

谐振腔增强型光探测器的高速响应性能研究

高速长波长光探测器是高速光纤通信系统和网络的关键器件，它要求光探测器具有宽的频率响应带宽和高量子效率。常用的PIN光探测器由于量子效率和高速性能均受到吸收层厚度的牵制，使得二者相互制约，成为一对矛盾。谐振腔增强型(RCE)光探测器为这一矛盾的解决提供了有效的方案。基于谐振腔增强型光探测器的实际设计和制作模型，分析了器件吸收层中的光场分布，并将其运用于载流子的连续方程，从理论上详细地分析了器件的高速响应特性，给出了计算结果。针对研制的高速长波长谐振腔增强型光探测器，进行了理论分析和实际器件测试的结果比较，得到了比较一致的结果。     

流图法在光探测器芯片高频特性测量校准上的应用

在采用光调制法测量光探测器芯片高频响应特性的过程中,测试系统往往忽视光调制器响应、高频探针衰减以及端口间失配等误差中的一项或几项.为了降低校准不完善对结果造成的误差,文中提出了基于信号流图的系统校准分析方法,考虑了各种频响误差及端口间失配的影响,推导出校准公式.利用该法对一种光探测器的典型测试系统--基于LCA(lightwave component analyzer)的测试系统做了进一步校准分析,在130MHz～20GHz范围内,测量了一种新型光探测器的高频响应参数S21,结果表明经流图法校准的S21参数比仅使用原有校准算法有明显改善,证明了该方法的可行性.     

电吸收调制激光器集成芯片的高频测试

提出了一种精确测试电吸收调制激光器(EML)集成芯片高频特性的方法。待测芯片制作在带有微带线的热沉上,同时采用光探测器作为光电转换器,二者构成待测双口网络。被测双口网络的一端是共面线,使用微波探针作为测试夹具加载信号,另一端是同轴线,两个测试端口不同,不能采用简单的同轴校准方法校准待测系统。测试过程中采用扩展的开路-短路-负载(OSL)误差校准技术对集成器件的测试夹具微波探针进行校准,扣除了测试中使用的微波探针对集成光源高频特性的影响,同时采用光外差的方法扣除了高速光探测器的频率响应对结果的影响,得到集成光源散射参数的精确测试结果。     

一种渐变掺杂型pin光探测器的高速响应性能研究

高速光探测器是高速光纤通信系统和网络中的关键器件,它要求光探测器具有宽的频率响应带宽和高量子效率。垂直入光型pin光探测器的高速性能和量子效率均受到吸收层厚度的限制。为了改善其高速性能,采用InGaAsP材料作为吸收层以及限制层渐变掺杂的方法,对垂直入光型pin光探测器的高速响应性能进行了理论研究和仿真,结果表明,高速响应达到了40GHz。与不采用渐变掺杂浓度的同种结构光探测器相比,高速响应性能显著提高。     

扫频法精确测量高速光调制器频率响应

同微波网络一样,可以用S参数来精确描述光电子器件的性能.根据微波网络的S参数,详细推导了光电子器件的S参数.搭建了40 GHz高速测试系统,利用矢量网络分析仪(带宽40 GHz)和作为参考的标准高速光探测器(带宽45 GHz),测量了宽带光强度调制器(实测带宽35 GHz)的频率响应.理论上,通过S参数和T参数的互相转换,扣除了微波放大器对测试结果的影响.在120 MHz～35 GHz范围内,测得的结果与出厂数据取得了很好的一致性.文中通过合理的简化,得到了光调制器频率响应的简明表达式,从而降低了数据处理的复杂度.     

一种改进光探测器高速性能的新方法

研究了一种在光探测器的结构设计中加入平面螺旋电感从而提高光探测器高速性能的新方法。对影响探测器频率响应的因素进行分析,结果表明,增加电感值可以减小结电容对高速性能的限制,仿真结果也得到同样的结论。根据理论分析结果制作出探测器并进行测量,测量数据显示,未加电感的光探测器高速性能只能达到2GHz,而加电感的光探测器高速性能最大,可以达到5GHz,证明了电感值的增加可以明显提高器件的高速性能,得到了与理论分析一致的结果。     

Small-signal response of 1.3-/spl mu/m InAsP-InGaAsP quantum-well laser diodes obtained with a terahertz-bandwidth frequency comb

We describe an optical method to carry out small-signal frequency response measurements in laser diodes. This method uses a midinfrared tunable femtosecond optical parametric oscillator (OPO), whose frequency spectrum consists of a comb composed by the multiple harmonics of the 81-MHz repetition rate of the same intensity and extending over 2 THz. Tuning of the OPO allows selective generation of carriers in the different regions of the test laser active area without compromising the frequency bandwidth. The small-signal frequency response of the test laser is retrieved from the intensity changes in the frequency comb spectrum. We apply this method to investigate the small-signal frequency response of 1.3-/spl mu/m InAsP quantum-well (QW) lasers. The results of these experiments show that the intrinsic frequency bandwidth of these lasers is limited to less than 10 GHz as a result of state filling and related carrier escape out of the well. An analysis of the frequency response traces through a solution of a system of rate equations allows us to estimate the magnitude of the gain compression associated with this process.     

Traveling wave optical modulator using a directional coupler LiNbO3waveguide

Fabrication methods for low drive voltage and broad-band LiNbO3waveguide directional coupler optical modulator are described. Optical waveguides were prepared by conventionaly Ti in-diffusion into LiNbO3c-cut plate. To obtain wide-band frequency response, traveling wave electrodes were used. Electrode characteristic impedance measured by time domain reflectometry method coincided well with the calculated value by conformal mapping. Measured electrode conductor losses followed square root of frequency. To reduce electrode conductor losses, asymmetric and 3-μm thick Al electrodes were used. Directional coupler optical modulator frequency response was analyzed, using the phase difference average value along the propagation directions. Calculated value by this method coincided well with measured value obtained by a swept frequency technique. The characteristics of this modulator at the 1.317-μm wavelength are as follows: 100 percent modulation voltage is 4 V, extinction ratio is 17 dB, optical insertion loss is 5.4 dB, 3-dB bandwidth is 3.6 GHz, and rise time is about 400ps.     

利用光自注入改善DFB激光器的频率响应

介绍了一种简单有效的自注入方法,通过该方法对直接调制的分布反馈半导体激光器进行光自注入,可以得到非常平坦的频率响应曲线.实验中使用一个环形器和一个1×2耦合器来实现光自注入.实验结果表明,在不同的偏置电流下,适当改变自注入光的偏振状态,频率响应曲线的张弛振荡峰可以得到很好地抑制.     

Frequency response equalization in phase modulated RoF systems using optical carrier Brillouin processing

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.     

Accurate frequency response characterization of photoreceivers

An accurate frequency response characterization method for photoreceivers with optical heterodyne technique is presented in this paper.The characterization is implemented with two single-mode tunable lasers operating near the wavelength of 1.55 μm.The errors introduced by extra fixtures as well as laser output fluctuations are considered and calibrated simultaneously.Compared with previous works,the proposed calibration procedures are more complete.Experimental results indicate that the signific...     

Wideband frequency-response measurement of optical receivers usingoptical heterodyne detection

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     

Small-signal analysis of semiconductor lasers modulated atfrequencies on the order of the beat frequency

A small-signal analysis of direct modulation of laser diodes is presented. The analysis is valid over a wide frequency range, up to the frequency corresponding to the round trip time of the active region. This theory is best for laser diodes with small active regions but with large and complicated optical cavities. Optical resonances may occur in this range, resulting in a large response to direct modulation as a result of interaction of the lasing mode with the optical resonance. This theory can predict the linear response of the laser to direct modulation throughout this frequency range. It also predicts the lower frequency relaxation oscillation effect, thus unifying these different effects with a single treatment. The form of the modulation response is found to be the same as the standard relaxation oscillation formula, modified by a factor the form of which depends on the optics of the laser cavity alone     

垂直腔半导体光放大器频率响应特性研究

从速率方程出发,利用小信号分析方法对垂直腔半导体光放大器(VCSOA)的频率响应特性进行了研究.在考虑了量子阱材料中的增益和载流子浓度之间的对数关系后,得到了VCSOA的峰值响应频率以及3 dB频率响应带宽的解析表达式.结果表明,VCSOA的频率响应特性受抽运光强度、输入光功率以及自发辐射因子的影响.     

用于半导体激光器冷却囚禁原子的声光晶体驱动器及其性能测量

为满足半导体激光器应用于激光冷却囚禁原子的需要,本文设计了输出功率和频率可由外部信号控制的声光晶体驱动器,其输出功率可由0W变至2W,频率由54MHz变至120MHz.提出了F-P腔和声光晶体双通过装置联用来测量其频率动态特性的一种方法,对驱动器的频率和功率动态性能进行了测量.     

相位敏感光时域反射系统低频响应性能优化

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。