光电子技术

TNZ 2003060109控制光和信号光预差对太肠兹筑润乍对称解盆用器性能的影响/温亮生,伍剑,林金桐(J晾邮电大学)11光学学报.一2003,23(6)一656一661讨论了半导体光放大器中的带间效应,及载流子热效应、谱烧孔效应、双光子吸收以及超快非线性折射等带内效应对半导体光放大器的动态特性的影响,讨论了两种情况:l)保持控制光波长不变而改变信号光频率,2)保持控制光和信号光频率相同而同时改变它们的颇率下半导体光放大器的增益、相位动态特性以及太赫兹光非对称解复用器的开关窗口特性.数值结果表明,为了得到较为平坦而窄的开关窗口,控制光波长应…     

双辅助光作用下半导体光放大器性能分析

半导体光放大器以其良好的非线性在全光网络中具有广泛应用,但较长的载流子恢复时间一直是制约其用于超快全光信号处理的速率瓶颈,基于包含自发辐射噪声的半导体光放大器模型,探讨了提高半导体光放大器增益恢复时间的有效途径,通过对制约透明波长移动,增益饱和与有效载流子寿命的相关因素进行数值分析,得出以下结论:与单辅助光相比,采用双辅助光可以在不牺牲信号增益的前提下进一步缩短载流子寿命,因而是提高半导体光放大器增益恢复时间的有效途径,这一点对工程设计和应用具有一定的指导意义.     

半导体激光放大器对超短光脉冲串的动态响应

本文利用速率方程从理论上研究了行波式半导体激光放大器(TWA)对来自主动锁模半导体激光器的皮秒脉冲串的动态响应,计算了脉冲串的动态增益、TWA的载流子的时间空间变化,本文首次使用光脉冲光子数(对应于脉冲能量)表示法研究TWA,动态增益饱和只与脉冲光子数有关,与输入功率无关,此外讨论了一些全光通信系统中与TWA有关的问题。     

太赫兹光非对称解复用器中自发辐射噪声特性分析

提出了一个在超短脉冲注入半导体光放大器 (SOA)时 ,在考虑了半导体带间效应以及带内效应 ,包括载流子热效应、谱烧孔效应、双光子吸收效应以及超快非线性折射效应的自发辐射噪声的计算模型。并利用该模型计算了放大自发辐射 (ASE)噪声对太赫兹光非对称解复用器 (TOAD)开关性能的影响。数值结果表明 ,在考虑ASE噪声情况下 ,TOAD的开关窗口的边沿更陡 ,在开关窗口的尾部还会出现明显的小峰。结果还表明 ,在输入为理想孤子脉冲下 ,即使考虑ASE噪声 ,在TOAD处于开的状态时 ,其输出信号的信噪比也大于 2 5dB。     

半导体光放大器中超快增益压缩效应与TOAD开关性能优化

在半导体光放大器中当光脉冲小于１０ｐｓ时除了考虑线性增益饱和效应,还必须考虑超快增益压缩效压。本文用数值方法分析了超快增益压缩效应对ＴＨｚ光非对称解复用器（ＴＯＡＤ）的开关特性。经过细致的参数优化,采用２．５ｐｓ控制光,可以克服开关窗的分裂效应,得到一个宽度为２．０ｐｓ,消光比为１３．７ｄＢ的开关窗。     

基于QD-SOA交叉增益调制的波长转换研究

量子点半导体光放大器具有比传统半导体光放大器更快的载流子恢复时间,基于QD-SOA交叉增益调制的波长转换技术具有转换速率快,无pattern effects效应的特点.对有源区长度,输入信号光功率和转化后信号的消光比和脉冲展宽进行了研究,对提高基于QD-SOA交叉增益调制波长转换的性能具有指导意义.     

行波半导体光放大器的增益饱和及其在解复用技术中的应用

本文通过对行波半导体光放大器增益饱和及其瞬态增益特性的分析，指出了利用半导体光放大器增益饱和快的特点，可使半导体光放大器环路镜实现超高速的解复用功能。     

量子点半导体光放大器的速率方程和增益特性

为了深入研究量子点半导体光放大器(QD-SOA)的特性,建立了量子点半导体光放大器子带导带的三能级系统模型.把系统载流子的速率方程与其他文献采用的速率方程进行了对比优化.通过数值计算得到了瞬态解,并得到载流子在放大器各能级态的浓度分布,验证了量子点中能级分立特性.利用电子和空穴各自的占有几率在基态成一定的线性关系,在稳态下对速率方程求解,得出了量子点半导体光放大器相关的增益特性,以及增益特性与基态电子的占有几率之间的关系.结果表明量子点半导体光放大器具有很高的饱和增益和微分增益,较低的阈值电流等特性.说明量子点半导体光放大器具有比其他体材料和量子阱光放大器更加优异的特性.为光放大器的设计提供了有力的理论指导.     

垂直腔半导体光放大器增益的理论分析

针对研究增益饱和时,现有的垂直腔半导体光放大器(VCSOA)速率方程模型在确定输入信号的功率注入因子方面存在难题,根据法布里-珀罗腔边界条件,从行波方程和与位置相关的载流子方程出发,引入随轴向位置发生变化的增益增长因子刻画微腔内的驻波效应,构建出VCSOA的增益模型。利用该模型通过求方程的自洽得到了腔内载流子、光子的分布,并分析了反射增益,其结果与已报道的理论及实验基本一致。     

增益开关半导体激光器的三级脉冲整形方案

增益开关半导体激光器产生的光脉冲宽度往往较宽,且具有一定大小的脉冲基座。为了提高增益开关半导体激光器的脉冲质量,提出了一种三级脉冲整形方案。首先,利用色散补偿光纤将增益开关半导体激光器输出的光脉冲宽度从39.381 ps压缩到26.681 ps,随后利用掺铒光纤放大器和色散位移光纤的高阶孤子效应进一步将光脉冲的宽度压缩到20.916 ps,最后利用半导体光放大器的自相位调制效应区分开脉冲基座与脉冲中心的光谱,并利用光滤波器滤除脉冲基座对应的光谱部分,从而消减脉冲基座,并将脉冲宽度压缩到18.497 ps。实验结果表明,该三级脉冲整形方案可以有效地压缩脉冲宽度以及减小脉冲基座,从而提高增益开关半导体激光器输出光脉冲的质量。     

Transmission performance of chirp-controlled signal by usingsemiconductor optical amplifier

We examine the fiber transmission performance of the optical signal whose chirp is controlled by utilizing phase modulation in semiconductor optical amplifier (SOA) with both simulations and experiments. This chirp control technique converts a positive chirp created by electroabsorption (EA) modulator into negative chirp, which reduces the waveform degradation due to the chromatic dispersion in transmission over standard single-mode fiber (SMF). It also provides an optical gain that is sufficient to compensate the insertion loss of the EA modulator. We investigate how the chirp control is affected by the input power to the SOA and the carrier lifetime of the SOA. As the SOA input power increases, the negative chirp becomes large, while the waveform is largely distorted due to gain saturation. However, the waveform distortion at high SOA input powers can be shaped by using a frequency discriminator. The acceleration of the carrier lifetime also reduces the waveform distortion due to gain saturation. We demonstrate that the chirp control technique is effective even for a high bit rate optical signal up to 10 Gb/s, when the carrier lifetime is expedited by optical pumping     

Influence of fast gain depletion on the dynamic response of TOAD's

The operating characteristics of the terahertz optical asymmetric demultiplexer (TOAD) devices subject to picosecond control pulses have been investigated taking into account gain saturation and nonlinear gain compression, due to carrier heating and spectral holeburning. It is shown that when the control pulse width is less than ~2 ps, fast gain depletion process appears in the time resolved gain dynamics of the SOA. The fast depletion process leads to an oscillating output power structure in the switched region. The oscillatory structure is found to persist for over 1 ps and sets a limit on the practical utilization of these devices     

Electron–Hole Plasma-Induced Spectral Blueshift of Optical-Data Injection Mode-Locked Semiconductor Optical Amplifier Fiber Laser

Under an optical nonreturn-to-zero (NRZ) data injection at 10 Gbit/s, the 10-GHz mode-locking and pulsed return-to-zero (RZ) clock extraction from a semiconductor optical amplifier (SOA) based fiber ring is investigated in this paper. The diagnoses on gain and intracavity-power-controlled anomalous blueshifted spectrum and subpicosecond timing jitter are demonstrated. By increasing the injecting power of the optical NRZ data from ${-}3$ to 8 dBm into the SOA bias at different currents, the mode locking is completed with a dc level greatly decreasing from 480 to 50 $mu$ W (only 1.5% of the mode-locked pulse power at 3 mW), corresponding to a pulse/dc amplitude contrast ratio up to 18 dB. Increasing the SOA bias current up to 350 mA significantly suppresses the timing jitter from 1.8 ps to 345 fs, and the extracted RZ clock pulse is shortened from 55 to 27 ps. The pulsewidth of the amplified SOAFL is compressed from 11 ps to 836 fs after dispersion compensation. At constant data injection level, the increasing SOA bias or gain oppositely redshifts the mode-locked SOA fiber ring laser (SOAFL) spectrum by 5 nm. The amplifier spontaneous emission of SOA at short wavelength region (${sim} {hbox {1520}}$ nm) is eliminated with increasing NRZ data power, whereas the mode-locking gain peak arises and blueshifts from 1558 to 1552 nm due to the band-filling effect. Such a blueshift in mode-locking spectrum becomes more significant in SOA at lower bias (or gain) condition. A theoretical model interprets the correlation between the nonlinear gain suppression-induced variation of electron–hole plasma in SOA and the blueshifted mode-locking SOAFL spectrum, which is occurred when the gain saturation condition for the SOA becomes more pronounced.      

基于半导体光放大器交叉增益饱和的波长转换的理论分析

建立了基于半导体光放大器交叉增益饱和的波长转换的理论模型。分别讨论了小信号下波长转换特性和大信号下转换波形的畸变情况。结果表明,半导体光放大器的载流子寿命是导致输出波形畸变的主要因素。     

Gain saturation characteristics of traveling-wave semiconductorlaser amplifiers in short optical pulse amplification

The gain saturation characteristics of traveling-wave semiconductor laser amplifiers (TWAs) are theoretically and experimentally investigated. In the amplification of an isolated pulse whose repetition period is short compared to the carrier lifetime, the gain saturation is related through the carrier lifetime to the gain saturation in CW amplification. When the output pulse energy is smaller than the saturation energy, short optical pulses can be amplified without pulse shape distortion, whereas high-energy pulses suffer from pulse shape distortion due to the temporal gain variation during the pulse radiation. FWHM pulse duration variation in amplification by TWAs depends on the input pulse shape. The pulse energy gain saturation was experimentally confirmed to be independent of pulse durations and to be determined only by the pulse energy. In extremely-high-repetition-rate pulse amplification, the saturation of the pulse energy gain is determined by the average signal power     

Reducing crosstalk and signal distortion in wavelength-division multiplexing by increasing carrier lifetimes in semiconductor optical amplifiers

A simple theory for the crosstalk in multichannel wavelength-division multiplexing (WDM) communication systems caused by the cross gain saturation in semiconductor optical amplifier (SOA) is developed. It is shown that increasing the carrier recombination lifetime while reducing the differential gain in the SOA greatly mitigates the crosstalk. An SOA using type-II quantum wells with reduced recombination probability is designed, and its characteristics are numerically modeled for a number of different WDM systems. It is shown that when used as a preamplifier or in local/metro networks with a small number of amplifiers, error-free transmission can be achieved with the type-II SOA.     

Analysis of basic four-wave mixing characteristics in asemiconductor optical amplifier by the finite-difference beampropagation method

We have numerically analyzed nondegenerate four-wave mixing (FWM) among short optical pulses in a semiconductor optical amplifier (SOA) by the finite-difference beam propagation method (FD-BPM). We used the nonlinear propagation equation taking into account gain spectrum dynamic gain saturation which depends on carrier depression, carrier heating, and spectral hole-burning, group velocity dispersion, self-phase modulation, and two-photon absorption. To analyze FWM in an SOA, the evolution in time and spectral domain of two input optical pulses with different frequencies during propagation was calculated. From this simulation, it has become clear that the method me used here is a very useful technique for simulating FWM characteristics in SOA's. We also found that the wavelength dependence of the gain is crucial if the detuning is larger than 1 THz     

半导体光放大器的快速饱和效应及其长度对TOAD解复用器性能的影响

分析了半导体光放大器 (SOA)的快速饱和效应及其长度对 TOAD解复用器性能的影响 ,对小开关窗口和大开关窗口两种工作模式进行了研究。经分析发现 ,半导体光放大器的快速增益饱和效应对开关窗口的形状和开关能量都有很大的影响 ,而且开关能量随控制脉冲宽度的变化关系对两种工作模式是完全不同的。研究表明考虑 SOA长度效应后 ,第二个开关窗口的幅度可大大减小 ,这说明适当地增加半导体光放大器的长度可以进一步降低 TOAD的开关窗口 ,提高 TOAD的速率。