吸收区偏置对稳半导体激光器输出特性的影响

文章从两段式吸收型双稳半导体激光器的速率方程组出发，数字模拟了在不同的吸收区偏置下，ＴＡＢＬ的输出功率、输出波长和输出电流环宽度等重要特性的变化，并对获得的结果进行了分析。     

吸收区偏置对双稳半导体激光器输出特性的影响

文章从两段式吸收型双稳半导体激光器（ＴＡＢＬ）的速率方程组出发，数字模拟了在不同的吸收区偏置下，ＴＡＢＬ的输出功率、输出波长和输出电流环宽度等重要特性的变化，并对获得的结果进行了分析。     

吸收型双稳半导体激光器

对两段式吸收型双稳半导体激光器的速率方程组进行了解析求解,并逐点跟踪定义双稳环的关键点,确立了介质发射截面与双稳环宽度和高度的关系式。     

射线法研究两段式半导体激光器模谱

由于两区载流子密度不同，两段式双稳半导体激光器（ＴＢＬＤ）两区界面反射不为零，这将使器件的输出模谱变得复杂，利用射线法，推导了ＴＢＬＤ的端面输出模谱表达式，在此基础上讨论了界面反射的影响以及由界面及端面构成的子腔对模谱的调制。     

用单一表达式研究由两腔组成的半导体激光器

用射线法导出两段式半导体激光器的端面输出谱。该结果既适用于两段式双稳激光器，也适用于简单的外腔式激光器，于是，我们首次用一个统一的式子对这两种看起来颇为不同的器件的某些特性进行了研究。     

两段式半导体激光器的双稳条件

对Ｋｕｚｎｅｔｓｏｖ采用的速率方程加以修正，考虑了俄歇效应的影响，载流子寿命不再作为常数处理，而写成载流子浓度的函数。由此导出了两段式半导体激光器存在双稳的必要条件，计算结果表明，吸收区偏置电流对双稳条件影响极大，对具体器件而言，若增益区和吸收区隔离电阻不够大，几个ｍＡ的偏置电流泄露到吸收区就使器件难以产生双稳。     

两段式双稳半导体激光器下跳阈值点的确定

对Ｋｕｚｎｅｔｓｏｖ采用的速率方程加以修正，考虑了俄歇效应的影响，我们流子寿命不再作为常数处理，而写成载流子浓度的函数。由此导出了两段式双稳半导体激光器下跳阈值点载流子浓度所满足的隐函数解析表达式。通过该解析表达式确定出了器件存在双稳的必要条件。进而讨论了俄歇复合系数、吸收区偏置电流和长度等对双稳特性的影响。     

两段式双稳半导体激光器的行波研究

采用行波速率方程组对两段式双稳半导体激光器进行理论分析，推导出了腔内光子通量的隐含形式解。利用解析结果，可以进一步探讨双稳半导体激光器的特性。     

研究双稳半导体激光器的新方法──逐点跟踪法＊

逐点计算非均匀泵浦半导体激光器输出双稳环上四个关键点处的运行参量,对吸收型双稳半导体激光器进行了研究。该法不但可以给出双稳激光器“启动”和“下跳“点的阈值电流和相应的输出功率,而且还可以给出用这些值来表示的增益截面的解析表达式,这将使得实验上可以简单地由测量到的双稳环的宽度和高度来确定难于测定的增益截面。     

GaAs/GaAlAs光双稳激光器稳态及动态特性的实验研究

本文报道了GaAs/GaAlAs侧向增益波导限制双稳激光器的静态及动态实验结果,对L—1特性,通态模式竞争、延迟特性、张弛振荡、有脉动、混沌现象等进行了研究,并对结果进行了讨论。实验表明,对于双区共腔双稳激光器,由于腔内可饱和吸收体的存在,使得其稳态及动态特性比普通均匀注入激光器复杂,与之有关的物理研究尚待进一步开展。     

Analysis of the cross-coupled lateral mode in a twin-stripefour-contact laser with diagonal current injection

Cross-coupled resonant lateral modes in a twin-stripe four-contact laser are analyzed by coupled-mode theory for conditions in which the current injection into each diagonal pair of stripes is equal. The dependence of the optical power distribution on the laser length and on the carrier-density or the current-density distribution is investigated. The most interesting result is that the highest optical power interesting result is that the highest optical power appears in the waveguide with the lowest carrier density when the carrier-density difference between the adjacent waveguides is small and the laser is shorter than the coupling length. This makes it possible to show that a cross-coupled mode can be supported even in a two-contact twin-stripe laser and that bistable switching between the mode and its mirror image is possible     

Ultrashort Pulses From a Mode-Locked Diode-Oscillator Yb-Fiber-Amplifier System

Ultrashort optical pulses are generated using a hybrid master oscillator power amplifier source. Pulses 2.2 ps in duration generated by a two-contact, bent-waveguide passively mode-locked semiconductor laser are amplified in a ytterbium-doped fiber amplifier to an average power of 0.8 W. External pulse compression yields durations as low as 765 fs with peak powers as high as 0.9kW. Amplification of the harmonically mode-locked diode output has also been demonstrated at the eighth harmonic     

Dynamics and stability of complex-coupled DFB lasers withabsorptive gratings

The basic influence of the saturable nature of absorptive gratings in complex-coupled DFB lasers are investigated, using a simplified model with an extended set of rate equations. It is demonstrated that the coupling coefficient depends on the bias condition and affects all essential laser properties like the static frequency shift, the P-I characteristic and modulation response. In addition, stability problems, like bistable behavior or pulsations, may occur in these devices. Therefore, design rules and approximate criteria for stable laser operation are derived     

Bistability and hysteresis in phase-conjugated reflectivity

An externally driven nonlinear Fabry-Perot interferometer with bistable transmission characteristics is probed through a weak optical field. The nonlinear interaction among the counterpropagating pump beams and the probe beam generates the phase-conjugated beam through intracavity degenerate four-wave mixing. It is shown that the phase-conjugated reflectivity displays bistability and that hysteresis as the driving field is varied in a continuous manner. The analysis is carried out in the mean-field approximation and is valid for the case of low absorption and a high-Qcavity. Both the dispersive and the absorptive effects arising due to saturation of the one-photon resonance are included, and their effect on the phase-conjugated reflectivity is discussed. The results show that, when a bistable device switches on, the reflectivity decreases by a few orders of magnitude. We discuss possible applications and suggest materials where the proposed effects can be seen.     

Saturable interferometer theory of optical bistability

The phenomenon of purely absorptive bistability is examined using a self-consistent multibeam interference method. A state equation is derived and shown to be identical to that derived from mean-field theory (MFT) in the limit of small absorption length products and high saturation. Using the theory given, we are able to examine the time evolution of the system analytically. The results show a critical slowing behavior near the bistable points of the system and are used to examine switching times. In addition, we give a different condition for bistability which results in a larger range of admissibleCvalues.     

Intensity independent bistable polarization switch based on orderedGaInP

We present a polarization sensitive device showing an adjustable bistable switching behavior. It exhibits switching contrasts of up to 30 dB, electrooptical gains of 40 dB, and an angle hysteresis which can be tuned between 0° and 60°. Furthermore, the polarization characteristics are independent of the incident optical power     

Electrical properties of multi p-n junction devices

The electrical properties of multi p-n junction devices are analyzed. It is found that this type of device possesses bistable characteristics similar to that of a Shockley diode and thus provides an alternative realization of devices for switching applications. The inherently greater current gains involved in the operations of such a device yield in principle higher breakover voltages and higher holding currents. Furthermore, the incorporation of heterostructures in this device introduces a new degree of freedom in tailoring their switching characteristics. Multi p-n heterojunction devices operating as SCR lasers were fabricated, and the experimental results are presented.     

Complementary optical bistable switching and triode operation using LiNbO3directional coupler

Optical bistable switching and optical triode operation have been carried out using an optical directional coupler switch fabricated by Ti diffusion into LiNbO3at the 1.15 μm wavelength. The on/off ratio in conventional bistable switching was 10 dB and that in complementary bistable switching was 13 dB. Amplification gain in triode operation controlled by laser diode was 4.8 dB. Complementary operation was found to reduce feedback gain and to improve the on/off ratio in optical bistable switching.     

用光电混合双稳态回路构成的光学多值逻辑门

利用双稳态激光二极管(BILD)或双稳态发光二极管(BILED)回路首次得到了光学多值逻辑。实验上演示了补、与、或、循环和阈等基本的三值逻辑函数,并给出了三路选择开关线路的设计。     

声光双稳态混沌通讯的理论研究

本文利用外信号对声光双稳系统混沌进行了扩展研究,在此基础上提出了基于声光双稳系统混沌通信的方案,并进行了此混沌保密通信的数值模拟。