Frequency locking in a semiconductor laser with double incoherent optical feedback

Frequency locking (FL) in a semiconductor laser with double incoherent optical feedback is experimentally studied, and the characteristics of the locking states are analyzed through comparing the RF spectrum of double incoherent optical feedback and single incoherent optical feedback. Moreover, by varying the external loops length ratio, different orders of frequency locking states are observed. The influence of feedback strength and cavity length on locking performance is preliminarily investigated and the optimized FL state is obtained. This experimental investigation may offer a method to obtain frequency spacing tunable discrete broad-band signals.     

Observation of optical bistability in a GaAlAs semiconductor laser under intermodal injection locking

Experimental observation of optical bistability in a semiconductor laser under intermodal injection locking is reported for what is believed to be the first time. It is seen that a change in injection power of several microwatts or master laser frequency detuning of a few hundred megahertz can induce a change of as much as several hundred gigahertz in the lasing frequency of the slave laser. The results are in qualitative agreement with theoretical predictions.     

Optical bistability in low-dimensional semiconductor heterostructures under cw pump laser and infrared pulse signals

We have investigated theoretically the optical bistability (OB) and optical multistability in quantum-well (QW) semiconductor heterostructures. The effect of a cw pump laser field and a control infrared pulse signal on OB is discussed. It is found that the OB threshold can be controlled by varying the strength of applied fields. It is also shown that OB can be switched to optical multistability or vice versa just using an appropriate relative phase of applied fields. This investigation may open up some new possibilities for applications in all-optical switching in quantum-well structures.     

Quantum dot semiconductor laser with optoelectronic feedback

The optoelectronic feedback (OEF) in quantum dot semiconductor lasers (QD SLs) is studied theoretically where a model includes wetting layer ground state and excited state for QDs are included separating electrons and holes in their dynamics. Both positive and negative OEF are studied. The time series of photon density, the phase portraits of carriers in the states are studied. The parameters affecting OEF are examined where an excitability is seen. The QD SL is found to be more sensitive to the changes in time delay compared with other SLs and a complicated routs are seen in the behavior of QD SL.     

Multimode semiconductor laser with selective optical feedback

We study a multimode semiconductor laser subject to moderate selective optical feedback. The steady state of the laser is destabilized by a Hopf bifurcation and exhibits a period-doubling route to chaos. We also show the existence of a heteroclinic connection between a saddle node and an unstable focus that can be associated with experimentally observed multimode low-frequency fluctuations. This heteroclinic connection coexists with a chaotic attractor resulting from the period-doubling process.     

双光反馈半导体激光混沌系统中外腔延时反馈特征的抑制

在一个双光反馈半导体激光混沌系统中,固定其中一个反馈腔镜(固定腔M₁)的反馈延迟时间以及反馈强度,实验研究了另一个反馈腔镜(可变腔M₂)的反馈延迟时间以及反馈强度对系统混沌输出的延时反馈特征的影响.研究结果表明:在可变腔M₂与固定腔M₁的反馈强度相等的条件下,改变M₂的腔长,当其腔长约等于(但不能严格等于)M₁的腔长或者腔长的一半时,系统将呈现较好地抑制延时反馈特征效果;当M 关键词： 半导体激光器 双光反馈 混沌输出 延时特征     

Mode structure of a semiconductor laser subject to filtered optical feedback

We present an analytical study of the mode structure of a semiconductor laser subject to filtered optical feedback (FOF). First, we derive expressions for the solution sets that define the structure of the modes. We then employ continuation techniques to investigate how this structure changes as filter width, filter detuning and feedback phase are varied. This leads to a comprehensive picture of the FOF laser’s mode structure. In particular, we find an equation for the boundary of the parameter region in which one finds two separate components of modes.     

延时反馈半导体激光器双劈控制混沌方法研究

提出延时反馈半导体激光器双劈控制混沌方法,建立有劈控制的激光动力学物理模型.通过调节激光器外腔光路中的光器件劈去控制反馈光光程,改变了反馈光的延时时间和反馈强度,在物理上实现了延时时间和反馈强度的双参数混沌控制.数值结果证明该方法可以控制激光混沌到周期态,能使激光器输出光脉冲平均功率增加. 关键词： 混沌 控制 劈 双参数     

Low frequency fluctuations in a multimode semiconductor laser with optical feedback

We study a multimode semiconductor laser subject to a moderate optical feedback. The steady state is destabilized by either a simple Hopf bifurcation leading to in phase dynamics or by a degenerate Hopf bifurcation leading to antiphase dynamics. The degenerate bifurcation is also a source of multiple coexisting attractors. We show that a simple interpretation of the low frequency fluctuations in the multimode regime is provided by a chaotic itinerancy among the many coexisting unstable attractors produced by the degenerate Hopf bifurcation.     

基于注入锁定法布里-珀罗激光器的光学双稳态及光存储研究

研究基于注入锁定法布里-珀罗激光器的全光双稳态效应及其在全光存储中的应用. 进行了法布里-珀罗激光器的注入锁定的实验研究, 对注入锁定的法布里-珀罗激光器的输出功率特性进行实验分析, 得到了不同注入光波长失谐量对迟滞曲线的门限宽度和消光比的影响. 进一步, 通过对控制信号功率的合理设置, 实现了对10 Gb/s输入信号的2.5 GHz光存储验证了利用注入锁定法布里-珀罗激光器实现高速全光存储的可行性, 在高速光纤通信领域具有极大的应用价值.     

Optical bistability in a three-level semiconductor quantum-well system

Optical bistable behavior in a unidirectional ring cavity (or a Fabry–Pérot cavity) containing a semiconductor quantum well, described as a three-level ladder-type system with similar transition energies, has been studied. The system interacts with a strong driving field which is in two-photon resonance with the intersubband transition and thus simultaneously drives all three levels into phase-locked quantum coherence. The threshold for switching to upper branch of the bistable curve is found to be reduced due to the presence of quantum interference. Such system can be used for making efficient and fast all-optical switching devices. PACS 78.67.De; 42.50.Hz; 78.20.Bh     

Optical bistability in semiconductor lasers

Optical and Quantum Electronics -     

Frequency stabilization of multiple semiconductor lasers using digital feedback loop

We propose and demonstrate a simple technique to stabilize the frequencies of multiple semiconductor lasers simultaneously using a Fabry-Perot etalon filter and a digital signal processing. Unlike other stabilization techniques, the proposed technique could stabilize DFB lasers using only one digital feedback control loop. The result shows that the proposed technique could maintain the frequency stability of 16 DFB lasers within ±150 MHz.     

High-frequency optical signal generation in a semiconductor laser by incoherent optical feedback

This work examines the feasibility of using incoherent optical feedback to generate high-frequency optical signals in a semiconductor laser. At a roundtrip feedback distance of 30 cm, a signal appears at around 1 GHz while the laser output is kept in single longitudinal mode and single polarization. The proposed method does not use any external modulation or saturable absorber. Some of the signal's properties are discussed as well.     

外腔反馈对半导体激光器振荡特性的影响

通过有效反射系数的引入，根据激光谐振腔的自再现条件和对腔内光子密度、载流子密度方程的求解，分析了外腔反馈对半导体激光器的阈值增益、振荡频率和输出功率等振荡特性的影响，并通过实验进行了验证.外腔反馈后，半导体激光器的阈值电流从420mA降为370mA，输出功率的斜率效率获得了提高，理论计算的输出功率曲线与实验结果符合的很好. 关键词： 半导体激光器 外腔反馈 振荡特性     

存在外部光反馈的半导体激光器的相位噪声

本文在理论上研究了由于外部光反馈引起的半导体激光器的相位噪声.理论分析是通过引入一个反馈耦合率K和线性化速率方程,导出了半导体激光器相位噪声功率谱密度的表达式.这表明相位噪声功率谱密度随外腔长度而周期性地漂移,且功率谱密度的峰值随外部反馈耦合率而发生很大的变化.     

Parameter optimization of microcantilevers optically excited by a semiconductor laser with optical feedback

A novel approach of optically exciting and detecting the vibration of a microcantilever by a sinusoidally driven semiconductor laser subject to optical feedback is proposed. A theoretical model for the approach is established, and the working parameters are optimized. In our experiments, an Al-coated microcantilever is designed with the optimized working parameters, and the microcantilever is optically excited by a sinusoidally driven semiconductor laser. We have demonstrated that there exist periodic dips of the optical power of the semiconductor laser, which is caused by the resonant vibration of the microcantilever. The optical power of the semiconductor laser is also analyzed theoretically by using the Lang–Kobayashi (L–K) equations. The experimental result is consistent with the result of theoretical analysis.