Optical bistability in semiconductor lasers

Optical and Quantum Electronics -     

Modal bistability in twin-ridge injection lasers

This paper reports on the first observations of a promising new form of optically triggered modal bistability in semiconductor lasers. The bistable mechanism involves a switch between the degenerate in-phase and antiphase coupled modes of an index-guided, twin-ridge laser operating at 1.3 μm wavelength. Experimental results have indicated sub-picojoule bistable switching with switching times of less than 250 ps. Possible limitations of device performance are discussed, with particular reference to asymmetry of the ridge structure.     

Single-parameter characterization of bistability in double contact injection lasers

We show that for the Lasher-Basov model of a double contact injection laser the hysteresis in the light output as a function of the driving current in the gain region can be characterized by a single parameter.     

All-optical set-reset flip-flop based on frequency bistability in semiconductor microring lasers

The electric field of the modes of semiconductor microring lasers (SMRLs) in the presence of bus waveguide reflections are linear combinations of the clock wise (CW) and the counter clock wise (CCW) electric fields. The mode structures can be controlled by the waveguide reflection coefficients. The power ratio and phase difference of the CW and CCW fields of one mode is proportional to the ratio of the reflection coefficients of the left and right waveguides. It is shown that the degenerate CW and CCW modes in the presence of bus waveguide reflections are split into two modes with different frequencies. Employing these new modes, SMRL can be used as an element to design flip-flops used in photonic integrated circuits. For a symmetric structure, the inter-frequencies of CW and CCW waves relating to each mode can be considered as the output of the optical flip-flop. Output of asymmetric mode is zero while the symmetric mode has a nonzero output.     

Modulation behavior of semiconductor injection lasers

GaAs double heterostructure semiconductor injection lasers which now exhibit more than 25000 h cw room temperature lifetime are of great interest for future use as directly modulated transmitters for high bit-rate fiber optical communications. The effects limiting this application are modulation distortions, spectral width and additional spectral broadening in the case of modulation and spontaneous fluctuations of the output power. The dynamic and spectral behavior of injection lasers, the methods of high bit-rate modulation and the improvement of the high bit-rate modulation capability by coupling two lasers are discussed.     

Optical waveguiding in semiconductor injection lasers and integrated optics

Weak perturbations from various refractive index distributions have been introduced into the central layer of the three layered dielectric slab optical waveguide model and solutions of the wave equation in this guide for TE modes have been compared with the results published for the unperturbed mode. The perturbations in general introduce quadrature components in the transverse modes and a mode width dependent amplitude. The mode position within the guide can be shifted and the mode width increased or decreased. With increasing parabolic perturbation there is increasing waveguide discrimination against higher order modes.     

Near-field extinction in semiconductor lasers under optical injection

The optical injection sensitivity of twin-stripe lasers has been characterized in terms of an extinction ratio whose value has been calculated as a function of optical injection power. It is shown that significant changes in the lasing field intensity of the device may be achieved using injected optical power comparable to the output of twin-stripe lasers. The effects described are seen to be relevant to a prediction of optically induced bistability made in an earlier work.     

Absorptive optical bistability at microwave frequencies

Summary Intrinsic absorptive bistability and hysteresis cycles in a steady-state regime are obtained at microwave frequencies. A theory is presented which takes into account the Gaussian shape of the fundamental mode excited into the resonator and is compared with the experimental results.

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Riassunto Sono state osservate la bistabilità assorbitiva intrinseca e l’isteresi nel caso stazionario, operando alle frequenze delle microonde. Si presenta una teoria che tiene conto della forma gaussiana del modo fondamentale eccitato nel risuonatore e che è confrontata con i risultati sperimentali.

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Резюме На микроволновых пастотах наблюдаются внутренняя абсорбционная бистабильность и гистерезисные циклы в стационарном режиме. Предлагается теория, которая учитывает гауссову форму основной моды, возбужденноц в резонаторе, и которая сравнивается с экспериментальными резулстатами.

     

Epstein-layer and dielectric-slab electromagnetic models of semiconductor injection lasers

This paper is devoted to a comparison of two electromagnetic models of junction lasers — the dielectric slab and the Epstein layer. The main emphasis is on the discussion of possible methods of matching the parameters appearing in both models. The threshold condition for active layer thickness and mode frequency at a given gain and mode number is solved numerically. It is shown that the discrepancies between both models become reasonably small when a proper method, involving averaging of the dielectric constant over the active and passive regions, is applied. The cases of the three lowest order TE transverse modes of homojunction, single-, and double-heterojunction lasers are considered. The obtained results suggest that the Epstein-layer model can approximate experimental data as well as the dielectricslab model does.     

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.     

Photorefractive saturable absorptive and dispersive optical bistability

It is shown that photorefractive wave-mixing gives saturable gain, saturable absorption and Kerr-like nonlinear phase retardation. An analogy between photorefractive two-beam coupling and two-level atom system is then drawn. We investigate optical bistability in a ring cavity, utilizing these phenomena, and compare our results with classical absorptive and dispersive optical bistability.     

注入半导体激光器混沌相位周期控制方法研究

提出外部光注入半导体激光器混沌相位控制方法，通过周期调制注入光的相位相移将激光器的混沌控制到多种周期状态.数值结果表明：在不同强度光注入下，(1)通过半波长周期相位相移调制控制混沌激光到周期态、双周期态、三周期态、四周期态以及多周期态等；(2)通过四分之一波长周期相位相移调制控制混沌激光到周期态和多周期态，并在高频调制控制时能够产生激光锁模现象，其锁模区域是19—21GHz；(3)波长周期相位相移调制控制也能使混沌激光控制到三周期态和多周期态等. 关键词： 混沌 控制 激光器 周期     

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.     

Self pulsing inm dispersive optical bistability

We analyze the stability of the stationary solutions of dispersive optical bistability in a ring cavity for a homogeneously broadened atomic system. The analysis is performed in the limit αL ? 1, with $\text{C =}\text{αL}\text{2}\text{T}$ fixed. It is shown that in the dispersive case one can yield instability also when bistability is absent. This feature suggests that the dispersive case is more suitable than the purely absorptive one with respect to the observation of the self-pulsing behavior.     

Electric equivalence of dispersive optical bistability

A general criterion for bistability of transmissive devices, either of electronical or optical nature, is described and its applicability to dispersive optical bistability is demonstrated. Subsequently an electric equivalent circuit for dispersive optical bistability is proposed. A numerical analysis shows clearly bistable behaviour of the circuit.     

Open loop synchronization of semiconductor lasers with periodical injection

In this paper, the influence of fluctuation amplitude and frequency of the injection field on the dynamics and synchronization of semiconductor lasers are studied numerically. The fluctuation amplitude and frequency of the injection field are controlled by external modulation of the master laser. In the simulation, we use a modified correlation coefficient named similarity index to evaluate the synchronization performance. The results show that frequency and fluctuation amplitude of the injection field play important roles on the dynamics and synchronization quality of the system. Large fluctuation amplitude and moderate fluctuation frequency of the injection field will contribute to the synchronization of the two lasers. The results can also be extended to the analysis of chaotic signals.     

The role of diffraction in dispersive optical bistability

A finite difference method is applied to the study of diffractive effects in dispersive optical bistability. Although quite elementary, the method produces extensive results in an efficient way. A detailed comparison is made with previous quasi-fast Hankel transform results, and the approach to the diffractionless limit is discussed.