光注入MQW半导体激光器分岔及其动力学稳定性

研究外部光注入多量子阱激光器四维系统动力学行为及其分岔,数值模拟了外部光注入光强度、频差以及激光器线宽增强参数、驱动电流对分岔的影响,分别得到激光由分岔、周期、多周期进入混沌的过程以及激光混沌频谱.给出了多量子阱激光器静态锁模最大频域公式,导出了注入多量子阱激光器四维系统的一次近似下扰动方程和本征值方程及解,给出了该系统的Hopf分岔条件,理论和数值分析了系统的动力学稳定性行为,并进一步模拟得出激光单周期、双周期、六周期时振荡频率等值.     

光注入MQW半导体激光器分岔及其动力学稳定性

研究外部光注入多量子阱激光器四维系统动力学行为及其分岔,数值模拟了外部光注入光强度、频差以及激光器线宽增强参数、驱动电流对分岔的影响,分别得到激光由分岔、周期、多周期进入混沌的过程以及激光混沌频谱.给出了多量子阱激光器静态锁模最大频域公式,导出了注入多量子阱激光器四维系统的一次近似下扰动方程和本征值方程及解,给出了该系统的Hopf分岔条件,理论和数值分析了系统的动力学稳定性行为,并进一步模拟得出激光单周期、双周期、六周期时振荡频率等值.     

InGaAsP量子阱激光器结构与阈值电流密度的关系

计入俄歇复合过程的影响,从理论上研究了InGaAsP多量子阱激光器的阈值电流密度。在评述辐射和俄歇过程中考虑了二维载流子在量子化次能带间的所有可能跃迁。俄歇复合电流强烈地依赖于量子阱结构,这样就需要对量子阱激光器的结构进行精心的设计。此外,还阐述了能获得最低阈值电流密度的InGaAsP多量子阱激光器的结构设计程序。     

共振声子太赫兹量子级联激光器研究

针对四阱有源区、一阱注入区及三阱有源设计,采用蒙特卡洛模拟方法研究了共振声子太赫兹量子级联激光器的性能差异。采用傅里叶变换光谱仪及远红外探测器测量了四阱共振声子太赫兹量子级联激光器的低温电光特性。详细讨论了提高太赫兹量子级联激光器发射功率的方案。     

基于三层模型的多量子阱激光器调制特性的SPICE模拟

从三层速率方程推导出多量子阱激光器的等效电路模型 ,并用数量而不是密度来描述载流子及光子行为 ,避开了传统方法中处处都要涉及到的体积参量 ,解释了传统的二层模型所不能解释的多量子阱 (MQW )激光器中多量子阱内载流子不均匀分布问题 ,用SPICE进行了调制特性的模拟及讨论。激光器件的模拟以层次性的方式实现 ,对使用EDA工具进行集成光学器件和系统仿真进行了探索。     

基于三层速率方程的单量子阱激光器电路模型

量子阱激光器以其优良的性能,成为光通信领域的一种重要光源.在量子阱激光器模型中引入中间过渡态,能更完整地描述阱中载流子的输运过程.对基于三层速率方程的单量子阱激光器电路模型进行模拟分析,探讨了过渡态在载流子输运过程中的作用.其模型仿真的结果对器件设计及不同模型的选用具有十分重要的参考价值.     

小发散角量子阱激光器研究

使用三层平板波导理论分析了半导体量子阱激光器远场分布。针对大功率激光器讨论了极窄和模式扩展波导结构方法减小垂直方向远场发散角,得到了极窄波导结构量子阱激光器远场分布的简化模型,获得了垂直发散角的理论值,垂直方向远场发散角减小为28.6°;使用传输矩阵方法模拟了模式扩展波导结构量子阱激光器的近场光斑及远场分布,垂直方向远场发散角减小为16°。实验测试了极窄和模式扩展波导结构量子阱激光器的垂直发散角,理论结果与实验测试获得的发散角基本一致,实现了降低发散角的要求,获得了小发散角量子阱激光器。     

高功率980nm非对称宽波导半导体激光器设计

设计了980nm非对称宽波导InGaAs/InGaAsP量子阱激光器,并在结构中插入电流阻挡层,有效地阻止载流子的泄露。用LASTIP软件对980nm非对称宽波导量子阱激光器进行理论模拟,与传统的980nm对称宽波导量子阱激光器相比,非对称宽波导量子阱激光器波导和量子阱之间有更小的能带差,非对称宽波导结构具有更低的阈值电流,更高的斜效率以及更低的阻抗,所以带有电流阻挡层的980nm非对称宽波导InGaAs/InGaAsP量子阱激光器有更高的光电转换效率和输出功率。     

半导体激光器激活区中一维量子线的研制

采用一维量子线阵列结构作为激活区的半导体激光器与采用二维量子阱结构激活区的常用激光器相比，具有许多优越的性能。利用能量为４０ＫｅＶ的Ｇａ＾＋离子注入到Ａｌ０．３Ｇａ０．７Ａｓ／ＧａＡｓ二维量子阱，再经白光快速退火，制备了线宽５００￣４０ｎｍ的一维量子线并研究其光电特性。     

半导体激光器激活区中一维量子线的研制

采用一维量子线阵列结构作为激活区的半导体激光器与采用二维量子阱结构激活区的常用激光器相比，具有许多优越的性能。利用能量为４０ＫｅＶ的Ｇａ＋离子注人到Ａｌ０．３Ｇａ０．７Ａｓ／ＧａＡｓ二维量子阱，再经白光快速退火，制备了线宽５００～４０ｎｍ的一维量子线并研究其光电特性。     

一个简单的量子阱激光器等效电路模型

给出一个新的量子阱激光器等效电路模型,由量子阱激光器单模速率方程推导得到并在电路模拟程序ＳＰＩＣＥ中完成。该模型考虑了热辐射效应和分离限制区域（ＳＣＨ）内的载流子工作情况,给出了新的光增益表达式。并利用该模型对单量子阱激光器的小信号特性和瞬态大信号特性进行了预测,模拟结果表明和速率方程的直接求解结果吻合很好。     

Photonic quantum ring laser of 3D whispering cave mode

A new whispering cave mode (WCM), a three-dimensional (3D) case of Lord Rayleigh's 2D whispering gallery modes, based upon 3D total internal reflection is presented, where GaAs quantum well (QW) near-vertical microdisk resonators exhibit a strong carrier-photon coupling for the QW carriers located in the Rayleigh band, generating 2D-to-1D carrier phase transitions of photonic quantum ring (PQR). It is a ‘photonic’ quantum corral effect (PQCE), whose simulation work produces a tangled web pattern of imminent recombinant carriers in picoseconds timescale. The PQCE is responsible for the ultralow threshold currents below 300 nA for a single mode GaAs PQR laser, and a prototype GaN PQR laser with a threshold near and below 1 μA.     

Modeling of GaN optoelectronic devices and strain-inducedpiezoelectric effects

Modeling of nitride-based LEDs and laser diodes requires a fast modular tool for numerical simulation and analysis. It is required that the modeling tool reflects the primary physical processes of current injection, quantum well (QW) bound-state dynamics, QW capture, radiative, and nonradiative transitions. The model must also have the flexibility to incorporate secondary physical effects, such as induced piezoelectric strain fields due to lattice mismatch and spontaneous polarization fields. A 1-D model with a phenomenological well-capture process, similar to that developed by Tessler and Eisenstein, has been implemented. The radiative processes are calculated from first principles, and the material band structures are computed using k·p theory. The model also features the incorporation of such effects as thermionic emission at heterojunctions. Shockley-Read-Hall recombination, piezoelectric strain fields, and self-consistent calculation of the QW bound states with dynamic device operation. The set of equations underlying the model is presented, with particular emphasis on the approximations used to achieve the previously stated goals. A sample structure is analyzed, and representative physical parameters are plotted. The model is then used to analyze the effects of incorporation of the strain-induced piezoelectric fields generated by lattice mismatch and the spontaneous polarization fields. It is shown that these built-in fields can accurately account for the blue-shift phenomena observed in a number of different GaN LEDs     

Photon properties of light in semiconductor microcavities

Properties of atom-like emitters in cavities are successfully described by cavity quantum electrodynamics(cavity-QED).In this work,we focus on the issue of the steady-state and spectral properties of the light emitted by a driven microcavity containing a quantum well (QW) with the excitonic interactions using simulation of fully quantum-mechanical treatment.The system is coherently pumped with laser,and it is found that depending on the relative values of pumping rate of stimulated emission,either one or two peaks close to the excitation energy of the QW or to the natural frequency of the cavity are shown in the emission spectrum.Furthermore,the nonclassical proprieties of the emitted photon have been investigated.This excitonic system presents several dynamical and statistical similarities to the atomic system,in particular for the bad-cavity and good-cavity limits.The results show that the photon emission can be significantly amplified due to the coupling strength between a single emitter and radiation field in the microcavity,and it is concluded that the present semiconductor microcavity system may serve as a QW laser with low threshold.     

Threshold analysis of highly detuned long-wavelength GaAs-based GaInNAsSb/GaNAsQWVCSELs

Comprehensive 3D optical–electrical–thermal-gain self-consistent simulation of physical processes taking place inside a laser volume of the GaAs-based GaInNAsSb/GaNAs quantum-well (QW) vertical-cavity surface-emitting diode laser (VCSEL) is carried out to examine a possibility to reach the long-wavelength room-temperature (RT) continuous-wave (CW) laser operation in highly detuned devices. The RT CW 1.422-μm lasing emission has been found to be reached practically without troubles. However, to reach the 1.5-μm laser wavelength, it is necessary to increase the QW active region temperature by about 100 K, which may be done by a proper increase in the RT CW operation current.     

Nonlinear analysis of quantum-well lasers with the effects ofcarrier transport

An improved nonlinear quantum-well (QW) laser model, which takes into account the effects of quantum capture and escape processes, is presented, based on laser rate equations and Volterra theory. This model is further expanded by proper parameter transform to include the effect of carrier diffusion in the separate confinement heterostructure region. Various QW laser distortions have been evaluated using this model and compared with the results obtained from the previous model where the transport effects are absent. The results shows that the effect of transport processes on laser dynamic nonlinearity can be significant     

“Spiked” GaInP Quantum Wells for Shorter Red Wavelength Emission

Compositional and strain limitations are often restricting the emission wavelength from quantum-well (QW) lasers. The letter presents simulation and experimental results on the effects of including thin higher bandgap layers into GalnP QWs emitting in the short red wavelength range. These were considered "spiked" single QWs since the thin higher bandgap layers used in our studies varied in composition and led to carrier wavefunctions that are like perturbed single QW wavefunctions rather than wavefunctions of coupled QWs. The edge-emitting lasers having up to four-monolayer AlGalnP "spikes" in the QWs had an emission blueshift of up to 25 nm, whereas the degradation of other laser characteristics was in line with the degradation observed when similar emission blueshift was generated by conventional QW modification.     

Effects of electronic current overflow and inhomogeneous carrier distribution on InGaN quantum-well laser performance

Laser performance of several InGaN quantum-well (QW) lasers with an emission wavelength of 392-461 nm are numerically studied with a LASTIP simulation program. Specifically, the effects of electronic current overflow and inhomogeneous carrier distribution on the laser performance of InGaN QW lasers operating at different wavelengths are investigated. Simulation results indicate that the use of an AlGaN blocking layer can help reduce the electronic current overflow and, in addition to the dissociation of the InGaN well layer at a high growth temperature during crystal growth, the inhomogeneous carrier distribution in the QWs also plays an important role in the laser performance. From the simulation results, we conclude that the lowest threshold current density is obtained when the number of InGaN well layers is two if the emission wavelength is shorter than 427 nm and one if the emission wavelength is longer than 427 nm, which are in good agreement with the results observed by Nakamura et al. in their experiments.     

Simulation of carrier transport and nonlinearities in quantum-welllaser diodes

The two-dimensional (2-D) quantum-well (QW) laser diode simulator Minilase-II is presented in detail. This simulator contains a complete treatment of carrier dynamics including bulk transport, quantum carrier capture, spectral hole burning, and quantum carrier heating. The models used in the simulator and their connectivity are first presented. Then the simulator is used to demonstrate the effects of various nonlinear processes occurring in QW lasers. Finally, modulation responses produced by Minilase-II are compared directly with experimental data, showing good quantitative agreement     

High-performance strain-compensated InGaAs-GaAsP-GaAs(λ=1.17 μm) quantum well diode lasers

This letter reports studies on highly strained and strain-compensated InGaAs quantum-well (QW) active diode lasers on GaAs substrates, fabricated by low-temperature (550°C) metal-organic chemical vapor deposition (MOCVD) growth. Strain compensation of the (compressively strained) InGaAs QW is investigated by using either InGaP (tensile-strained) cladding layer or GaAsP (tensile-strained) barrier layers. High-performance λ=1.165 μm laser emission is achieved from InGaAs-GaAsP strain-compensated QW laser structures, with threshold current densities of 65 A/cm² for 1500-μm-cavity devices and transparency current densities of 50 A/cm². The use of GaAsP-barrier layers are also shown to significantly improve the internal quantum efficiency of the highly strained InGaAs-active laser structure. As a result, external differential quantum efficiencies of 56% are achieved for 500-μm-cavity length diode lasers