金属平面半导体量子阱微腔自发发射

应用微腔腔量子电动力学和半导体量子阱物理,讨论了平面半导体量子阱微腔的自发发射,得到了腔结构、量子阱参量和注入载流子下的微腔自发发射谱和载流子寿命.计算发现由于微腔和量子阱分别对光子和载流子的限制,平面微腔可以增进自发发射,具有很强单方向性。     

量子阱DBR微腔激光器中自发发射的控制

应用腔量子电动力学和量子阱物理,计算了量子阱DBR微腔激光器的自发发射谱.发现由于DBR微腔和量子阱分别对光子和载流子的限制,单方向的自发发射可以增进约三个量级,总的自发发射增强一个量级.     

量子阱DBR微腔激光器中自发发射的控制

应用腔量子电动力学和量子阱物理 ,计算了量子阱 DBR微腔激光器的自发发射谱 .发现由于 DBR微腔和量子阱分别对光子和载流子的限制 ,单方向的自发发射可以增进约三个量级 ,总的自发发射增强一个量级 .     

半导体激光器的微腔结构调制及其脉码在光纤中的传输

采用腔量子电动力学(QED)方法,定量讨论了平面结构微腔半导体激光器的自发发射特征物理量随腔结构的变化规律.在微腔半导体激光器自发发射因子调制、自发发射寿命调制以及一些实验依据的基础上,提出了微腔结构调制方法.数值模拟了其脉码在光纤中的传输图形.结果表明,微腔结构调制方法在提高脉码比特率方面优于同参数下的电流调制方法.     

半导体激光器的微腔结构调制及其脉码在光纤中的传输

采用腔量子电动力学(QED)方法,定量讨论了平面结构微腔半导体激光器的自发发射特征物理量随腔结构的变化规律.在微腔半导体激光器自发发射因子调制、自发发射寿命调制以及一些实验依据的基础上,提出了微腔结构调制方法.数值模拟了其脉码在光纤中的传输图形.结果表明,微腔结构调制方法在提高脉码比特率方面优于同参数下的电流调制方法.     

光泵浦垂直外腔面发射激光器的结构优化设计

实验中发现,传统结构的光泵浦垂直外腔面发射半导体激光器,随着泵浦功率密度的增加,器件的温升现象严重.这是由于传统结构中,势垒和量子阱间小的带隙差造成的.为了解决温升问题,采用PICS3D软件对传统结构进行优化设计.在吸收层中引入对泵浦光和激射光透明的AIGaAs层,提高对量子阱中的载流子的限制作用.计算结果表明,在增益和自发发射特性上,优化后的结构都有了很大提高.     

FP腔半导体激光器的腔内损耗和准费米能级差的测量

利用一种拟合方法测量FP腔半导体激光器的腔内损耗和准费米能级差.从放大的自发发射谱,利用Cassidy方法得到用于拟合过程的增益谱和单程放大的自发发射谱.利用上述方法,测出的1550nm InGaAsP量子阱脊型波导结构激光器的腔内损耗大约为24cm-1.     

FP腔半导体激光器的腔内损耗和准费米能级差的测量

利用一种拟合方法测量FP腔半导体激光器的腔内损耗和准费米能级差.从放大的自发发射谱,利用Cassidy方法得到用于拟合过程的增益谱和单程放大的自发发射谱.利用上述方法,测出的15 5 0nmInGaAsP量子阱脊型波导结构激光器的腔内损耗大约为2 4cm-1.     

半导体微腔中电偶极子的自发发射

由于反射电场的影响，电偶极子在微腔中的自发发射速度不同于自由空间中的自发发射速度。本文采用镜像法计算了理想平面微腔、金属平面镜组成的半导体微腔和由分布布喇格反射镜（DBR）作为谐振腔的垂直发射激光器（VCSEL）中电偶极子的自发发射速率。计算结果表明：由于微腔的调制作用，在某些情况下电偶极子自发发射速率增加，在一定腔长下电偶极子自发发射速度被抑制。     

降低VCSELs激射阈值途径的理论研究

针对量子阱有源层的结构特点，考虑增益和载流子浓度呈对数关系，建立量子陆垂直腔面发射半导体激光器（VCSEL）的速率方程，导出了阈值电流密度的解析表达式，运用MATLAB软件中Simulink可视化仿真系统对理论计算进行模拟仿真，研究了降低VCSEL激射阈值的3个基本途径；有源层选用量子阱实现微腔结构，腔面采取多层介质反射膜提高光腔反射率R：改进外延生长技术在降低各种损耗。     

半导体微腔激光器中的自发辐射耦合增强效应

针对半导体微腔激光器的结构特点,以及腔量子电动力学中自发辐射增强效应,采用光增益与载流子密度的对数关系,引入增益饱和项和非辐射复合项的贡献,指出即便是对于理想的封闭微腔,由于非辐射衰减速率的影响,光输出并不随泵浦线性变化。结合频谱和相图分析,给出了自发辐射耦合因子与微腔激光器的辐射阈值、开关延迟时间、驰豫振荡频率和光输出等参量关系的仿真结果,这对于微腔激光器的理论研究和优化器件结构有所裨益。     

垂直腔半导体光放大器频率响应特性研究

从速率方程出发,利用小信号分析方法对垂直腔半导体光放大器(VCSOA)的频率响应特性进行了研究.在考虑了量子阱材料中的增益和载流子浓度之间的对数关系后,得到了VCSOA的峰值响应频率以及3 dB频率响应带宽的解析表达式.结果表明,VCSOA的频率响应特性受抽运光强度、输入光功率以及自发辐射因子的影响.     

Controlled exciton spontaneous emission inoptical-microcavity-embedded quantum wells

A theory for polaritons and intrinsic spontaneous emission by excitons in quantum wells embedded in planar optical microcavities is presented. Excitons in ideal quantum wells are extended states, and the resulting spatial coherence leads to spontaneous-emission characteristics different from those for point dipoles in a planar cavity. It is pointed out that the quality factor Q of a planar cavity is typically strongly dependent upon the in-plane wave vector k&oarr; _∥ of excitation; in particular, we demonstrate that both strongly enhanced emission (low Q) as well as strongly inhibited emission accompanied by vacuum-field Rabi oscillations (high Q) occur in the same cavity at different k&oarr;_∥. Free-and localized-exciton radiative decay and radiation dynamics associated with confined and radiation modes of the optical field are considered, as well as the temperature dependence of the emission as measured in time-resolved photoluminescence spectroscopy. Other results obtained are a two-dimensional form of the longitudinal-transverse splitting for and dispersion of exciton polaritons in the presence of a cavity     

微腔与腔量子电动力学研究进展

光学微腔中原子之自发辐射与自由空间中原子的自发辐射有着重要的不同。微腔能够控制腔内原子的自发辐射，使自发辐射得到抑制或增强，并有可能使自发辐射成为一个可逆过程。由此发展起来的腔量子电动力学能够阐述腔场与原子的相互作用。本文简要介绍了这一研究领域的背景和进展，同时介绍了微腔的重要应用一无阈值激光器。     

多量子阱垂直腔面发射半导体激光器的速率方程分析

依据多量子阱垂直腔面发射半导体激光器（ＶＣＳＥＬＳ）的结构特点,并考虑到腔量子电动力学中自发辐射增强效应,建立了多量子阱ＶＣＳＥＬＳ的速率方程,并给出了其方程的严格解析解,在此基础之上,讨论了ＶＣＳＥＬＳ的稳态特性,并与普通开腔和三维封闭腔中的结果进行了比较,给出了Ｖ     

Wide-range tunable semiconductor lasers using asymmetric dualquantum wells

Using asymmetric dual quantum wells for the laser material, the semiconductor lasers are broadly tunable. In a grating coupled ring cavity, the semiconductor laser is continuously tunable from 766 to 856 nm using a 400-μm semiconductor laser amplifier in the cavity. This letter also demonstrates that the grating coupled ring cavity could well eliminate the amplified stimulated emission noise and about 40-dB amplified spontaneous emission (ASE) suppression ratio is obtained over the entire tuning range     

Capture of charge carriers and output power of a quantum well laser

The effect of noninstantaneous carrier capture by a nanoscale active region on the power characteristics of a semiconductor laser is studied. A laser structure based on a single quantum well is considered. It is shown that delayed carrier capture by the quantum well results in a decrease in the internal differential quantum efficiency and sublinearity of the light-current characteristic of the laser. The main parameter of the developed theoretical model is the velocity of carrier capture from the bulk (waveguide) region to the two-dimensional region (quantum well). The effect of the capture velocity on the dependence of the following laser characteristics on the pump current density is studied: the output optical power, internal quantum efficiency of stimulated emission, current of stimulated recombination in the quantum well, current of spontaneous recombination in the optical confinement layer, and carrier concentration in the optical confinement layer. A decrease in the carrier capture velocity results in a larger sublinearity of the light-current characteristic, which results from an increase in the injection current fraction expended to parasitic spontaneous recombination in the optical confinement layer and, hence, a decrease in the injection current fraction expended to stimulated recombination in the quantum well. A comparison of calculated and experimental light-current characteristics for a structure considered as an example shows that good agreement between them (up to a very high injection current density of 45 kA/cm²) is attained at a capture velocity of 2 × 10⁶ cm/s. The results of this study can be used to optimize quantum well lasers for generating high optical powers.     

Microcavity effects in an external-cavity surface-emitting laser

Microcavity-induced lasing threshold reduction and modulation of the spontaneous emission coherence length with cavity length in an external-cavity resonant-periodic-gain, surface-emitting laser is reported. In contrast to comparing different epitaxial growths, external-cavity operation allows changing the cavity length without affecting material properties as well as arbitrarily long resonator lengths. The transition to the macrocavity domain is observed by extending the cavity length beyond the spontaneous emission coherence length. The maximum change in the spontaneous emission rate induced by the cavity QED effect in the presence of resonant periodic gain is calculated. As expected, for cavities longer than several wavelengths, microcavity Fabry-Perot resonance effects dominate over cavity QED in determining the cavity-normal spontaneous emission power and coherence length. A simple model of the cavity-normal spontaneous emission coherence length and spontaneous emission power emitted from a Gaussian source placed in an ideal Fabry-Perot cavity is consistent with our observations     

Lifetime broadening in GaAs-AlGaAs quantum well lasers

Experimental observations of spontaneous emission spectra from GaAs-AlGaAs quantum well lasers shown that spectral broadening should be included in any realistic model of laser performance. A model of the lifetime broadening due to intraband Auger processes of the Landsberg type is described and developed for the case of electron-electron scattering in a 2-D system. The model is applied to the calculation of gain and spontaneous emission spectra and gain-current relationships in short-wavelength GaAs-AlGaAs quantum well lasers, and the results are compared with those obtained using both a fixed intraband scattering time and one that varies as n^-1/2, where n is the volume injected carrier density