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.     

半导体激光器微腔结构调制的脉码在光纤中的传输

对于平面结构微腔半导体激光器的微腔结构调制，数值模拟了其输出二进制脉码在光纤中的传输眼图，给出了双态对应的微腔结构参数与脉码在线性光纤中无误码传输最大距离的数值对应关系。     

微腔激光器数码调制及其光纤传输的研究

从微腔半导体激光器速率方程出发，分析讨论了微腔激光器的脉码调制特性，发现微腔具有较规则的脉冲响应，可以减少误码率；自发发射因子为０．１的微腔，具有脉码率高达５０Ｇｂｉｔ／ｓ良好的调制眼图，微腔激光器在光互联中将有广泛的应用前景。模拟了以微腔激光器为光源的光纤通信系统，给出脉码率为１０Ｇｂｉｔ／ｓ传输不同距离的接收眼图，证明能够实现６０ｋｍ的传输。     

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。     

微腔半导体激光器的结模型

本文提出微腔半导体激光器的站模型,并分析讨论了自发发射因子β＝１的微腔半导体激光器的一些稳态和瞬态特性．     

微腔半导体激光器的站模型

本文提出微腔半导体激光器的站模型,并分析讨论了自发发射因子β＝１的微腔半导体激光器的一些稳态和瞬态特性。     

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。     

平面微腔半导体激光器的横模控制

腔的维度只有一个波长量级的微腔半导体激光器的研究是近年来激光物理学、量子光学以及光电子学领域非常活跃的研究课题。理论预言，由于腔量子电动力学性质的影响，其自发发射效率增强，因而有可能实现无阈值工作，其高频调制带宽可能高过100GHz．到目前为止，对于微腔半导体激光器研究最多的是由两组多层介质膜组成的一个波长间隔的法布里-珀罗腔结构的垂直腔面发射半导体激光器。近年来对这种激光器的研究取得了很大的进展．然而仍存在的一个很大的问题是在注入电流比较大时，激光器会输出高阶横模。本文从实验与理论两方面研究了其高阶…     

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.     

Noise-driven rate equation analysis of quantum-well, microcavity lasers

Noise-driven rate equations are used in modeling microcavity, quantum-well, semiconductor lasers. Results for different cavity designs are compared. Particular attention is paid to threshold and noise characteristics. Using attainable dimensions it is seen that threshold current is reduced, relaxation modulation bandwidth is increased and turn-on delay is shortened as previously predicted for devices with enhanced spontaneous emission. In addition, it is shown that the device tends to lose its coherence as the microcavity design is approached, and the microcavity loses its noise advantage as the bandwidth is increased (when external modulation is considered) because of the lack of roll-off in the 100 GHz spectrum presented.<>     

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。     

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     

Steady-state and transient characteristics of microcavitysurface-emitting lasers with compressively strained quantum-well activeregions

In conventional semiconductor lasers, the dimensions of the optical cavity greatly exceed the photon wavelength, and the photon density of states forms a continuum since it is essentially that of a bulk system. On the other hand, in an ideal laser, one would like to have a single optical mode coincident with the maximum in the gain spectrum of the active medium. We show that substantial density-of-states quantization and enhancement of the fraction of photons spontaneously emitted into the lasing mode can be obtained by reducing the lateral width of the surface-emitting laser. For emission at λ=0.954 μm, the threshold current density can be drastically reduced by increasing the coupling factor to a few percent. For a cavity structure width of 0.3 μm, the threshold current density is 50 A/cm², compared with 250 A/cm² for the 0.6-μm cavity. At lower still lateral widths, the cavity loses its vertical character, and confinement of the lateral optical mode rapidly deteriorates. The large-signal response of microcavity lasers is slightly improved primarily due to elimination of mode competition in intrinsically single-mode microcavities, with relaxation times close to 1 ns. The enhancement of the spontaneous emission coupling factor results in an increase of the relaxation oscillation frequency and improvement in the standard small-signal response of microcavity lasers. For J=10J_th, the -3 dB modulation frequency exceeds 40 GHz. Since low threshold current densities may be achieved in microcavity lasers, the gains in small-signal performance are primarily extrinsic, i.e., higher modulation bandwidths ace accessible for the same injection     

Analysis of semiconductor microcavity lasers using rate equations

The rate equations for a microcavity semiconductor laser are solved and the steady-state behavior of the laser and some of its dynamic characteristics are investigated. It is shown that by manipulating the mode density and the spontaneous decay rates of the cavity modes, the threshold gain can be decreased and the modulation speed can be improved. However, in order to fully exploit the possibilities which the modification of the spontaneous decay opens up, the active material volume in the cavity must be smaller than a certain value. Threshold current using different definitions, population inversion factor, L-I curves, linewidth, and modulation response are discussed     

半导体微腔激光器瞬态响应及调制特性分析

针对半导体微腔激光器的结构特点,考虑到腔量子电动力学中自发辐射增强效应,采用传统速率方程的表示形式,建立了微腔激光器的速率方程,着重讨论了微腔激光器的瞬态响应及调制特性,给出了其动态特性的仿真结果,分析了自发辐射因子、注入电流和腔长对微腔激光器的激射阈值、延迟时间、驰豫振荡频率和光输出等参量的影响,从而为改善微腔激光器的高频调制特性和优化器件结构提供了理论依据。     

Variation of intensity noise and frequency noise with thespontaneous emission factor in semiconductor lasers

The intensity noise level and the spectral line-width of semiconductor injection lasers are theoretically analyzed. Approximated but simple forms representing these characteristics are found to give criteria for various types and sizes of cavity, including microcavity lasers. The noise and the line-width are reduced by operation with high injection current or high optical power in general. For operation at a low-power level in the microcavity laser, increase of the spontaneous emission factor as well as reduction of the threshold current level and the threshold gain level are important to get a low noise level and narrow line-width     

Spontaneous emission control in semiconductor microcavities withmetallic or Bragg mirrors

We present a systematic study of the modification of the spontaneous emission of a point dipole in a planar semiconductor microcavity, bounded by different types of mirrors. Numerical evaluations of the spontaneous emission rate indicate that semiconductor cavities bounded by Bragg mirrors display only a weak modification of spontaneous emission, while significant enhancement and inhibition of spontaneous emission should be observed in cavities bounded by metallic mirrors