Carrier and photon analyses of photonic microlasers by two-dimensional rate equations

In photonic crystal (PC) microlasers with point defect cavities, effective carriers are reduced by the leakage to outside of the defect, surface recombination, spatial carrier hole burning, and Auger recombination. To estimate these effects, we calculated carrier and photon behavior by solving two-dimensional rate equations in space and time domains. The result clearly shows these effects and their dependence on cavity structure, pump area, and so on. Compared with that for the microdisk laser, higher threshold values are estimated for PC microlasers. However, a comparably low threshold density and a high efficiency are expected for the quasi-periodic PC microlaser, because the hole burning by the whispering gallery mode of this cavity suppresses the carrier leakage.     

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     

Edge-emitting semiconductor microlasers with ultrashort-cavity anddry-etched high-reflectivity photonic microstructure mirrors

We demonstrate very compact low-threshold edge-emitting semiconductor lasers operating at a wavelength of 980 nm, in which periodic microstructure mirrors have been formed at both cavity ends by deep reactive ion etching. From a threshold analysis, we determined reflectivities of ~95% for the seven-period back reflector and ~80% for the three-period front mirror. Lasing has been achieved from 20-μm-long and 8-μm-wide devices exhibiting a current threshold of 7 mA. These are among the shortest in-plane electrically pumped lasers demonstrated so far. State-of-the-art electron beam lithography (EEL) and high-aspect ratio reactive ion etching (RIE) have been used for device fabrication     

包括增益压缩因子的半导体激光器行波速率方程

对包含增益压缩因子的半导体激光器（ＬＤ）的稳态速率方程组进行了求解，得到了隐函数形式的解析解，并以此讨论了增益压缩因子对某些ＬＤ稳态特性的影响。     

A reassessment of standard rate equations for low facetreflectivity semiconductor lasers using traveling wave rate equations

A set of traveling wave equations, which are a simple extension of the common rate equations, is used to study the effect of longitudinal gain saturation in Fabry-Perot semiconductor lasers. Analytical solutions are derived which are valid for both low and high Q cavities. A comparison is made to a theory with no spatial dependence. The maximum longitudinal carrier density deviation from the threshold value under lasing conditions is calculated for arbitrary facet reflectivities. It is shown that this deviation leads to linear equations for the emitted output power when compared to a standard rate equation theory. Improved designs for semiconductor lasers are suggested from this analysis     

Stability of semiconductor injection lasers in the framework of the model described by rate equations

The stability of semiconductor injection lasers is studied on the basis of the analysis of the first Lyapunov exponent and the characteristic parameters of the laser rate equations.     

半导体激光器调制响应的速率方程小信号近似法研究

速率方程是研究半导体激光器瞬态过程的理论工具。为了能对实际中各种调制响应进行分析,采用小信号近似法求解了在任意调制信号下半导体激光器的速率方程。得到了任意调制信号下半导体激光器的速率方程的实值解析解,并根据得出的实值解析解分析了半导体激光器的一些调制响应特性,给出了一个调制信号为矩形脉冲电流的具体实例。最后研究并得出了小信号近似法准确的严格条件。根据一些半导体激光器的实际参数,给出了该条件在某些情况下的近似表达。     

Analysis and numerical simulation of eigenmode characteristics forsemiconductor lasers with an equilateral triangle micro-resonator

The eigenmodes confined in the equilateral triangle resonator (ETR) are analyzed by deriving the eigenvalues and the mode field distributions and by the finite difference time domain (FDTD) technique. The analytical results show that the one-period-length for the mode light rays inside the ETR is the perimeter of the ETR, and the number of transverse modes is limited by the condition of total internal reflection. In addition, the sum of the longitudinal mode index and the transverse mode index should be an even number, which limits the number of confined modes again. Based on the FDTD technique and the Pade approximation, we calculate the mode resonant frequencies and the quality factors from the local maximum and the width of the spectral distribution of the intensity. The numerical results of mode frequencies agree very well with the analytical results, and the quality factor of the fundamental mode is usually higher than that of the higher order transverse modes. The results show that the ETR is suitable to realize single-mode operation as semiconductor microcavity lasers     

Analysis of equilateral three-core fibers by circular harmonicsexpansion method

The modal characteristics of equilateral three-core fibers are analyzed using a rigorous method based on circular harmonics expansion. The polarization patterns of the vector modes are obtained, and the mode splitting characteristics of these modes are examined. The results confirm the validity of a perturbation analysis of the same problem by A.J. Stevenson and J.D. Love (1987)     

Mode characteristics of semiconductor equilateral triangle microcavities with side length of 5-20 /spl mu/m

Semiconductor equilateral triangle microresonators (ETRs) with side length of 5, 10, and 20 /spl mu/m are fabricated by the two-step inductively coupled plasma (ICP) etching technique. The mode properties of fabricated InGaAsP ETRs are investigated experimentally by photoluminescence (PL) with the pumping source of a 980-nm semiconductor laser and distinct peaks are observed in the measured PL spectra. The wavelength spacings of the distinct peaks agree very well with the theoretical longitudinal mode intervals of the fundamental transverse modes in the ETRs, which verifies that the distinct peaks are corresponding to the enhancement of resonant modes. The mode quality factors are calculated from the width of the resonant peaks of the PL spectra, which are about 100 for the ETR with side length of 20 /spl mu/m.     

Two formulations of semiconductor transport equations

Transport equations for semiconductors can be written with the diffusion term as qD₁?_n or as q?(D₂n), where D₁ and D₂ are diffusion coefficients. In a recent note in this journal the issues arising from this ambiguity were clarified and the possibility of a more general treatment, valid for arbitrary densities of states and current carriers, was announced. The details are given in this paper which includes magnetic field effects and covers also thermal conductivity, thermoelectric power and Soret coefficients in the two formulations. A special effort is made to develop a consistent macroscopic scheme of equations separately from their microscopic interpretations. A number of new equations and convenient connecting formulae between the two formulations are given; for example four general Einstein relations are found: for the electric and heat currents in the D₁- and the D₂-formulations.     

一种等边三角形缝隙环宽带天线的设计

提出一种带有枝节槽的等边三角形缝隙环结构宽带天线.基于多模谐振原理,将天线馈源设置在三角形缝隙环中非对称位置,同时在三角形缝隙环上对称添加2个枝节槽以便形成更多谐振回路,从而激励出多个模式,得到多模谐振,提高缝隙天线带宽.仿真和实测结果基本一致.实测所设计的天线的阻抗带宽为2.11～3.32 GHz,|S11|<-10...     

Numerical solution of the semiconductor transport equations with current boundary conditions

The semiconductor transport equations are solved by a hybrid finite-element method with current specified as a boundary condition at device contacts. Single carrier or bipolar devices of arbitrary shape, operating under transient or steady-state conditions, can be simulated with current sources or simple circuit elements connected to device terminals. This paper describes the numerical technique and device applications.     

利用速率方程分析光纤激光器相干耦合系统的尝试

尝试采用稳态速率方程,分析了由一个光纤耦合器连接起来的、两个掺Er光纤激光器组成的相干耦合系统.考虑到设置在光纤耦合器的一个输出端口的公共反射镜还担负着实施两个激光器间的相互注入的功能,利用光纤耦合器的变换矩阵以及光场相干叠加的要求,可以确定激光器速率方程组满足的边界条件.在进行合理的近似处理后,把速率方程组转化为代数方程组.利用这些结果分析了系统的一些特性,比如耦合器的分光比和不同泵浦功率对输出功率的影响等.     

Analysis of the spontaneous emission rate of multiple-phase-shift distributed feedback semiconductor lasers

A general expression for the spontaneous emission rate of multiple-phase-shift DFB semiconductor lasers is given using the transfer matrix based on the Green's function method. The spontaneous emission rate for coupled phase-shift DFB lasers is calculated.<>     

Laser rate equations with phase sensitive interactions

A set of multimode rate equations which couple the complex fields to the mean number of amplifiers is derived. It is shown that in the case of semiconductor lasers, phase-sensitive interactions must be retained. The resulting equations are studied and bifurcation diagrams are presented that display the steady, periodic, and quasiperiodic solutions     

Reformulation of basic semiconductor transport equations—II

The semiconductor transport equations are reformulated in terms of two new variables one of which measures the departure of the PN product from its equilibrium value and the other the space charge. The electric field is eliminated and the total current becomes the basic independent variable. Boundary conditions are found for these new variables which, being based on thermionic emission at the metal-semiconductor contact, are applicable under all circumstances where tunnelling is insignificant. Using these boundary conditions the terminal voltage is shown to divide into an internal ohmic term, a term dependent on the variation of the PN product and terms dependent on the conditions at the metal semiconductor contacts.     

Failure rate prediction of optical semiconductor devices

The failure modes of optical semiconductor devices are classified into wear-out and random failures. The failure rate estimation methods are also presented for each mode using lognormal and exponential distributions. Moreover, based on the life-test data of InGaAsP/InP DH LDs and Ge-APDs as concrete examples, statistical analysis is carried out for the wear-out mode. This analysis suggests some problems underlying the high-reliability assurance of these devices. Finally, the testing scale and conditions are statistically investigated to confirm the random failure rates of 300 FITs for LDs and 3 FITs for Ge-APDs assuming the temperature dependency of the failure rate obeys the Arrhenius law.     

Analysis of semiconductor laser arrays with high-intensityuniformity

It is shown that an array with a highly uniform intensity distribution can be constructed. This decreases the spatial hole burning and makes stable, high-power operation easier. An estimate of the remaining spatial hole burning is derived and it is shown how its effects can be compensated for. It is considered that laser arrays which operate in the fundamental mode even at high-power levels can be designed