Semiconductor Physics and Photonics

本文提出的研究工作包括三个部分：非线性材料的MBE生长，这些材料的半导体物理，以及使用这些材料的非线性器件。注意力将首先集中在GaAs的增长上。基础结构和装置如散、单。和多个量子阱样本，法布里。具有单片反射镜的佩罗标准子，以及非线性波导和量子点结构的起始材料。将研究样品的光学性质，特别强调激子以下光谱区域的线性和非线性光学性质。研究高激发下的吸收尾及其饱和度不仅是非常有趣的物理问题，而且有助于表征生长样品的质量，对优化装置的设计和操作至关重要。吸收尾、载流子寿命和偏振依赖性的带隙非线性将被研究作为量子阱宽度、生长条件和器件设计的函数。微光刻和各向异性刻蚀技术将用于制造非线性波导结构，如定向耦合器和马赫。曾德尔干涉仪，以及半导体标准子阵列。我们将研究如何控制载流子寿命，从而控制非线性器件的响应时间，并针对这两种情况设计器件。功率运行在相对较低的速度和超快的光交换。

The research effort proposed here consists of three parts: MBE growth of nonlinear materials, semiconductor physics of those materials, and nonlinear devices using those materials. Attention will be focused initially on growing GaAs.based structures and devices such as bulk, single. and multiple.quantum.well samples, Fabry.Perot etalons with monolithic mirrors, as well as starting material for nonlinear waveguides and quantum dot structures. The optical properties of the samples will be studied, with special emphasis on the linear and nonlinear optical properties in the spectral regions below the exciton. Studying the absorption tail and its saturation under high excitation is not only very interesting physics, but also helpful for characterizing the quality of the grown samples, and essential for optimum device design and operation. Absorption tail, carrier lifetime, and polarization dependence of the bandgap nonlinearities will be investigated as functions of quantum well widths, growth conditions, and device design. Microlithography and anisotropic etching techniques will be used, to fabricate nonlinear waveguide structures such as directional couplers and Mach.Zehnder interferometers, as well as arrays of semiconductor etalons. Methods to manipulate the carrier lifetime and, hence, the response time of the nonlinear devices will be investigated, and devices will be designed for both low.power operation at relatively low speed and forultrafast optical switching.