Title

Coupled wave analysis of two-dimensional second order surface-emitting distributed feedback lasers

Author

Yangfei Shen

Date of Award

2016

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics and Photonics

Advisor/Chair

Advisor: Andrew Sarangan

Abstract

A distributed feedback laser (DFB) is a type of semiconductor laser where the cavity is periodically structured as a diffraction grating. This allows the same grating region to act as a resonator, out-coupler and the gain region simultaneously. While conventional DFB lasers emit light along its edges, by modifying the grating structure, it is possible to make the output appear from the top surface. This is known as the surface-emitting DFB laser. This thesis will discuss the case in which a two-dimensional grating (which consists of a 2D grid of holes or pillars) etched into the top cladding surface of the waveguide. The thesis consists of four main parts. For the first part, we give the background principles and the coupled wave equations with radiation modes. In the second part, we derive the equations for a waveguide that utilizes a grating strip for guidance. The effective index of this guide is then used in the 2D DFB crossed grating structure. The third part begins with calculations of a particular GaAs:GaAlAs waveguide geometry with a grating. We present the fundamental resonant modes by utilizing the numerical shooting method. Then, the matrix solution method is applied in the calculation of the higher order guided and radiation modes. In the last part, we solve the transcendental equations for the eigenvalues to get the threshold gain and near field radiation pattern from the DFB surface.

Keywords

Semiconductor lasers, Diffraction gratings, Engineering, Optics, Two-Dimension, DFB, Second-Order, Grating, Near Field, Threshold Gain

Rights Statement

Copyright 2016, author

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