Semiconductor Lasers: New Geometries and Spectral Properties

This thesis is an investigation into the spectral properties of two broad classes of semiconductor lasers. They are (1) broad-area lasers with non-planar mirrors, specifically, those with an unstable resonator configuration, and (2) coupled-cavity semiconductor lasers. The use of non-planar mirrors on broad-area lasers can substantially improve their properties. Chapter 2 focuses on the experimental realization of several unstable resonator semiconductor lasers, while chapter 3 presents a method of analyzing the modes of such a device. Coupling two cavities together can drastically alter the dynamic and spectral properties of a semiconductor laser. In chapter 4 we present experimental measurements and explain the properties of a laser consisting of two side-by-side coupled cavities. We then turn to the theoretical problem of analyzing the dynamic properties of multicavity lasers. In chapter 5, we derive a general expression for the dynamic response of a multielement laser. In the process, we develop a formalism for treating the dynamics of any semiconductor laser system with particular ease of application to single-mode multielement lasers. In chapter 6, we show that 2 or more cavities can lead to bistability and bimodality. The quantum fluctuation-induced noise properties of multicavity lasers are analyzed in chapter 7. In chapter 8, we return to the single-element laser and calculate non-quantum noise contributions--specifically, thermal and diffusion noise-- which give rise to a 1/f spectrum. In chapter 9 we present a new method of deriving multicavity rate equations and point out a shortcoming of the existing coupled-mode treatments.