(A) study on semiconductor laser diode arrays

Abstract

Both passive and active array analyses have been used to study the index-guided as well as gain-guided laser diode arrays. Some important facts have been found from these numerical results. And multi-section laser diode arrays with three emitters have been proposed to obtain a single-lobe beam in the far-field pattern. This dissertation work can be classified into three parts and is summarized as follows: \begin{center} [Passive array analysis on the six-channel index-guided arrays] \end{center} I have investigated in detail the dependence of supermode discrimination characteristics and radiation angles of laser arrays on channel widths and spacings. The tendency of changes in the supermode discrimination characteristic caused by channel-chirping is quite different from that by spacing-chirping. Therefore the desired supermode discrimination characteristic compromised with the radiation angle can be obtained by chirping both channels and spacings properly. It has been found that the asymmetrically V channel-chirped array has both a smaller radiation angle and better supermode discrimination characteristic than the uniform array. By selecting a proper gain profile which can be achieved, for example, by using separate laser contacts, we can make the fundamental supermode dominant and moreover obtain the enhanced supermode discrimination characteristic for the index-guided arrays. Some approaches for obtaining a enhanced modal stability have been studied, comparing their supermode discrimination characteristics and radiation angles one another. \begin{center} [Active array analysis on the arrays with three emitters] \end{center} For pure gain-guiding arrays (assumed antiguiding parameter R=0), the transition from single-lobe to twin-lobe far-field appears to occur at about S (center to center spacing between two emitters)=8 m. But for the actual gain-guided arrays (R=3), the transition appears to occur at about S=6 m which is smaller than that for the R=0 case. Th...