Semiconductor Laser Diode Arrays by MOCVD (Metalorganic Chemical Vapor Deposition)

The purpose of this program is to develop the metalorganic chemical vapor deposition MOCVD epitaxial growth process for semiconductor heterostructure laser diode arrays. These laser diode arrays are intended to be used as an optical pump for solid state yttrium aluminum garnet YAG lasers. In particular, linear uniform arrays having high output power, high efficiency, low laser threshold current density and precisely controlled emission wavelength are required. There are three technical problems associated with this task. The first problem is development of individual laser diode device structures which satisfy the requirements for efficiency, threshold and wavelength control and are suitable for incorporation into laser arrays. There are a number of possible structures varying in complexity from conventional five-layer double heterostructures having alloy AlGaAs active regions to very sophisticated quantum well heterostructures QWH. The second problem is an analytical study of the waveguide properties of multi-element laser arrays. Simple arrays of conventional double heterostructure laser diodes have been studied but extension of this work to other laser diode geometries is non-trivial. Preliminary and optimum geometries for the individual structures and the photomasks used for device processing require some modeling of the optical properties of these arrays. The third problem, and the major point of this entire program, is experimental development of suitably designed individual laser diode structures in a well modeled multi-element array.