Modification of the beam profile from semiconductor lasers by spatial manipulation of an optical feedback field

Abstract

Summary form only given. We report on the spatial beam characteristics of a standard, low power index-guided semiconductor laser (Hitachi HL8314). The results of three studies, including the effect of (i) focusing, (ii) tilting and (iii) aperturing the optical feedback field will be presented along with modelling using Gaussian beam propagation methods. All of the spatial beam profiles show that the beam profile is determined by interference of the emitted and optical feedback fields at the output facet of the laser diode. The importance of interference in determining the spatial beam profile has been shown before but here we demonstrate definitively that it is interference between the optical feedback field and the emitted field, rather than ghost reflection off intracavity optics, that determines the detailed profile. Results on how the output power of the system of laser diode with optical feedback varies as the spatial feedback field is tailored will also be presented.