An optimization procedure for the selection of diode laser facet coatings

The relationship between the facet reflector properties and the steady-state power-current characteristics of diode lasers is analyzed. A general procedure is developed for calculating the facet reflectance values that optimize the electrical-to-optical power conversion efficiency of a diode laser emitting a specified value of optical power. Numerical examples are presented which apply this technique to the selection of facet coatings for a typical diode laser. The diode laser with optimized facet reflectances is shown to have lower internal power dissipation than devices with uncoated or half-wave coated facets. The properties of Al2O3/Si multilayer facet coatings are investigated, with special attention given to the effects produced by optical absorption in the amorphous silicon layers.