DIODE-LASER-TO-WAVE-GUIDE BUTT COUPLING

A diode-laser-to-waveguide butt-coupling model is described. The model takes into consideration the Fabry-Perot reflection and transmission of the etalon formed by the laser front facet and the waveguide entran ce facet. The model predicts coupling efficiency and the coupled-power fluctuations that occur versus the separation between the laser and t he waveguide. Calculations performed for Fabry-Perot-laser-to-KTP wave guide coupling show that the transverse and the angular alignment tole rances of the waveguide can be increased when the waveguide entrance f acet is antireflection coated. The longitudinal alignment tolerance of the waveguide can be increased by use of an index-matching gel betwee n the laser and the waveguide.