INVESTIGATION OF OPTICAL LOSSES IN PHOTOELASTIC AND RIDGE WAVE-GUIDESIN GAAS-ALGAAS HETEROSTRUCTURES

Two approaches have been used to fabricate stable photoelastic wavegui des with planarized surfaces on GaAs-AlGaAs heterostructures. The firs t approach uses tensile Ni3GaAs stressors formed by metal-semiconducto r reactions, The second approach uses inert, refractory and compressiv e stressors, such as RF sputtered W and RF co-sputtered WNi films, For comparison purposes, ridge waveguides have also been fabricated using the same heterostructure by a dry etching technique, Optical losses o f photoelastic waveguides, measured by Fabry-Perot (FP) method at a wa velength of 1.53 mu m, are comparable to or better than those of the r idge waveguides, Material loss appears to be the primary loss mechanis m in both photoelastic and ridge waveguides, These results indicate th at the photoelastic waveguide processing technique reported in this st udy is a promising alternative to commonly used dry etching techniques for planarization.