Author:
Fradin D. W.,Cheo P. K.,Peng S. T.,Tamir T.
Abstract
The efficient operation of thin-film devices requires that a substantial fraction of the input laser power be coupled through the waveguide and into a useful output beam. When high-quality waveguide structures are used, efficient coupling can be achieved with either a prism or a grating coupler. Work with free-standing (slab) waveguides used in an early model of a thin-film modulator for CO2 laser radiation (Ref. 1) has shown both that practical waveguide structures can have serious structural imperfections in the coupling regions and that device constraints may preclude the use of optimized waveguide and coupler designs.