Abstract

A wide variety of integrated optics devices require some variation in the effective index of a waveguide. This can be accomplished by locally varying either the waveguide's thickness (i.e., a lenslet) or its index of refraction. We are investigating methods by which very large index changes might be locally induced in certain thin films either by masked ion bombardment during deposition or by a laser-driven chemical reaction after deposition. These processes could be useful for the direct fabrication of gratings and channel waveguides, as well as improving the performance of other integrated optic components such as focusing grating couplers (FGCs). An appropriate index profile under an FGC would allow correction of aberrations introduced by a small mismatch between the FGC design wavelength and the actual operating wavelength. For some designs, index changes of 0.3–0.5 or more are required, which is beyond the capabilities of conventional doping techniques. In certain materials systems, the compositional changes caused by a chemical reaction or ion bombardment might lead to sufficiently large index changes without greatly disturbing the film's thickness.

© 1989 Optical Society of America