PROCESS FOR FABRICATION AND INDEPENDENT TUNING OF MULTIPLE INTEGRATED OPTICAL DIRECTIONAL COUPLERS ON A SINGLE SUBSTRATE

摘要

A method of fabricating an optical device incorporates two different techniques for formation of different structures of the device on the same substrate. Individual processes such as Titanium indiffusion and annealed proton exchange in LiNb03 require significantly different temperature ranges for comparable waveguide formation. The present method combines these processes and allows for temperature tuning of the optical parameters of passive and active components, for instance coupling lengths of directional couplers, associated with one section of the device without altering the optical parameters of similar components in the other sections. The process improves yield for devices which employ more than one precisely fabricated optical directional coupler by creating an extra degree of process freedom. The method includes the steps of diffusing a first material at a first temperature into a first portion of the substrate to define a first guide for the optical beam. The first material diffuses significantly into the substrate only at temperature comparable to, or greater than the first temperature. The method also includes the step of diffusing a second material into a second portion of the substrate at a second temperature to define a second guide for the optical beam. The second temperature is substantially less than the first temperature such that approximately none of the first material in the substrate continues to diffuse while the second material diffuses into the substrate.