Method for altering the temperature dependence of optical waveguides

Abstract

In accordance with the invention glass waveguide devices are provided with enhanced temperature stability by incorporating within appropriate lengths of the waveguides a transparent compensating material having a refractive index variation with temperature that differs substantially from that of the waveguide. The compensating material can be a non-glass material, such as a liquid, driven into the glass by heat and pressure. In a preferred embodiment, D.sub.2 O is incorporated into waveguides for optical communications. The D.sub.2 O is transparent to the preferred communications wavelengths centered at about 1.55 .mu.m and has a dn/dT opposite in polarity to the dn/dT of glass. The resulting structure exhibits enhanced temperature stability with reduced magnitude of dn/dT. The technique is particularly useful in devices based on interference between multiple waveguides, as it is not necessary to reduce dn/dT to zero in the respective waveguides. It suffices to compensate the differences. Such compensation can be achieved by compensating materials having dn/dT of either the same polarity as the dn/dT of the waveguides or the opposite polarity. Preferred embodiments include routers, Fourier filters and Bragg filters. In single waveguide devices such as gratings, compensating materials of opposite polarity can substantially enhance the temperature stability.