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Abstract

An optical device directed at controlling wavelength transmission in a waveguide is disclosed. The basic device comprises a substrate containing an optical waveguide, a layer containing a grating, a variable refractive index layer and a set of electrodes for selectively applying a local temperature at points along the waveguide. The grating is disposed sufficiently close to the optical waveguide to be within the evanescent coupling field of the guided beam. The waveguide and variable index materials have significantly different thermo-optical coefficients of refractive index such that the differential thermal coefficient between the variable index material and the substrate can be used to vary the interaction strength between the guided wave and the grating. The grating may be formed as a phase grating within the variable index layer. Alternatively the grating and variable index medium may be in separate layers. The grating may be a surface relief grating backfilled with a variable index material. The grating may be configured as a chirped grating.

First Claim