Patent ID: 7366372

Claim:
An optical waveguide device for receiving light that has a first mode to be substantially guided and a second mode to be substantially unguided, the device comprising: an optically transmissive substrate having a length X and including first and second substantially opposite surfaces, an input end, and an output end; an optical waveguide region disposed within said substrate proximate said second surface and extending from said input end to said output end; a plurality of electrodes disposed on said first second at predetermined locations with respect to said waveguide region; and a spatial filter, comprising: a first optical barrier positioned in said substrate proximate said first surface at a distance of substantially (½)X from said input end; a second optical barrier positioned in said substrate proximate said first surface at a distance of substantially (¼)X from said input end; and a third optical barrier positioned in said substrate proximate said first surface at a distance of substantially (n/8)X from said input end, wherein n is an odd integer less than 8.