OPTICAL WAVE-GUIDE FAN-OUT ELEMENTS USING DISLOCATED GRATINGS FOR BOTH OUTCOUPLING AND PHASE-SHIFTING

A novel scheme is proposed and experimentally demonstrated for the con struction of an optical waveguide fanout element. The device is compos ed of an array of rectangular elements, each containing a dislocated g rating, on an optical waveguide, The functions of the gratings are two fold: outcoupling the guided wave and introducing phase shifts. Such a waveguide fan-out device has been fabricated on an AlGaAs-GaAs wavegu ide. The uniformity error and the diffraction efficiency were measured to be similar to 11% and similar to 60%, respectively,