Photopolymer-based diffractive and MMI waveguide couplers

Diffractive and multimode-interference waveguide couplers constructed from photopolymer materials are presented. Two-material grating-in-the-waveguide optical interconnects are fabricated and tested with respect to waveguide propagation loss and grating out-coupling. Waveguide/grating interconnects have been constructed with both index-defined and air-clad waveguide channel regions, where air-clad channels exhibit measured propagation losses of α_wg=0.47-3 dB/cm. Measurements of output coupling coefficients of volume grating couplers terminating various waveguide channels range from α_g=1.4-5.3 mm^-1. A 1 × 4 photopolymer-based multimode-interference power-splitting coupler fabricated and tested for the provision of in-plane optical coupling is found to demonstrate 0.3-0.6-dB output power uniformity.