Design, fabrication, and performance of preferential-order volume grating waveguide couplers

Both a nonfocusing and a focusing preferential-order volume grating wavegui de coupler were designed, fabricated, and tested. These volume grating coup lers are designed to outcouple a 633-nm wave guided in an adjacent polyimid e waveguide film. The slanted-fringe volume gratings are recorded holograph ically by the interference of two 364-nm waves. The dynamics of the hologra phic photopolymer HRF600X001 are investigated in relation to the interactio n vith the guided wave. The fabricated couplers exhibited a preferential co upling of 98%, a spatial coupling rate of 3.6 mm(-1), and a coupling effici ency of 95%. The focusing grating coupler focused the outcoupled beam to a focal line with a full width at half-maximum of 10.49 mu m located 25 mm ab ove the grating. (C) 2000 Optical Society of America.