Large fanout optical interconnects using thick holographic gratings and substrate wavepropagation

Substrate wave propagation and Bragg diffraction by multiplexed holographic gratings have been used to demonstrate a new l-to-30 fanout optical interconnect having an overall diffraction efficiency of 87.8% at514.5 nm and an individual channel efficiency of ˜ 3.0 ± 0.8%. The device configuration utilizes the largemultiplexing capability of dichromated gelatin polymer films and substrate total internal reflection torealize large channel fanouts within the plane of a soda-lime glass substrate. A simplified theoreticalformulation is presented to treat the corresponding three-dimensional holographic diffraction problem inthe Bragg regime for slanted phase gratings. Results are compared with experimentally measuredquantities for singly exposed phase gratings in different polarization conditions and incident angleorientations. The limitations of using multiplexed holograms in multiplanar substrate interconnectionapplications are also discussed.