Cross-link optimized cascaded volume hologram array with energy-equalized one-to-many surface-normal fan-outs

Achieving a uniform fan-out energy distribution is critical to the successful applications of substrate guided-wave optical interconnects. Using Dupont photopolymer film HRF-600X001-20, we investigated the optimum recording beam intensity for obtaining a large dynamic region of diffraction efficiency relative to exposure dosage. Based on the experimental diffraction efficiency curve, 1-to-5 and 1-to-9 surface-normal fan-out devices were fabricated that operated at a wavelength of 850 nm, and output nonuniformities of $\pm 4$% and $\pm 10$% were obtained for the two devices.