Holographic filter with cascaded volume Bragg gratings in photopolymer waveguide film

A novel holographic filter using a photopolymer-based cascaded volume Bragg gratings (CVBGs) is proposed and experimentally demonstrated in this paper. The filter was designed to attain a narrow spectral bandwidth characteristic without increasing the thickness of photopolymer used, at 1550 nm operating wavelength region. The proposed filter is consisted of a 45° slanted grating working as a surface-normal input/output coupler and a non-slanted reflection grating acting as a narrow-band wavelength selective filter, and it was embedded in the photopolymer film as a waveguide mode. The fabricated filter showed that the bandwidth at the center wavelength of 1547.85 nm was about 0.45 nm.