Photopolymer-based demultiplexers with Superposed holographic gratings

A photopolymer-based demultiplexer structure with two superposed holographic gratings is proposed and demonstrated for the first time. The demultiplexer is constructed from a holographic recording with two coherent beam sets. In the proposed scheme, two different channels of optical signals are coupled into a common single-mode fiber (SMF) by means of diffractions from the two superposed gratings. The coupled spectral channels are selected by tuning the spatial location of the SMF. The wavelength separation between two spectral channels that couple into the same optical fiber can be controlled by varying the angle between the two beams used for the formation of the holographic gratings.