Expansion of channel number in optical demultiplexer using cascaded photopolymer volume gratings

A method to expand the number of channels in the optical demultiplexer (DMUX) using two cascaded photopolymer volume gratings is proposed and presented. A 0.4-nm-spaced 130-channel DMUX with the channel uniformity of 3.5 dB, the 3-dB bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally demonstrated.