The number of channels of an optical communication system is increasing rapidly. In this paper, the demonstration of a
130-channel demultiplexer based on the cascaded volume holographic gratings is presented. Those gratings are
recorded separately in 100-μm thickness photopolymer films, which attached on both sides of a glass substrate. They
have different grating periods, slant angles, and center wavelengths. By ultilizing this configuration, the operating
wavelength range of the optical demultiplexer could be expanded, and therefore, the number of channels of the
holographic demultiplexer is increased. As a result of the experiment, a 0.4-nm-spaced demultiplexer with the channel
uniformity of 3.5 dB, the 3dB-bandwidth of 0.12 nm, and the channel crosstalk of -20 dB is experimentally achieved.