Holographic edge-illuminated polymer Bragg gratings for dense wavelength division optical filters at 1550 nm

To meet the requirements of DWDM spectral filters at 1550nm, we suggest a new design for holographic Bragg gratings in photopolymers. The design is based on an edge-illuminated hologram configuration. Using this configuration, it is not difficult to make a very long grating and to apply apodization to the grating profile. A larger range of filter functions can be realized by cascading several gratings with different properties or by combining the gratings with other planar optical elements. Here, we show both simulated and experimental results using this arrangement. Rouard's method is used to examine the properties of apodized grating, and the results indicate the potential for narrow spectral bandwidths and high side lobe suppression. Experimental results with two types of photopolymer, Aprilis ULSH-500-7A and Phenanthrenequinone-doped PMMA, provide evidence of the effectiveness of this arrangement.