Tunable Filter With Varied-Line-Spacing Grating Fabricated Using Holographic Recording

In this letter, we experimentally demonstrate a compact and tunable guided-mode resonance (GMR) filter incorporates a varied-line-spacing (VLS) grating layer that is fabricated using holographic interference lithography. The reflectance wavelength varies as a function of the spatial position on the structure. In an interference exposure system, a cylindrical lens is placed between the collimating mirror and the sample to achieve a VLS grating at different positions on the photo-resist film. The grating period increment is approximately 108 nm over a length of 22 mm, which results in a primary reflectance peak that spans 762.1-908.3 nm. The device is designed using the rigorous coupled-wave analysis method, and the proposed device is directed toward the practical application of GMR tunable filters.