Full-color reflectance-tunable filter based on liquid crystal cladded guided-mode resonant grating

This work proposes a tunable reflective guided-mode resonant (GMR) filter that incorporates a 90 degrees twisted nematic liquid crystal (TNLC). The GMR grating acts as an optical resonator that reflects strongly at the resonance wavelength and as an alignment layer for LC. The 90 degrees TNLC functions as an achromic polarization rotator that alters the polarization of incident light. The resonance wavelength and reflectance of such a filter can be controlled by setting the angle of incidence and driving the 90 degrees TNLC, respectively. The designed filter exhibits a very large spectral shift in resonance wavelength from 710 to 430 nm, which covers the entire visible spectrum. The transmittance can be tuned to within 10 V at various resonance wavelengths. The hybrid GMR - LC filter is compact, has a simple design, and is easy to fabricated. It can therefore be used in practical applications. (C)2016 Optical Society of America