Tunable color filter with non-subwavelength grating at oblique incidence

Abstract

An angle controlled guided-mode resonant (GMR) color filter with 1D grating is proposed for resonant wavelength at oblique incidence. A Ta2O5 grating based GMR filter was fabricated, which exhibits tunable filtering feature. The grating with a period of 574 nm was fabricated utilizing a two-beam interference system and ion beam etching. A resonant wavelength varying in the entire visible spectrum is demonstrated experimentally. For TM -polarization, as the incident angle increases from 20° to 50°, the resonant wavelength decreases from 670.32 nm to 463.21 nm, which covers the entire visible wavelength. The grating period is larger than the resonant wavelength when the incident angle is larger than 30.6°, i.e. the structure works under non-subwavelength conditions, which leads to a reduction of the difficulties associated with pattern production. The structure was calculated by rigorous coupled-wave analysis method. Our design may promote the application of the GMR color filter.