Membrane guided-mode resonant color filters exhibiting adjustable spectral response

We demonstrate membrane guided-mode resonant color filters exhibiting adjustable spectral response using freestanding subwavelength HfO2 gratings. Color filters capable of reflecting arbitrary colors can be achieved by varying the grating periods. Three primary colors with efficiencies of 55.3%, 73.2% and 62.5% are observed for filters with periods of 320, 400, and 500 nm, respectively. Resonance wavelength tuning capability of 120 nm is attained through adjustment of incident angle of input light using a filter with period of 320 nm. Blue, green, and red color responses are observed at 0°, 13°, and 31°, respectively. These membrane devices provide an approach for color filtering and spectral imaging with extremely compact structure.