Efficient Guided-Mode-Resonant Tunable Color Filters

A new angle-tuned guided-mode resonance color filter is experimentally demonstrated. The device is designed using numerical methods and patterned using laser interferometric lithography. It consists of a 55-nm-deep silicon nitride and air diffraction grating with a 270-nm grating period along with a 110-nm-thick silicon nitride waveguide layer deposited on a glass substrate. The fabricated filter exhibits blue, green, and red color responses at incident angles of 8
$^{\circ}$
, 20
$^{\circ}$
, and 35
$^{\circ}$
, respectively. It has a bandwidth of 10 nm with efficiency near 90%.