99% Diffraction Efficiency Leaky Mode Sustained Resonant Gratings and Susceptibility to Laser Damage

A resonant diffraction grating comprising a mirror, a dielectric layer and a corrugation at the layer-air interface is shown to exhibit a record diffraction efficiency of more than 99% in the – 1
^st
reflected order at 1064 nm wavelength. The leaky mode field enhancement in the high index grating raises the issue of laser damage.