Coated submicron gratings for broadband antireflection in solar energy applications

Experiments demonstrating the broadband antireflection performance of MgF2-coated surface-relief gratings in polymer foil are discussed. The measured mean reflectance was as low as 0·6% for the wavelength range of 400 to 1500 nm. As a consequence, the transmission losses at the glass surface of a solar energy device can be reduced from about 7·5% to 3·1%, averaged over the day. The coated gratings are more stable against heat than bare surface gratings and the MgF2 coating also exhibits better adhesion to the structured surface than it does to the plane surface.