Analytical treatment of light extraction from textured surfaces using classical ray optics

Regular periodic textures e.g., microlens arrays, micro-pyramids, and cones on substrate surface have been used to enhance light out-coupling in light emitting devices. Photon randomization, often associated with surface roughening, has been suggested as the mechanism for out-coupling enhancement. This article analytically investigates the ray dynamics in a light emitting device when periodic texture is used as an external out-coupler. An attempt has been made to understand the relationship between enhancement in out-coupling and the surface inclination of these structures using classical ray optics.