Enhancement of light extraction from resonant cavity light-emitting diodes using a 2-D grating embossed in TiO₂ Sol-Gel

To enhance the light extraction efficiency of a resonant cavity light-emitting diode (RCLED), a soft embossing technique was developed to fabricate a 2-D grating on the RCLED output surface. The optimal 2-D grating parameter was designed by a rigorous coupled wave analysis code. By embossing the 2-D grating on the output of a commercial RCLED, a 49% light extraction enhancement was achieved using a novel high refractive index (N = 2) TiO₂ sol-gel and a 24% enhancement using a UV curable polymer with lower refractive index (n = 1.56). The overall emission pattern was also modified making the patterned RCLED potentially easier to couple into a fiber.