Improving the color uniformity of multiple colored light-emitting diodes using a periodic microstructure surface.

This study looks at the performance of a periodic microstructure surface on multiple colored light-emitting diodes (LEDs). A periodic microstructure surface on the package was used to reshape the light from the different colored LED chips in the multiple colored LEDs, which decreased the color separation and color nonuniformity of the multiple colored LEDs. Experimental results show that the multiple colored LEDs with a periodic microstructure surface could achieve medium or high collimation as well as good color uniformity. Thus, this study provides a simple and cost-effective method to greatly improve the color uniformity of multiple colored LEDs with medium or high collimation.

Analysis of position-dependent light extraction of GaN-based LEDs.

The light extraction efficiency of GaN-based LEDs as a function of the position of the light source over the active layer is studied. Several parameters, including chip dimensions, absorption coefficients and package are analyzed on the basis of a Monte-Carlo ray tracing simulation. The light extraction efficiency of a Thin-GaN LED is studied with respect to a sapphire-based LED, including the surface texture.