Effects of the optical absorption of a LED chip on the LED package

The optical absorption rates of lateral and vertical chips are compared with the optical power before and after encapsulation to clarify the concomitant changes. The optical power of lateral chip after packaging with phosphor is higher than that of vertical chip. The difference increases with phosphor content. We argue that chip absorption rate is one of the most important factors in LED packaging because significant amount of light from a chip is reintroduced into the chip by backward scattering at phosphors and reflection at encapsulation surface.