Analysis of Substrates for Single Emitter Laser Diodes

Abstract

Electrically conductive substrates (i.e., metals) are often used in the mounting of semiconductor laser diodes. While metals offer a good electrical and thermal performance, they restrict the system integration due to lack of signal routing capability. Since the implementations utilizing laser diodes have become more common, the integration level has also become an important factor in these products. Mounting of lasers on insulative substrates is the key to large-scale integration. Organic boards form the de facto standard of insulative substrates; however, their use with lasers is impossible due to low thermal conductivity. Ceramics, however, offer nearly the same thermal performance as metals but as electrically insulative materials also provide the foundation for high integration levels. In this study the effects of three different ceramic substrates on the stresses within diode lasers was evaluated. Finite element method was used to calculate the mounting induced straining and the thermal performance of the substrate. The same procedure was employed to examine the optimum metallization thickness for the ceramic substrates. The results present how greatly the substrate material can affect the very delicate laser diode. The ceramic substrates, though having nearly the same properties, exhibited clearly distinctive behavior and a great difference in thermal and mechanical performance.