Measurement of junction temperature of a semiconductor laser diode

Normally, laser diodes (LDs) are mounted on heat sinks to dissipate the heat energy to avoid overheating. But even when a laser-diode is mounted on a heat sink; the active layer temperature or junction temperature can rise significantly above the heat sink temperature because of thermal resistance of various layers of a laser diode. Junction temperature affects laser diode performance in many ways. Therefore, the thermal design of a laser diode itself and the packaging in which it is encased becomes crucial to the overall performance of the device. In this paper, a simple technique for the estimation of junction temperature of a semiconductor laser diode is developed. This technique is successfully applied for the measurement of junction temperature of a semiconductor LD.