New Submount Requirement of Conductively Cooled Laser Diodes for Lidar Applications

초록

New sumount technology is essential for the development of conductively cooled high power diode laser. The simulation and experimental results indicate that thermal conductivity of submount for high power laser-diode must be at least 600W/m/K or higher for stable operation. We have simulated several theoretical thermal model based on new submount designs and characterized high power diode lasers to determine temperature effects on the performances of laser diodes. The characterization system measures the beam power, output beam profile, temperature distribution, and spectroscopic property of high power diode laser. The characterization system is composed of four main parts: an infrared imaging camera, a CCD camera, a monochromator, and a power meter. Thermal characteristics of two commercial-grade CW 20W diode laser bars with open heat-sink type were determined with respect to the line shift of emission spectra and beam power stability. The center wavelength of laser emission has a tendency to shift toward longer wavelength as the driving current and heat sink temeperature are increased. The increase of heat sink temperature decreases the output power of laser bar too. Such results lay the guideline for the design of new submount for high poweer laser-diodes.