Thermal management strategies for high power semiconductor pump lasers

Semiconductor pump lasers are an important component in erbium-doped fiber amplifiers and Raman amplifiers. Thermal management has become one of the major obstacles of pump laser development. Understanding of the thermal behavior of high-power laser packages is crucial to the thermal design and optimization of pump lasers. In this paper, we report on the thermal characteristics of a high-power pump laser and discuss the issues associated with heat dissipation. The thermal management of high-power pump laser modules mainly consists of three aspects. One is the thermal resistance reduction which reduces bulk temperature rise in the laser diode chip. The second is facet temperature control, and the third is the thermoelectric cooler (TEC) coefficient of performance improvement. In this paper, the approaches to reduce thermal resistance and facet temperature at the chip level and package level will be reviewed, and the thermal design and optimization of the package assembly to improve the TEC coefficient of performance will be discussed. The thermal resistance of a pump laser could be reduced up to 40% by the proper design of the laser chip and epi-down bonding. An unpumped window design in the pump laser diode is proven to be very effective in reducing the facet temperature and increasing the catastrophic optical mirror damage level. Assembly and package optimization can provide more uniform temperature distribution on TEC cold plate which is critical in improving the TEC coefficient of performance.