Packaging of high power density double quantum well semiconductor laser array using double-side cooling technology

Abstract

High power diode laser arrays offer a variety of applications in pumping of solid state laser systems for industry, scientific research, entertainment display and medical treatment etc, due to their higher electrical-optical conversion efficiency, compact size and long lifetime. Currently, most of commercial high power semiconductor laser array^ar products use single quantum well (SQW) construction in the active region. In order to achieve higher optical power at lower driving current without altering the radiation characteristics of the laser diodes, a new laser chip constructed by double quantum well (DQW) active region has been developed. For the DQW laser, two layers of individual emitters are stacked on top of each other. The two layers of emitters in a DQW are in serial connection. Hence, compared with the conventional SQW laser, a doubled output power from DQW under the same drive current could be obtained. However, the transient/peak thermal density generated from these lasers is very high, especially for the up layer in the active region of DQW laser. Therefore, the DQW can more suitably operate in quasi-continuous wave (QCW) mode. It is a challenge to dissipate the heat generated from the up layer of DQW laser. In this work, a double-side cooling technology was developed and the packaging of high power density DQW semiconductor laser array using that technology was presented. Finite element numerical analysis based simulations to analyze the transient thermal behavior of a water-cooled-packaged semiconductor laser array operating at QCW mode was also presented in this paper. Based on the numerical simulation and analysis, a series of DQW semiconductor lasers with high performances were fabricated. The performances of laser diode arrays operating at QCW mode, including the characteristics of Power-Current-Voltage (LIV), spectrum, near-field, and lifetime were characterized.