Scalable high-power (>1kW/cm^2) diode laser stacks based on silicon monolithic micro-channel coolers

Abstract

We describe the performance and reliability of high power vertical diode stacks based on silicon monolithic microchannel coolers (SiMMs) operating at >1000W/cm 2 CW at 808 and 940nm. The monolithic nature of these stacks makes them inherently robust and compact. Typical emitting dimensions for a 10-bar stack are ~8.8mm x 10mm with CW output power up to 1.5kW. Originally developed at Lawrence Livermore National Laboratory and now actively being developed for commercial applications at Coherent, this technology offers several advantages over current copper-based micro-channel coolers. These devices do not require use of DI water, strict monitoring and control of the pH level, careful control of the water velocity, or sealed cooling systems. The need for hydrostatic seals is also drastically reduced. A typical ten bar stack requires only 2 o-ring seals, compared to 20 such seals for a similar stack using copper microchannel cooling. Mature and readily available wet etching technology allows for cost effective batch fabrication of the sub-mount structure while achieving repeatable high precision components based on photolithographic fabrication processes.

Highly stable conductively cooled 1 kW - QCW diode laser stacks with high duty cycle

“…Microchannel failure is avoided by using different heat sink materials such as silicon [8] or by using "macro channels" instead of micro channels [6]. Unfortunately thermal resistance is degraded for these designs.…”