GaSb-Based Optically Pumped Semiconductor Disk Laser Using Multiple Gain Elements

We report on the realization of an optically pumped semiconductor disk laser (SDL) emitting at 2.25-mu m wavelength with a cavity containing two separately pumped (AlGaIn)(AsSb) gain chips. Compared to single-chip SDLs, the dual-chip configuration allows launching a significantly larger amount of total pump power into the laser chips prior to reaching thermal rollover of the output power characteristics. At a chip submount temperature of 20degC, a maximum continuous-wave output power of 3.3 W was achieved in this way for an absorbed pump power of ap30 W. A detailed analysis of the lasing characteristics of the dual-chip SDL revealed increased round-trip losses due to the increased number of cavity elements. However, a reduction of the slope efficiency could be circumvented by increasing the output coupling mirror transmittance.