Optical pumping injection cavity (OPIC) for high-efficiency mid-IR "W" lasers

Abstract

We report a new optical pumping injection cavity (OPIC) approach that combines a high pump absorbance with long pump wavelength and a thin active layer. High absorbance is achieved by tuning an etalon cavity to the pump wavelength, which brings about multiple passes of the pump beam through the active region. A 12- 1/2 period distributed Bragg reflector (DBR) consisting of alternating AlAs/sub 0.08/Sb/sub 0.92/ and GaSb layers was grown onto the GaSb substrate. The 2/spl lambda//sub pump/ central cavity consisted of a 0.51 /spl mu/m thick GaSb spacer, a 100 /spl Aring/ AlAs/sub 0.08/Sb/sub 0.92/ hole-blocking layer, a l0-period InAs/GaSb/InAs/AlAsSb (17 /spl Aring//35 /spl Aring//17 /spl Aring//44 /spl Aring/) W active region, another hole-blocking layer, and another spacer. The OPIC pump cavity was completed by a 7-period top GaSb/AlAsSb DBR. Although the OPIC is resonant in the vertical direction at /spl lambda//sub pump/, at the mid-IR wavelength, the mirror stacks function as cladding layers and the spacers function as high-index separate confinement regions. Thus the laser operates in an edge-emitting configuration. Pumping was by 107 ns pulses from a 2.098 /spl mu/m Ho:YAG laser, operating at a repetition rate of 1 Hz.