GaSb-based 2.3 /spl mu/m quantum-well diode-lasers with low beam divergence

A new design for the vertical waveguide structure of (AIGaIn)(AsSb)-based diode lasers is presented. The active layers of all investigated samples consist of compressively strained 10 nm wide Ga/sub 0.64/In/sub 0.36/As/sub 0.10/Sb/sub 0.90/-QWs, separated by 20 nm wide lattice matched Al/sub 0.29/Ga/sub 0.71/As/sub 0.02/Sb/sub 0.98/ barriers. The emission wavelength is 2.3 /spl mu/m at room temperature. This new quantum-well diode laser design exhibits reduced beam divergence in the fast axis, while the laser performance is maintained compared to a standard large divergence waveguide design. This strong decrease in the fast axis divergence drastically increases the fiber coupling efficiency of GaSb-based diode lasers.