Single-quantum-well laser with 11.2 degree transverse beam divergence

The authors report the operation of a single-quantum-well laser vertically integrated with four passive waveguides to achieve a record low beam divergence of 11.2 degrees . While the beam divergence is reduced by a factor of four when compared with a single-quantum-well laser, the threshold current increases by a factor of three. Analysis shows that it is possible to reduce the threshold current further while maintaining the same low beam divergence.