Thermal index guiding in gain-guided blue-green II-VI semiconductor lasers

We have studied the lateral waveguiding properties of gain-guided and index-guided II-VI lasers under pulsed conditions and their influence on threshold current density J(th) and differential quantum efficiency eta. Thermal index guiding was found to reduce the astigmatism of the gain-guided devices. The thermally induced lateral field confinement leads to a lowering of J(th) and an increase of eta with pulse width with a maximum after a few mu s because of maximum overlap of the near field with the gain profile. For the index-guided devices the lateral waveguiding is fully determined by the built-in refractive index profile and no dependencies on pulse width are observed. (C) 1996 American Institute of Physics.