Influence of temperature on the angular distribution of radiation emitted by InGaAsP heterolasers

A reduction in the divergence of radiation emitted by InGaAsP heterolasers with increasing temperature was observed experimentally for the first time. A model of a waveguide with varying parameters was used in calculations which can explain the reduction in the width of the angular distribution and the increase in the threshold current with temperature. The results support the waveguide mechanism of the anomalous rise in the threshold current of long-wavelength InGaAsP heterolasers with temperature.