Temperature-dependent polarization behavior of semiconductor lasers

InGaAsP lasers are found to operate in a pure TM mode or in a mixture of TE and TM modes at low temperatures. The polarization change at low temperatures is attributed to a thermal-stress effect in the InGaAsP active layer. However, none of the AlGaAs/GaAs lasers tested exhibits such behavior because the thermal stress in the active layer is significantly offset by the GaAs substrate.