Dual-polarization, single quantum-well AlGaInP laser diode structure

A single quantum-well Ga/sub 0.5+/spl delta//In/sub 0.5-/spl delta//P/(AlGa)/sub 0.5/In/sub 0.5/P laser structure is demonstrated, which can provide similar gain in both polarizations. The slightly tensile-strained quantum-well has a light-hole ground state, which gives the lowest transparency current for TM-mode gain. However, the TE-mode gain is dominant at high drive currents. The gain-current relationships have been characterized for each polarization, and found to cross at a modal gain value of 25 cm/sup -1/. Lasers whose threshold gain is near this crossover value were found to emit in either one or both polarizations, with a very wide range of polarization asymmetry possible. A simple QW gain model can be used to qualitatively describe this behavior, along with the tendency toward TE-mode emission at higher temperature.<
>