Coherence properties of high-β elliptical semiconductor micropillar lasers

The authors report complementary investigations on the coherence properties of spontaneous and stimulated emission from (In,Ga)As∕GaAs quantum-dot-based high-quality semiconductor micropillar cavities. Low temperature microphotoluminescence measurements on an elliptically shaped micropillar revealed a clear polarization splitting (ΔE∼45μeV) of its fundamental mode. Full conformity is found with an oscillatory behavior observed in corresponding g(1)(τ) first-order field correlation measurements. In addition, power-dependent g(1)(τ) series on a single polarization component of the lasing mode have systematically revealed a strong coherence time increase from τc∼25to∼430ps, which traces the change of emission characteristics from thermal to coherent light.