Browsing by Author "Lai, Chih Wei"

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Multiple-pulse microcavity lasing from an optically induced confinement
(2016-12-20)
Xie, Wei
;
Hsu, Feng-kuo
;
Lee, Yi-Shan
;
Lin, Sheng-Di
;
Lai, Chih Wei
Coupled electron-hole-photon systems in semiconductor microcavities have been a platform for studies of laser dynamics and nonequilibrium cooperative phenomena in solid states. Here, we report the observation of multiple-pulse lasing in optically induced confinement in a highly photoexcited semiconductor microcavity at room temperature. The spatially photomodulated refractive index changes enable an additional lateral photonic confinement, and discrete transverse modes result. Temporally and spectrally resolved measurements of the radiation reveal multiple sub-10-ps pulsed radiation commencing in order from high-to low-energy modes. Under a circularly polarized optical pumping, the high-energy mode emerges within 10 ps after the pulsed excitation and has a near-unity circular polarization. We attribute the observed cooperative effects to light-induced correlated e-h pairs in a high-density plasma and their effective coupling to discrete transverse modes in the spatially photomodulated optical confinement. (C) 2016 Optical Society of America
Transient dual-energy lasing in a semiconductor microcavity
(2015-10-19)
Hsu, Feng-Kuo
;
Xie, Wei
;
Lee, Yi-Shan
;
Lin, Sheng-Di
;
Lai, Chih Wei
We demonstrate sequential lasing at two well-separated energies in a highly photoexcited planar microcavity at room temperature. Two spatially overlapped lasing states with distinct polarization properties appear at energies more than 5 meV apart. Under a circularly polarized nonresonant 2 ps pulse excitation, a sub-10-ps transient circularly polarized high-energy (HE) state emerges within 10 ps after the pulse excitation. This HE state is followed by a pulsed state that lasts for 20-50 ps at a low energy (LE) state. The HE state is highly circularly polarized as a result of a spin-preserving stimulated process, while the LE state shows a significantly reduced circular polarization because of a diminishing spin imbalance.