Browsing by Author "Hsu, Feng-kuo"

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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
Ultrafast spin-polarized lasing in a highly photoexcited semiconductor microcavity at room temperature
(2015-05-14)
Hsu, Feng-kuo
;
Xie, Wei
;
Lee, Yi-Shan
;
Lin, Sheng-Di
;
Lai, Chih-Wei
We demonstrate room-temperature spin-polarized ultrafast (similar to 10 ps) lasing in a highly optically excited GaAs microcavity. This microcavity is embedded with InGaAs multiple quantum wells in which the spin relaxation time is less than 10 ps. The laser radiation remains highly circularly polarized even when excited by nonresonant elliptically polarized light. The lasing energy is not locked to the bare cavity resonance, and shifts similar to 10 meV as a function of the photoexcited density. Such spin-polarized lasing is attributed to a spin-dependent stimulated process of correlated electron-hole pairs. These pairs are formed near the Fermi edge in a high-density electron-hole plasma coupled to the cavity light field.