Browsing by Author "Xie, Wei"

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A Spin-controlled Microcavity Laser
(2015)
Hsu, Feng-Kuo
;
Xie, Wei
;
Lee, Yi-Shan
;
Lin, Sheng-Di
;
Lai, Chih-Wei
We demonstrate highly circularly polarized lasing under non-resonant elliptically polarized optical pumping in a semiconductor microcavity at room temperature. (C) 2014 Optical Society of America
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
Room-Temperature Macroscopic Coherence of Two Electron-Hole Plasmas in a Microcavity
(2020-04-16)
Jie, Qi
;
Zhang, Keye
;
Lai, Chih-Wei
;
Hsu, Feng-Kuo
;
Zhang, Weiping
Macroscopic coherence of Bose condensates is a fundamental and practical phenomenon in many-body systems, such as the long-range correlation of exciton-polariton condensates with a dipole density typically below the exciton Mott-transition limit. Here we extend the macroscopic coherence of electron-hole-photon interacting systems to a new region in the phase diagram-the high-density plasma region, where long-range correlation is generally assumed to be broken due to the rapid dephasing. Nonetheless, a cooperative state of electron-hole plasma does emerge through the sharing of the superfluorescence field in an optical microcavity. In addition to the in situ coherence of e-h plasma, a long- range correlation is formed between two 8-mu m-spaced plasma ensembles even at room temperature. Quantized and self-modulated correlation modes are generated for e-h ensembles in the plasma region. By controlling the distance between the two ensembles, multiple coupling regimes are revealed, from strong correlation to perturbative phase correlation and finally to an incoherent classical case, which has potential implications for tunable and high-temperature-compatible quantum devices.
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.
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.