| Co-Investigator(Kenkyū-buntansha) |
UEDA Masahito Faculty of Engineering, Associate Professor, 工学部, 助教授 (70271070)
ISHIHARA Teruya Faculty of Engineering, Associate Professor, 工学部, 助教授 (60168250)
SHIMIZU Akira University of Tokyo, Graduate School of Arts and Science, Professor, 総合文化研究所, 助教授 (10242033)
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| Research Abstract |
1) Semiconductor Light Emitters based on the quantum control of electron and photon systems
a) Spontaneous emission control by microcavity : Using quantum confined Stark effect (QCSE), it was shown that, under optical excitation, various characteristics of the spontaneous emissions such as the emission intenisity, radiation patterns, and the rediative recombination lifetime are modified in semiconductor microcavities. Then, as a prototype of the practical device, semiconductor microcavity light emitters, which has both the functions of carrier injection by current and the application of electric field in the QW, was fabricated and, at low temperature, the device operation has been confirmed. In addition to these experiments on spontaneous emission control, the influence of the oscillator strength and the linewidth of the excitons on the cavity-polariton dispersion, which apears in high-Q micorcavities, has been clarified experimentally. Also, the possibility of THz electromagnetic wave
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generation was pointed out (patented).
b) Sub-poissonian photon flux generation : The mechanisms of the sub-Poissionian light generation in semiconductor light emitting diodes (LEDs) were investigated experimentaly and theoreticaly. The role of the electron or hole pump and the recombination processes was clarified. In the experiments, even by the use of commercially available LEDs, it was shown that the generation of sub-Poissionian lights over a wide frequency range, 100 MHz is possible under constant-current operation. In addition, the sub-Poissonian lights was shown to be generated even under constant-voltage operation, by the use ot series-connected LEDs. These experiments were performed at room temperature. In theoretical studies, QCSE blockade for the photon generation was proposed. By computer simulations, it was shown that even under constant voltage operation, the photon number fluctuations are squeezed in 10-photon scale, under ultra-low current level (〜10nA), in very short time-scale (100ps).
2) Theories on the interactions between low-dimensional electrons and quantized photon field It was pointed out that there arises various problems in the former theoretical framework of the cavity quantum electrodynamics (QED) in a medium. By taking into account the polarizations in a medium as quantized freedums, various QED effects such as the photon generation by dynamical Casimir effect and the spontaneous emissions in absorptive cavity were investigated.
3) Spontaneous emission control in natural quantum wells Distributed feedback reflector micorcavity formed by the corting of thin natural quantum well films ((C6H5C2H4NH3)2PbI4) on a grating-patterned substrate was proposed. The formation of polariton modes and the directional spontaneous emissions were ovserved. Less
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