Ikuo Suemune

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We experimentally demonstrate Cooper pairs' drastic enhancement of the band-to-band radiative recombination rate in a semiconductor. Electron Cooper pairs injected from a superconducting electrode into an active layer by the proximity effect recombine with holes injected from a p-type electrode. The recombination of a Cooper pair with p-type carriers(More)
This Letter theoretically discusses the photon emission spectra of a superconducting p-n junction. On the basis of the second order perturbation theory for electron-photon interaction, we show that the recombination of a Cooper pair with two p-type carriers causes enhancement of the luminescence intensity. The calculated results of photon emission spectra(More)
We experimentally prepare bi-photon mixed states in polarization employing an entangled-classical hybrid photon emitter which can properly model solid-state entangled photon sources with uncorrelated background photons. Polarization-uncorrelated photon pairs in totally mixed (TM) states are embodied with classical thermal radiation, while the(More)
We introduce a novel three-step procedure for precise niobium (Nb)-etching on the nanometer-scale, including the design of high contrast resist patterning and sacrifice layer formation under high radio frequency (RF) power. We present the results of precise slit fabrication using this technique and discuss its application for the production of(More)
Vicinal 4H and 6H-SiC(0001) surfaces have been investigated using atomic force microscopy and cross-sectional high-resolution transmission electron microscopy. We observed the characteristic self-ordering of nanofacets on any surface, regardless of polytypes and vicinal angles, after gas etching at high temperature. Two facet planes are typically revealed:(More)
Modified spontaneous emission properties in the presence of confined photon modes inside the three-dimensional (3-D.) optical microcavities are demonstrated. Self-formed pyramidal-shaped semiconductor structures fabricated by selective-area growth technique are utilized as an optical microcavity in which discrete photon modes are generated. Noticeable(More)
We numerically and theoretically investigate electrodynamics of a metal-embedded semiconductor microdisk cavity. The electrodynamics of a cavity mode is discussed from the viewpoint of quantum mechanics, which clarifies the condition for high Q factor. Using numerical calculations, we optimize the cavity structure and show that the Q factor can be increased(More)
Enhancement of optical absorption in thin-film solar cells (TF-SCs) has been the long-lasting issue to achieve high efficiencies. Grating couplers have been studied for the conversion of incident light into guided modes propagating along TF-SCs to extend optical path for higher optical absorption. However the wavelength band for the efficient conversion(More)
We study the spectral diffusion in a single epitaxial InAs quantum dot placed in a silver-embedded nanocone structure. Making use of a series of stroboscopic detection of optical transitions, we demonstrate the temporal fluctuations in peak energy of photoluminescence. In particular, the photoluminescence fluctuations can be effectively suppressed by strong(More)