Controlled self-assembly of peptides on graphite via rational mutation
This paper has been withdrawn by the author due to a missing figure
q-bio.BM↗
arXiv subjects
Yuhei Hayamizu
Publications and source records attributed to Yuhei Hayamizu.
Room-temperature excitonic absorption in quantum wires
We measured absorption spectra of T-shaped quantum wires at room temperature using waveguide-transmission spectroscopy. Strong and narrow room-temperature one-dimensional-exciton absorption peak was observed, which shows peak modal absorption coefficient of 160 cm$^{-1}$ per 20 wires with $Γ$-factor of $4.3\times10^{-3}$, width of 7.2 meV, and strong polarization anisotropy.
cond-mat.mes-hall↗
Evolution of excitons via biexcitons to an electron-hole plasma without level crossing between band edge and exciton in a quantum wire
A recent single quantum wire is of sufficient quality to reveal new details of the photoluminescence (PL) evolution with increasing electron--hole (e--h) pair density. At a pair density of 3.6 $\times$ 10$^{3}$ cm$^{-1}$, the PL is characteristic of biexcitons shifted below the exciton peak by the 2.8-meV biexciton binding. At the pair density of 1.2 $\times$ 10$^{5}$ cm$^{-1}$, the biexciton peak broadens without energy shift to an e--h plasma. At all pair densities up to 30 K, neither the exciton peak nor the one-dimensional (1D) continuum edge shows any shift. In contrast to prevailing theories, the low-energy edge of the plasma PL line never crosses the exciton peak and never makes contact with the 1D e--h continuum.
cond-mat.mes-hall↗
Strong photo-absorption by a single quantum wire in waveguide-transmission spectroscopy
We measured the absorption spectrum of a single T-shaped, 14x6 nm lateral-sized quantum wire embedded in an optical waveguide using waveguide-transmission spectroscopy at 5 K. In spite of its small volume, the one-dimensional-exciton ground state shows a large absorption coefficient of 80 /cm, or a 98 % absorption probability for a single pass of the 500-um-long waveguide.
cond-mat.other↗
Polarization-dependent photoluminescence-excitation spectra of one-dimensional exciton and continuum states in T-shaped quantum wires
We measured polarization-dependent photoluminescence-excitation spectra of highly uniform T-shaped quantum wires at 5 K. We attribute one peak to the 1D-exciton ground state and the continuous absorption band to 1D continuum states. These had similar polarization-dependences. We also observed some other peaks above the 1D-exciton ground state and attribute them to exciton states consisting of excited hole subbands. These results show good agreement with a model calculation of a single electron-hole pair in T-shaped geometry with exact diagonalizations of the Coulomb interaction.
cond-mat.mtrl-sci↗
Imaging of emission patterns in a T-shaped quantum wire laser
Spatially and spectrally resolved microscopic images of spontaneous and stimulated emissions are imaged at the mirror facets of a GaAs T-shaped quantum wire laser with high uniformity. Laser emission from the one-dimensional ground state reveals a circular image located at the core of a T-shaped optical waveguide but significantly smaller in area than the low power spontaneous emission from the same waveguide. These images unambiguously allow assignment of all spontaneous and laser emissions to the wire ground state and respective intersecting wells in the structure.
cond-mat.mtrl-sci↗
Lasing from a single quantum wire
A laser with an active volume consisting of only a single quantum wire in the 1-dimensional (1-D) ground state is demonstrated. The single wire is formed quantum-mechanically at the T-intersection of a 14 nm Al_{0.07}Ga_{0.93}As quantum well and a 6 nm GaAs quantum well, and is embedded in a 1-D single-mode optical waveguide. We observe single-mode lasing from the quantum wire ground state by optical pumping. The laser operates from 5 to 60 K, and has a low threshold pumping power of 5 mW at 5 K.
cond-mat.mtrl-sci↗