二郎天明 | Shizuoka University (original) (raw)

Papers by 二郎天明

電子情報通信学会技術研究報告; 信学技報, May 11, 2006

SIAM International Conference on Data Mining, May 17, 2007

IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Nov 25, 1978

IEEE Journal of Quantum Electronics, 1994

The degradation behavior of 0.98-μm strained quantum well (QW) InGaAs/AlGaAs lasers with facet co... more The degradation behavior of 0.98-μm strained quantum well (QW) InGaAs/AlGaAs lasers with facet coating films is systematically clarified at high-power operations of more than 100 mW/facet. The degradation is mainly caused by the instability of the interface between the laser material (facet) and the antireflecting (AR) coating film. This phenomenon is associated with a high rate of facet oxidation and

Solid-state Electronics, 1996

We found a new self-organizing growth mode in the metalorganic vapor-phase epitaxy (MOVPE) on hig... more We found a new self-organizing growth mode in the metalorganic vapor-phase epitaxy (MOVPE) on high-index GaAs (31l)B substrates to form well-ordered arrays of quantum-dots. The spontaneous interaction of strained InGaAs layers with AlGaAs buffer layers results in high-density rows of disk-shaped InGaAs quantum dots buried within AlGaAs microcrystals due to lateral mass transport. The size and distance of the disks are controlled independently in the mesoscopic size range by the In composition and the InGaAs layer thickness, respectively, without affecting the uniformity and the shape. The photoluminescence spectra exhibit narrow linewidth and high efficiency at room temperature. Buried quantum disk structures are formed also on other GaAs (n 1 I)B substrates and on InP (311)B substrates, indicating this growth mode to be universal in the strained layer growth on high-index semiconductor surfaces.

The success of digital and analog signal transmission experiments using Pr-doped fibre amplifier ... more The success of digital and analog signal transmission experiments using Pr-doped fibre amplifier (PDFA) modules has resulted in the need to develop a plug-in type PDFA module, which is assembled on a printed-board for practical field applications. In order to achieve this, it is essential to have highly efficient Pr3+-doped fiber and high-power laser diodes (LDs). We believe we have

IEEE Photonics Technology Letters, Apr 1, 1991

A long-wavelength monolithically integrated highsensitivity single-channel photoreceiver and a tw... more A long-wavelength monolithically integrated highsensitivity single-channel photoreceiver and a two-channel receiver array which requires only a single 5 V power supply are demonstrated. Both devices were fabricated using Be ion implantation and MOVPE grown crystals. The single-channel photoreceiver offers a world-class sensitivity of-33.6 dBm for 622 Mb/s together with wide dynamic range of 21.6 dB. A twochannel receiver array exhibited a sensitivity of-32 dBm and a dynamic range of 22 dB with a well-suppressed crosstalk level below-30 dB.

IEEE Photonics Technology Letters, Sep 1, 1992

Pr3+-doped fluoride fiber amplifier pumped by demonstrated. A net gain of 15.1 dB is achieved for... more Pr3+-doped fluoride fiber amplifier pumped by demonstrated. A net gain of 15.1 dB is achieved for a 1.31 p m signal at a pump power of 160 mW. was used. The refractive-index of the core glass was raised ference between the core and cladding of 3.7% (NA = 0.42) was adopted to improve the gain coefficient. The newly developed high-Power 1.017 P m laser diode modules is by the addition of PbF,. A relative refractive-index dif

Physical review, Jun 15, 1996

We investigate the optical transition of a small number of In 0.4 Ga 0.6 As quantum dots fabricat... more We investigate the optical transition of a small number of In 0.4 Ga 0.6 As quantum dots fabricated by selforganized growth on a ͑311͒B GaAs substrate by microscopic photoluminescence and excitation spectroscopy. The luminescence shows very sharp peaks. By tuning the detection at these peaks, discrete and narrow absorption lines are observed in the excitation spectrum, which are assigned to zero-dimensional ͑0D͒ quantized levels. Resonant excitation experiments clarify their discrete nature, which is a manifestation of zero dimensionality. This discreteness allows us to detect a single dot selectively, even when a number of dots are illuminated. Analysis of the homogeneous broadening of these 0D quantized levels indicates that there is no threshold behavior at LO-phonon energy. ͓S0163-1829͑96͒01023-5͔

A spectroscopic method, which enables characterization of a single isolated quantum dot and quant... more A spectroscopic method, which enables characterization of a single isolated quantum dot and quantum wave function interferometry is applied to exciton discrete excited state in InGaAs quantum dot. Long coherence of zero-dimensional excitonic states made possible the observe coherent population flopping in a 0D excitonic two-level system in a time-domain interferometric measurement and corresponding energy splitting is also manifested in an energy-domain measurement.

SIAM International Conference on Data Mining, May 8, 2003

The absorption spectra in an exciton-biexciton system were measured in InGaAs quantum dots by a s... more The absorption spectra in an exciton-biexciton system were measured in InGaAs quantum dots by a single dot spectroscopy. The spectra exhibit strong optical nonlinearity effects induced by coherent interactions between exciton and biexciton states. Quantum dots have been attracting much attention because of their distinctive exciton-biexciton physics and important contribution to quantum information processes. We report on the strong optical nonlinearity in exciton absorption found in zero-dimensional InGaAs quantum dots by using single-dot photoluminescence excitation (PLE) spectroscopy. We measured the absorption spectrum of an exciton interacting with a biexciton in isolated quantum dots. In a quantum dot with a weak confinement effect, the exciton absorption spectrum exhibits unusual lineshapes with transparent structures at the exciton resonant energy for a large biexciton population. A pump-probe-like technique ensures that the exciton state almost disappears as a result of the quantum interference effects in the exciton and the biexciton states. The InGaAs quantum dots were grown by MOVPE on a GaAs (311) B substrate. The photoluminescence (PL) and PLE for single quantum dots were measured with the micro-PL technique. The pump-probe-like measurement technique used a Mach-Zehnder interferometer to excite the quantum dots. Figure 1 shows the measured PL and PLE spectra for a single quantum dot. The PL spectrum contains clearly separated PL peaks from an exciton and a biexciton. The energy separation between the peaks is the biexciton binding energy. The binding energy is about 2.6 meV which means relatively large size quantum dots with weak confinement effects. This indicates that the dipole moments of the exciton and biexciton are much larger than those of the quantum wells and bulk. Figure 1 also shows PLE spectra for an exciton (X) and biexciton (XX), which correspond to absorption spectra. Several PLE peaks reveal the discrete density-of-states achieved in higher states. We focus on level A in the PLE spectra. Large signals can be seen in both X and XX spectra. When the laser energy is set at level A, an exciton and a biexciton are simultaneously created. The corresponding energy level structure is also shown. The energy structure is a coherently interacting three-level system. We evaluate the coherent effects in an exciton and a biexciton. Figure 2 shows PLE spectra of X and XX with a fine energy resolution for different excitation intensities. With a low excitation, peak-shaped spectra can be seen in X and XX. However, these spectral shapes change greatly with increasing excitation. With a high excitation, XX PLE spectrum is peak-shaped with a broadened linewidth. The X PLE has an unusual spectral shape with dip-shaped structure. As in Fig.2, the absorption almost disappears at the exciton resonance energy. A large coherent effects between X and XX yielded this unusual PLE. Coherent Rabi oscillation between X and XX causes energy splitting in the X level resulting in the dip-shaped X PLE spectrum. The large dipole

The study deals with fine adjustment of the responses of wide-bandwidth SAW filter by trimming in... more The study deals with fine adjustment of the responses of wide-bandwidth SAW filter by trimming interdigital transducer filter's fingers by hand. It is shown that by trimming finger lengths, amplitude responses can be adjusted to be the desired flat response near the center frequency.

HAL (Le Centre pour la Communication Scientifique Directe), Sep 11, 2012

映像情報メディア学会技術報告, Jan 27, 2003