論文 - 菅野 敦史
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W-band photonic signal generation with carrier and unnecessary sidebands suppressed by second harmonic generation 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS 348 - 349 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
We demonstrate 100GHz (W-band) photonic signal generation at 775 nm by optical modulation and spectral shaping at 1.55 μm combined with second harmonic (SH) generation with a periodically poled lithium niobate waveguide. ©2008 IEEE.
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W-band live electro-optic imaging system 査読あり
Atsushi Kanno, Kiyotaka Sasagawa, Masahiro Tsuchiya
2008 EUROPEAN MICROWAVE CONFERENCE, VOLS 1-3 552 - + 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IEEE
A real-time electro-optic imaging technique for W-band electric-field distribution has been successfully realized for the first time. On the basis of high-bandwidth photonics, the system provides instantaneous 100x100-pixels visualization of the W-band intensity and phase distribution along with phasor images. For a demonstration of the measurement performance, 100-GHz wave emission patterns from a WR-10 waveguide flange were visualized.
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V-band Signal Generation by Photonic Frequency Doubling with Periodically Poled Lithium Niobate Waveguide 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
2008 INTERNATIONAL TOPICAL MEETINGS ON MICROWAVE PHOTONICS AND 2008 ASIA-PACIFIC MICROWAVE PHOTONICS CONFERENCE 127 - 130 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IEEE
In this paper, we propose and demonstrate a novel photonic signal generation method for V-band applications, where a two-tone photonic signal is provided with a combination of optical modulation and optical frequency doubling. Based on the method, a fundamental light at 1.55 mu m is modulated at a frequency of 30 GHz and the optical frequency is doubled with a periodically poled lithium niobate (PPLN) waveguide. The experimental result is in agreement with the calculation and a V-band two-tone signal at 775 nm with a frequency separation of 60 GHz is obtained.
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Ultrafast optical Kerr effect of excitons weakly confined in GaAs thin films
Atsushi Kanno, Redouane Katouf, Osamu Kojima, Junko Ishi-Hayase, Masahiro Tsuchiya, Toshiro Isu
Physica Status Solidi (C) Current Topics in Solid State Physics 5 ( 1 ) 360 - 363 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
We investigate ultrafast response of optical Kerr effect (OKE) induced by excitons weakly confined in GaAs thin films. The observed decay time of optical response agrees approximately with incident pulse duration. At 100-fs pulse irradiation the response time is estimated to be 170 fs, though the exciton lifetime is about 10 ns. It is considered that the ultrafast response of OKE is caused by not population relaxation but orientation relaxation of excitons. © 2008 WILEY-VCH Verlag GmbH &
Co. KGaA. -
Spectral width dependence of residual carrier effect on nonlinear optical response of weakly confined excitons
O. Kojima, T. Isu, J. Ishi-Hayase, M. Sasaki, A. Kanno, R. Katouf, M. Tsuchiya
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 9 5 ( 9 ) 2858 - 2860 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：WILEY-V C H VERLAG GMBH
We report residual carrier effects on the nonlinear optical response of weakly confined excitons in GaAs thin films. The nonlinear response was investigated using a degenerate four-wave mixing technique with an additional pulse to create the residual carriers. In the case of the additional-pulse incidence, the signal intensity decreases with the time of incidence. However, the ultrafast component comparable to the pulse width in the temporal profiles does not change appreciably. Our results imply the possibility of the realization of ultrafast switching using the exciton response. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Phase-resolved visualization of 100 GHz traveling electromagnetic waves by an EO imaging method 査読あり
Atsushi Kanno, Kiyotaka Sasagawa, Masahiro Tsuchiya
Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS 218 - 219 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
The first phase-resolved visualization of traveling electromagnetic waves using the live electrooptic imaging method is reported. Stroboscopic images of wave electric-field intensity and phase are achieved instantaneously. ©2008 IEEE.
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Multi-channel measurement of RF complex refractive index by live electrooptic imaging camera 査読あり
Atsushi Kanno, Kiyotaka Sasagawa, Masahiro Tsuchiya
2008 INTERNATIONAL TOPICAL MEETINGS ON MICROWAVE PHOTONICS AND 2008 ASIA-PACIFIC MICROWAVE PHOTONICS CONFERENCE 259 - 262 2008年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IEEE
The concept of multi-channel RF complex refractive index measurement using a live electrooptic imaging (LEI) camera is proposed. The complex refractive index of water has been successfully evaluated with the transmitted microwave intensity and phase information being acquired within 0.5 s in a parallel manner suggesting that the instantaneous observation functionality of the LEI camera could be beneficial for prompt diagnosis and analysis of time-varying samples. The obtained refractive indices coincide well with those reported in the literature.
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Live electrooptic imaging system based on ultraparallel photonic heterodyne for microwave near-fields
Kiyotaka Sasagawa, Atsushi Kanno, Tetsuya Kawanishi, Masahiro Tsuchiya
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 55 ( 12 ) 2782 - 2791 2007年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
We report on 100 x 100 pixel live electrooptic imaging (LEI), which is real-time imaging of electrical signals on a microwave circuit. The circuit's electric near-fields can be depicted in real time on a display screen at video frame rates as high as 30 frames/s. This system is based on photonics technology in which electric near-fields are applied to an electrooptic crystal plate and a sensing light beam is modulated there. The frequency of modulation is down-converted by using a photonic heterodyne of large-scale parallelism, and the spatial pattern of the electroopitic modulation is detected with a high-speed image sensor. A digital signal processor is used to extract the frequency component of interest and to animate it on the display screen. As examples, we present live pictures of electric field pattern data acquired by the LEI system in a real-time manner.
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Instantaneous microwave transmission imaging of aqueous samples 査読あり
Atsushi Kanno, Kiyotaka Sasagawa, Masahiro Tsuchiya
2007 INTERNATIONAL TOPICAL MEETING ON MICROWAVE PHOTONICS 96 - 99 2007年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IEEE
We report on instantaneous microwave transmission imaging experiments using a photonic technique. A high-resolution electro-optic (EO) camera we developed was used as a microwave image sensor under near-field conditions. Microwave transmission images of water capsules could be depicted with 10,000 pixels in less than one second. The images using a combination of the observed microwave intensity and phase showed higher contrast. The spatial resolution was as fine as one tenth of the microwave wavelength. Our system is potentially applicable to microwave transmission imaging of aqueous objects and their diagnoses.
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Live electro-optic imaging of microwave near-fields via ultra-parallel photonic heterodyne 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Tetsuya Kawanishi, Masahiro Tsuchiya
2007 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, VOLS 1-6 401 - 404 2007年
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：IEEE
We present the first demonstration of fine Live Electro optic Imaging (LEI) of electrical signals on a microwave circuit. Patterns of their electric-near-fields are lively depicted on a display screen with a rate as high as 20 frames per second. In this system, a sensing light beam is modulated by an electro-optic (EO) crystal plate with the electric near-fields applied, and its spatial pattern of EO modulation are detected by a two-dimensional photo-detector array, where the frequency of modulation is down-converted by photonic heterodyne of large-scale parallelism. A digital signal processor (DSP) is employed to extract the frequency component of interest and to make it animated on the display screen. As examples, we present motion pictures of electric field pattern data acquired by the system in a real-time manner.
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Highly sensitive time-resolved Kerr rotation measurements on single-layer quantum dots
A Kanno, Y Masumoto
JOURNAL OF LUMINESCENCE 119 178 - 182 2006年07月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：ELSEVIER SCIENCE BV
We construct the highly sensitive Kerr rotation system to observe electron spin precession in single-layer quantum dots. The system consists of a photoelastic, modulator, a balanced detector and tandem double lock-in amplifiers. The angle resolution achieves 5 x 10(-6) degree, and is highest among the reported so far. To evaluate the possibility of measuring spin relaxation in single-layer quantum dots, we studied the strain-induced GaAs quantum dots. We observe successfully the electron spin precession in the single-layer quantum dots under resonant excitation. (c) 2006 Elsevier B.V. All rights reserved.
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Spin relaxation mechanism of strain-induced GaAs quantum dots studied by time-resolved Kerr rotation
Atsushi Kanno, Yasuaki Masumoto
Phys. Rev. B 73 ( 7 ) 073309 - 73309 2006年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：American Physical Society
We observed electron spin precession under magnetic field in single-layer quantum dots (QDs) by highly sensitive time-resolved Kerr rotation measurement. The spin lifetime is longer than that for the quantum well (QW). This is a result of the additional spatial confinement of electrons in QDs. Below 60 K, the spin lifetime is almost constant, and is 7 times shorter than the carrier lifetime. This suggests that the strong electron-hole exchange interaction dominates over the electron spin lifetime in QDs at low temperature.
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Confined acoustic vibration modes in CuBr quantum dots
M Ikezawa, JL Zhao, A Kanno, Y Masumoto
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 74 ( 11 ) 3082 - 3087 2005年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：PHYSICAL SOC JAPAN
Confined acoustic phonons in CuBr quantum dots (QDs) are studied for the first time using coherent phonon measurements and persistent spectral hole burning (PSHB) spectroscopy. A size-dependent damped oscillation with sub-THz frequency is observed in femtosecond pump-probe measurements of CuBr QDs in glass. Similarly, a size-dependent acoustic phonon hole with an energy shift of 1-2 meV is observed in PSHB spectra of CuBr QDs in glass and NaBr crystals. The energies of the confined acoustic phonons obtained by the two methods are in good agreement with each other. In addition, there is no difference in size-dependence between the glass matrix and NaBr matrix. The size dependence of acoustic phonons can be explained well as low frequency vibrational modes of CuBr QDs based on an elastic sphere model. The dominant mode is assigned to the l = 2 spheroidal mode, while the l = 0 mode is also observed.
DOI： 10.1143/JPSJ.74.3082
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Longitudinal optical phonons in the excited state of CuBr quantum dots
J Zhao, A Kanno, M Ikezawa, Y Masumoto
PHYSICAL REVIEW B 68 ( 11 ) 113305-1-4 2003年09月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：AMER PHYSICAL SOC
The size dependence of the longitudinal optical (LO) phonons in the excited state of CuBr quantum dots (QD's) in glass and NaBr crystals in the intermediate confinement regime was studied by means of persistent spectral hole burning spectroscopy. The phonon-exciton coupled states were clearly observed at a photon energy of about 2.993 eV when the LO phonon energy is close to the energy difference between the ground 1S and excited 1P states of CuBr QD's in glass. The energies of the LO phonons observed in smaller CuBr QD's in glass and NaBr crystals were determined to be about 18.6 and 17.6 meV, respectively, which are smaller than that of LO phonons in the bulk CuBr material. The energy softening of the LO phonons was explained in terms of the phonon renormalization.
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Photoinduced electric dipole in CuCl quantum dots
Y Masumoto, F Naruse, A Kanno
JOURNAL OF LUMINESCENCE 102 629 - 634 2003年05月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：ELSEVIER SCIENCE BV
Electromodulated absorption spectra of CuCl quantum dots modulated at twice the modulation frequency of electric field, 2f, show prominent structure around persistently burned hole. It grows in proportion to square of the electric field in the same manner as the 2f component of electromodulated absorption spectra of the dots without the laser exposure. Even the 2f component of electromodulated signal was observed around the burned hole position. These observations are explained by considering electric dipole formed in hole burned and photoionized quantum dots. Photoionization not only produces persistent spectral hole burning but also the local built-in electric field and photoinduced dipole moment in quantum dots. The dipole moment is estimated to be about 5 debye for 3.2-nm-radius quantum dots. The dipole moments are randomly oriented but 1% anisotropy is deduced from the electromodulated signal at (C) 2003 Elsevier Science B.V. All rights reserved.
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Longitudinal optical phonons in the excited state of CuBr quantum dots 査読あり
Jialong Zhao, Atsushi Kanno, Michio Ikezawa, Yasuaki Masumoto
Physical Review B - Condensed Matter and Materials Physics 68 ( 11 ) 2003年
記述言語：英語 掲載種別：研究論文（学術雑誌）
The size dependence of the longitudinal optical (LO) phonons in the excited state of CuBr quantum dots (QD’s) in glass and NaBr crystals in the intermediate confinement regime was studied by means of persistent spectral hole burning spectroscopy. The phonon-exciton coupled states were clearly observed at a photon energy of about 2.993 eV when the LO phonon energy is close to the energy difference between the ground 1S and excited 1P states of CuBr QD’s in glass. The energies of the LO phonons observed in smaller CuBr QD’s in glass and NaBr crystals were determined to be about 18.6 and 17.6 meV, respectively, which are smaller than that of LO phonons in the bulk CuBr material. The energy softening of the LO phonons was explained in terms of the phonon renormalization. © 2003 The American Physical Society.
