論文 - 菅野 敦史
-
High-speed DBPSK signal generation by low-Vπ modulator using thin LiNbO3 substrate 査読あり
A. Kanno, T. Sakamoto, A. Chiba, T. Kawanishi, K. Higuma, M. Sudou, J. Ichikawa
Proc. ECOC2009 2009 ( 1 ) P2.09, pp.1-2 2009年
-
Real-time Visualization of W-band Millimeter Wave by Live Electro-optic Imaging 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
PIERS 2009 BEIJING: PROGESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM, PROCEEDINGS I AND II 48 - 51 2009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：ELECTROMAGNETICS ACAD
In this paper, W-band millimeter wave imaging is demonstrated by a live electric imaging (LEI) system, which has been recently developed. The LEI enables a real-time imaging of RF electric fields with 100 x 100 pixels and the frame rate of 30 frames/sec. LEI is based on ultra-parallel photonic heterodyning. To visualize millimeter wave electric field, a W-band photonic signal at a wavelength of 775 nm as a local oscillator is generated by frequency doubling of modulated light at 1550 nm. As an example, W-band LEI observation results for electric near-fields over the end of a waveguide are presented.
-
Optical Kerr response to multi pump pulses on GaAs weakly confined exciton
Atsushi Kanno, Redouane Katouf, Osamu Kojima, Junko Ishi-Hayase, Masahiro Tsuchiya, Toshiro Isu
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 6, NO 6 6 ( 6 ) 1509 - 1512 2009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 investigate optical Kerr response under two-pump pulse irradiation induced by GaAs weakly confined exciton. Ultrafast response times of the order of picoseconds are observed despite long exciton lifetime of the order of nanoseconds. The difference may be attributed to the relaxation mechanisms between population relaxation and nonlinear relaxation of excitons. In addition, the observed temporal shapes of the optical Kerr response are conserved under irradiation by a preceding pulse that forms the exciton population. The pulse separation of the optical Kerr response between two pump pulses is achieved to be 800 fs, which corresponds to a signal train of 1.25 Tbits per second. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
-
Real-time Visualization of W-band Millimeter Wave by Live Electro-optic Imaging 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
PIERS 2009 BEIJING: PROGESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM, PROCEEDINGS I AND II 48 - 51 2009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：ELECTROMAGNETICS ACAD
In this paper, W-band millimeter wave imaging is demonstrated by a live electric imaging (LEI) system, which has been recently developed. The LEI enables a real-time imaging of RF electric fields with 100 x 100 pixels and the frame rate of 30 frames/sec. LEI is based on ultra-parallel photonic heterodyning. To visualize millimeter wave electric field, a W-band photonic signal at a wavelength of 775 nm as a local oscillator is generated by frequency doubling of modulated light at 1550 nm. As an example, W-band LEI observation results for electric near-fields over the end of a waveguide are presented.
-
Phase-Evolving Real-Time Visualization of 100 GHz Traveling Waves 査読あり
Masahiro Tsuchiya, Atsushi Kanno, Kiyotaka Sasagawa, Takahiro Shiozawa
2009 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, VOLS 1-3 1673 - + 2009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 novel experimental scheme has been demonstrated for wave analyses in W-band. A system for phase-evolving real-time visualization of W-band waves has been constructed for the first time and has been applied to 100 GHz traveling wave analyses. Analyses on wave images/movies have been performed in conjunction with a numerical simulation approach. Described as an example of the wave analyses is a study on wave interactions between a semiconductor slab waveguide mode and a free space mode.
-
Ultrahigh Relative Refractive Index Contrast GaAs Nanowire Waveguides
Redouane Katouf, Naokatsu Yamamoto, Atsushi Kanno, Norihiko Sekine, Kouichi Akahane, Hideyuki Sotobayashi, Toshiro Isu, Masahiro Tsuchiya
APPLIED PHYSICS EXPRESS 1 ( 12 ) 122101-1-4 2008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：JAPAN SOCIETY APPLIED PHYSICS
An effective and practical fabrication procedure toward compound semiconductor nanowire waveguide on insulator is developed. GaAs nanowire waveguides with a cross-section of 400 x 400 nm(2), bend radius of 10 mu m, and a high relative refractive index contrast, Delta, of 40% were successfully fabricated for the first time. The propagation loss at 1.55 mu m was measured to be approximately 4.5dB/mm, and the bend loss was less than 0.8dB per 90 degrees bend. The losses were considered to be dominated by light scattering at the rough sidewalls. (C) 2008 The Japan Society of Applied Physics
-
Ultrahigh Relative Refractive Index Contrast GaAs Nanowire Waveguides
Redouane Katouf, Naokatsu Yamamoto, Atsushi Kanno, Norihiko Sekine, Kouichi Akahane, Hideyuki Sotobayashi, Toshiro Isu, Masahiro Tsuchiya
APPLIED PHYSICS EXPRESS 1 ( 12 ) 122101-1-4 2008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：JAPAN SOCIETY APPLIED PHYSICS
An effective and practical fabrication procedure toward compound semiconductor nanowire waveguide on insulator is developed. GaAs nanowire waveguides with a cross-section of 400 x 400 nm(2), bend radius of 10 mu m, and a high relative refractive index contrast, Delta, of 40% were successfully fabricated for the first time. The propagation loss at 1.55 mu m was measured to be approximately 4.5dB/mm, and the bend loss was less than 0.8dB per 90 degrees bend. The losses were considered to be dominated by light scattering at the rough sidewalls. (C) 2008 The Japan Society of Applied Physics
-
Instantaneous Visualization of K-Band Electric Near-Fields by a Live Electrooptic Imaging System Based on Double Sideband Suppressed Carrier Modulation
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
JOURNAL OF LIGHTWAVE TECHNOLOGY 26 ( 13-16 ) 2782 - 2788 2008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：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
This paper discusses instantaneous electric near-field imaging in the K-band. The imaging technique is based on the live electrooptic imaging (LEI) scheme, which was originally developed for electric near-field imaging in the microwave range. The measurement frequency of the LEI system is extended by using the second-order harmonic component of modulated light as a photonic local oscillator signal. We demonstrated electric near-field imaging over rather ordinary components such as an SMA connector and a microstrip transmission line at frequencies up to 25 GHz.
-
Decay of orientational grating of weakly confined excitons in GaAs thin films
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M. Sasaki, M. Tsuchiya
JOURNAL OF LUMINESCENCE 128 ( 5-6 ) 963 - 965 2008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
We report the dynamical properties of the exciton orientation in GaAs thin films using the orientational grating (OG) technique. From the results of excitation-power dependence of OG signal, we confirmed that the OG signal comes from the optical nonlinearity of weakly confined excitons. In addition, the OG-decay time decreases with an increase of excitation power due to exciton-exciton interaction, and the shortest decay time is below 1ps. Our results may imply the potential application of optical nonlinearity of weakly confined exciton to ultrafast switching devices operating at 1 Tbit/s. (C) 2007 Elsevier B.V. All rights reserved.
-
Effects of excitation spectral width on decay profile of weakly confined excitons
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M. Sasaki, M. Tsuchiya
JOURNAL OF LUMINESCENCE 128 ( 5-6 ) 966 - 968 2008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
We report the effect due to a simultaneous excitation of several exciton states on the radiative decay profiles on the basis of the nonlocal response of weakly confined excitons in GaAs thin films. In the case of excitation of single exciton state, the transient grating signal has two decay components. The fast decay component comes from nonlocal response, and the long-lived component is attributed to free exciton decay. With an increase of excitation spectral width, the nonlocal component becomes small in comparison with the long-lived component, and disappears under irradiation of a femtosecond-pulse laser with broader spectral width. The transient grating spectra clearly indicates the contribution of the weakly confined excitons to the signal, and the exciton line width hardly changes by excitation spectral width. From these results, we concluded that the change of decay profile is attributed not to the many-body effect but to the effect of simultaneous excitation of several exciton states. (C) 2007 Elsevier B.V. All rights reserved.
-
Photoluminescence dynamics of weakly confined excitons in GaAs thin films
Atsushi Kanno, Redouane Katouf, Osamu Kojima, Junko Ishi-Hayase, Masahide Sasaki, Masahiro Tsuchiya, Toshiro Isu
JOURNAL OF LUMINESCENCE 128 ( 5-6 ) 1069 - 1071 2008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
We investigate the dynamics of weakly confined excitons in GaAs thin films measured by time-resolved photoluminescence (PL) technique. When excitation energy was above the resonant energy of the exciton, a long PL rise time of about 200 ps was observed. It is considered that an exciton formation process from excited continuum energy states to discrete energy states of the exciton in the thin film causes the slow PL rise. The observed PL decay time constant was about 14 ns due to high quality fabricated samples. The observed population dynamics can be surely ascribed to the specific features of weakly confined excitons. (C) 2007 Elsevier B.V. All rights reserved.
-
Ultrafast response induced by interference effects between weakly confined exciton states
Osamu Kojima, Toshiro Isu, Junko Ishi-Hayase, Atsushi Kanno, Redouane Katouf, Masahide Sasaki, Masahiro Tsuchiya
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 77 ( 4 ) "044701 - 1"-"044701-4" 2008年04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
We report an ultrafast response of weakly confined excitons in GaAs thin films observed by a degenerate four-wave-mixing (DFWM) technique. The time-domain signals excited by broadband pulses show an oscillatory structure with a period that varies according to the pulse spectral width and an ultrafast response comparable to the pulse width; on the other hand, the exciton dephasing time is hardly changed by the excitation spectral width. This ultrafast response is much faster than the radiative lifetime expected on the basis of the nonlocal response theory. The DFWM spectra measured at various time delays clearly indicate the contribution of weakly confined excitons to the ultrafast response. Moreover, in the measurement of excitation-energy dependence, the time-domain signals excited by a controlled spectral width exhibit the variation of the oscillation period and response time. These characteristics are similar to those of the excitation spectral width dependence. From the analysis of oscillatory structures, it is found that the oscillation originates from the interference between weakly confined exciton states. Therefore, we conclude that the overlap of the oscillation due to the interference with the DFWM signal leads to the ultrafast response without any change in the exciton dephasing time. These results imply that the control of the excitation spectral width induces the ultrafast nonlinear optical response of the weakly confined excitons.
-
Ultrafast response induced by interference effects between weakly confined exciton states
Osamu Kojima, Toshiro Isu, Junko Ishi-Hayase, Atsushi Kanno, Redouane Katouf, Masahide Sasaki, Masahiro Tsuchiya
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 77 ( 4 ) "044701 - 1"-"044701-4" 2008年04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
We report an ultrafast response of weakly confined excitons in GaAs thin films observed by a degenerate four-wave-mixing (DFWM) technique. The time-domain signals excited by broadband pulses show an oscillatory structure with a period that varies according to the pulse spectral width and an ultrafast response comparable to the pulse width; on the other hand, the exciton dephasing time is hardly changed by the excitation spectral width. This ultrafast response is much faster than the radiative lifetime expected on the basis of the nonlocal response theory. The DFWM spectra measured at various time delays clearly indicate the contribution of weakly confined excitons to the ultrafast response. Moreover, in the measurement of excitation-energy dependence, the time-domain signals excited by a controlled spectral width exhibit the variation of the oscillation period and response time. These characteristics are similar to those of the excitation spectral width dependence. From the analysis of oscillatory structures, it is found that the oscillation originates from the interference between weakly confined exciton states. Therefore, we conclude that the overlap of the oscillation due to the interference with the DFWM signal leads to the ultrafast response without any change in the exciton dephasing time. These results imply that the control of the excitation spectral width induces the ultrafast nonlinear optical response of the weakly confined excitons.
-
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.
-
15 dB cross loss modulation by cw pump injection of mW-class in 1.5-mm long nano-wire waveguide 査読あり
R. Katouf, A. Kanno, N. Yamamoto, N. Sekine, T. K. Liang, K. Sasagawa, K. Akahane, T. Isu, H. Sotobayashi, M. Tsuchiya
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9 1184 - 1185 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
GaAs nano-wire waveguides were successfully fabricated on a SiO(2)/Si substrate for the first time. 15 dB; cross loss modulation was achieved by a few mW continuous-wave pump power within a 1.5 mm-long waveguide. (C)2008 Optical Society of America
-
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.
-
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. -
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.
-
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.
-
Live electro-optic imaging (LEI) for real-time analyses of electric near-fields over microwave circuits 査読あり
Kiyotaka Sasagawa, Atsushi Kanno, Masahiro Tsuchiya
PIERS 2008 HANGZHOU: PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM, VOLS I AND II, PROCEEDINGS 414 - 417 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：ELECTROMAGNETICS ACAD
Live electro-optic imaging (LEI) system is described in this paper, which enables the real-time imaging functionality of electrical signals on up to 10 GHz-class circuits in realtime on a screen at video frame rates as high as 30 frames per second. In the system, photonics provides important features of the system: its 100 x 100-channel parallel detection and the low invasiveness of electrooptic crystal. With the LEI system, novel diagnostic methods are provided through instantaneous and intuitive analyses of RF signal. distribution changes. As an example, LEI observation results for a coplanar waveguide with a moving metal plate axe presented.
