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論文

論文
Kuwamura, Yuji ; Yamada, Minoru ; Ichino, Yukihiro ; Fukamura, Isao ; Sekikawa, Toshihisa ; 桑村, 有司 ; 山田, 実
出版情報: Japanese Journal of Applied Physics.  43  pp.7109-7110,  2004-10-01.  The Japan Society of Applied Physics (JSAP) 応用物理学会
URL: http://hdl.handle.net/2297/00058218
概要: 金沢大学工学部電子情報工学科/Department of Electrical and Computer Engineering, Faculty of Engineering, Kanazawa University<br />The a mplification of optical light excited by a traveling electron in a vacuum environment was first observed in the near-infrared optical region as that in a Cherenkov-type amplifier. Light with a wavelength of 1.5 µm propagated in a Si–SiO2 dielectric waveguide. The accelerated voltage of the electron beam for the amplification was approximately 42 kV. The dispersion relation between wavelength and acceleration voltage well agreed with theoretically calculated results.<br />Embargo Period 12 months 続きを見る
2.

論文

論文
Fares, Hesham ; Yamada, Minoru
出版情報: Physics of Plasmas.  18  pp.93106-,  2011-09-01.  American Institute of Physics (AIP)
URL: http://hdl.handle.net/2297/29455
概要: In this paper, the operation of the stimulated emission in Cerenkov free-electron laser (CFEL) is studied on the basis o f the modulations of electron velocity and density by the electromagnetic (EM) field. The influence of the electron relaxation, due to mutual electrons collisions, on the electron dynamics is taken into account. We investigate the growth characteristics of Cerenkov laser operating in the small-signal and saturation regimes. In the saturation regime, the effect of velocity reduction of the electron beam on the gain dynamics is demonstrated. We also show that our results match with those of other well-known treatments in the small-signal gain limit. © 2011 American Institute of Physics. 続きを見る
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論文

論文
Fares, Hesham ; Yamada, Minoru
出版情報: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.  659  pp.519-524,  2011-12-11.  Elsevier B.V.
URL: http://hdl.handle.net/2297/29753
概要: In this paper, a quantum mechanical model is proposed to describe the basic features of stimulated Cherenkov radiation i n the small-signal low-gain regime. In this model, the electron is described by a wavepacket with finite spreading length and the electron wave function is a solution of the Schrödinger equation. We show that the quantum effects are manifested when the spreading length of the electron wave is much longer than the electromagnetic (EM) wavelength such as in the optical wavelength range. The effect of electron relaxation due to Coulombs collisions with neighboring electrons is introduced to characterize the damping of the vibration of the electron wave with time. When the relaxation effect is neglected, we prove that our essential results match with other classical and quantum approaches based on different theoretical concepts. © 2011 Elsevier B.V. All rights reserved. 続きを見る
4.

論文

論文
Imran, Sazzad M.S. ; Yamada, Minoru ; Kuwamura, Yuji
出版情報: IEEE Journal of Quantum Electronics.  48  pp.521-527,  2012-01-01.  IEEE
URL: http://hdl.handle.net/2297/30329
概要: An improved theoretical model to analyze the dynamics and operation of semiconductor lasers under optical feedback has b een presented in this paper. A set of rate equations are formulated, in which the self and mutual gain saturation effects among lasing modes, reinjection of delayed feedback light reflected at the surface of the connecting optical device, and Langevin noise sources for the intensity and phase fluctuations are taken into account. The proposed model is applied to 850-nm GaAs lasers operating under optical feedback. The rate equations are calculated by tracing time variation, and frequency spectra of intensity noise are determined with the help of the fast Fourier transform. In this paper, numerical simulations based on our theoretical model confirmed that the feedback noise is classified into two types based on profiles of the frequency spectrum, where one is the low-frequency type and another is the flat type. These properties are in good agreement with those previously obtained in the experimental measurements. This evidence of agreement between experimental results and numerical simulations supports the accuracy of our model. © 2006 IEEE. 続きを見る
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論文

論文
Yamada, Minoru
出版情報: IEEE Journal of Quantum Electronics.  48  pp.980-990,  2012-01-01.  IEEE
URL: http://hdl.handle.net/2297/31972
概要: A theoretical analysis of the intensity and the frequency noise in semiconductor optical amplifiers (SOA) is given. Ampl ification of a traveling optical wave is formulated associating with fluctuations on the optical intensity, the optical phase, and the electron numbers based on the classical wave-equation and quantum mechanical modification. Inclusion of the amplified spontaneous emission generated in the SOA is also taken into account. Amounts of noise are expressed in terms of the relative intensity noise (RIN), the spectrum line-width, and the frequency noise. Sensitive dependency of the RIN property on the optical input power is theoretically explained. The RIN increases after passing the SOA, when the optical input power is small enough, but decreases when the optical input power is rather high. On the while, the spectrum line-width is found to be scarcely changed from the input light for conventional operation of the SOA. © 2012 IEEE. 続きを見る
6.

論文

論文
Imran, Sazzad M.S. ; Yamada, Minoru
出版情報: IEEE Journal of Quantum Electronics.  49  pp.196-204,  2013-01-01.  IEEE = Institute of Electrical and Electronics Engineers
URL: http://hdl.handle.net/2297/34122
概要: Semiconductor lasers tend to suffer from the optical feedback (OFB) noise caused by the reflection of the output light a t the surface of the optical disc or the optical fiber. Superposition of high frequency (HF) current is used as a technique to suppress the OFB noise. However, this is not effective when the frequency of the HF current coincides with a rational number of the round trip time for the OFB. This paper shows numerical simulations on the phenomena of the OFB noise, its suppression by the superposition of HF current and conditions at which the HF current is unable to suppress the noise. The model used here is based on multimode rate equations that include nonlinear gain, Langevin noise sources, the OFB, and the HF superposition. Generating mechanism of the OFB noise and its suppression are explained with approximated but analytical equations. Excellent correspondence between experimental data and simulation is also demonstrated. © 1965-2012 IEEE. 続きを見る
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論文

論文
Yamada, Minoru ; Fares, Hesham
出版情報: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.  709  pp.108-119,  2013-01-01.  Elsevier B.V.
URL: http://hdl.handle.net/2297/34123
概要: A generalized theoretical analysis for amplification mechanism in the planar-type Cherenkov laser is given. An electron is represented to be a material wave having temporal and spatial varying phases with finite spreading length. Interaction between the electrons and the electromagnetic (EM) wave is analyzed by counting the quantum statistical properties. The interaction mechanism is classified into the Velocity and Density Modulation (VDM) model and the Energy Level Transition (ELT) model basing on the relation between the wavelength of the EM wave and the electron spreading length. The VDM model is applicable when the wavelength of the EM wave is longer than the electron spreading length as in the microwave region. The dynamic equation of the electron, which is popularly used in the classical Newtonian mechanics, has been derived from the quantum mechanical Schrödinger equation. The amplification of the EM wave can be explained basing on the bunching effect of the electron density in the electron beam. The amplification gain and whose dispersion relation with respect to the electron velocity is given in this paper. On the other hand, the ELT model is applicable for the case that the wavelength of the EM wave is shorter than the electron spreading length as in the optical region. The dynamics of the electron is explained to be caused by the electron transition between different energy levels. The amplification gain and whose dispersion relation with respect to the electron acceleration voltage was derived on the basis of the quantum mechanical density matrix. © 2013 Elsevier B.V. 続きを見る
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論文

論文
Yamada, Minoru ; Tera, Itaru ; Matsuoka, Kenjiro ; Hama, Takuya ; Kuwamura, Yuji
出版情報: IEICE Transactions on Electronics.  pp.1444-1446,  2012-08-01.  IEICE
URL: http://hdl.handle.net/2297/32458
概要: Reduction of the intensity noise in semiconductor lasers is an important subject for the higher performance of an applic ation. Simultaneous usage of the superposition of high frequency current and the electric negative feedback loop was proposed to suppress the noise for the higher power operation of semiconductor lasers. Effective noise reduction of more than 25 dB with 80mW operation was experimentally demonstrated. Copyright © 2012 The Institute of Electronics, Information and Communication Engineers. 続きを見る
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論文

論文
Yamada, Minoru ; Hesham, Fares
出版情報: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.  709  pp.108-119,  2013-01-01. 
URL: http://hdl.handle.net/2297/34654
概要: A generalized theoretical analysis for amplification mechanism in the planar-type Cherenkov laser is given. An electron is represented to be a material wave having temporal and spatial varying phases with finite spreading length. Interaction between the electrons and the electromagnetic (EM) wave is analyzed by counting the quantum statistical properties. The interaction mechanism is classified into the Velocity and Density Modulation (VDM) model and the Energy Level Transition (ELT) model basing on the relation between the wavelength of the EM wave and the electron spreading length. The VDM model is applicable when the wavelength of the EM wave is longer than the electron spreading length as in the microwave region. The dynamic equation of the electron, which is popularly used in the classical Newtonian mechanics, has been derived from the quantum mechanical Schrödinger equation. The amplification of the EM wave can be explained basing on the bunching effect of the electron density in the electron beam. The amplification gain and whose dispersion relation with respect to the electron velocity is given in this paper. On the other hand, the ELT model is applicable for the case that the wavelength of the EM wave is shorter than the electron spreading length as in the optical region. The dynamics of the electron is explained to be caused by the electron transition between different energy levels. The amplification gain and whose dispersion relation with respect to the electron acceleration voltage was derived on the basis of the quantum mechanical density matrix. © 2013 Elsevier B.V. 続きを見る
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論文

論文
Makinoshima-Higuchi, Kazuki ; Takeuchi, Nobuhito ; Yamada, Minoru
出版情報: IEICE Transactions on Electronics.  E97C  pp.1093-1103,  2014-11-01.  IEICE = 電子情報通信学会
URL: http://hdl.handle.net/2297/40177
概要: Amplification characteristics of the signal and the noise in the semiconductor optical amplifier (SOA), without facet mirrors for the intensity modulated light, are theoretically analyzed and experimentally confirmed. We have found that the amplification factor of the temporarily varying intensity component is smaller than that of the continuous wave (CW) component, but increases up to that of the CW component in the high frequency region in the SOA. These properties are very peculiar in the SOA, which is not shown in conventional electronic devices and semiconductor lasers. Therefore, the relative intensity noise (RIN), which is defined as ratio of the square value of the intensity fluctuation to that of the CW power can be improved by the amplification by the SOA. On the other hand, the signal to the noise ratio (S/N ratio) defined for ratio of the square value of the modulated signal power to that of the intensity fluctuation have both cases of the degradation and the improvement by the amplification depending on combination of the modulation and the noise frequencies. Experimental confirmations of these peculiar characteristics are also demonstrated. 続きを見る