| Project/Area Number |
59460033
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理学一般
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| Research Institution | Kyoto University |
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Principal Investigator |
YABUZAKI Tsutomu (1986) Radio Atmospheric Science Center, Kyoto University, Associate Professor, 国立大学(その他), 助教授 (60026127)
薮崎 努 京都大学, 助教授
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| Co-Investigator(Kenkyū-buntansha) |
KITANO Masao Radio Atmospheric Science Center, Kyoto University, Research Associate, 超高層電波研究センター, 助手 (70115830)
OGAWA Toru Radio Atmospheric Soience Center, Kyoto University, Professor, 超高層電波研究センター, 教授 (60025822)
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| Project Period (FY) |
1984 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥7,600,000 (Direct Cost: ¥7,600,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1985: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1984: ¥3,900,000 (Direct Cost: ¥3,900,000)
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| Keywords | Optical Bistability / 非線型現象 |
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| Research Abstract |
This project was on a new type of optically bistable system which exhibits symmetry-breaking bifurcations. We proposed this system and studied theoretically and experimentally on its static and dynamical behavior. The bistability is based on the optically induced Faraday effect due to the spin polarization in alkali atoms. It can be achieved by a single feedback of the light beam without the use of an optical cavity unlike other systems. The states of the system can be characterized by the orientation of atomic spin polarization or by the helicity of the light in the cell. The symmetry-breaking bifurcation was clearly demonstrated experimentally.
We also predicted that continuous spin precession can be possible when we apply a transverse magnetic field to the system. The spin precession is sustained by the optical feedback despite the thermal relaxation. Recently, the precession was confirmed experimentally. The precession frequency was proportional to the magnetic field amplitude as ex
… More
pected by the theory. The upper limit of the frequency (-10MHz) turned out to be limited by the presence of magnetic inhomogeneity. Without this, more rapid oscillation can be possible.
We also studied on chaotic behavior which can be seen in this system. With use of numerical calcurations, we found many interesting strange attractors and bifurcations. Among them "symmetry recovering crises" and "hidden chaos", which we named, was found to be universal phenomena seen in various physical systems.
As an extension of our system, we analysed a two-beam system, where the two parts are coupled through the atomic diffusion. In the no-coupling case, it is easy to see that the system shows quadrastability. We found that, even in other cases, it can possess four stable states, if we use laser beams intense enough. We can further extend the analysis to N-beam and two-dimensional systems, which will play an impatient role in optical computers in future.
We note that stimulated by our proposal to utilize spin polarization for optical bistability, several groups in the world have been worked out and obtained many fruitful results. Less
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