1989 Fiscal Year Final Research Report Summary
Two-Dimensional Optical Bistability
| Project/Area Number |
62460065
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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 |
物理計測・光学
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| Research Institution | Kyoto University |
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Principal Investigator |
YABUZAKI Tsutomu Department of Physics, Kyoto University, Associate Professor, 理学部, 助教授 (60026127)
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| Co-Investigator(Kenkyū-buntansha) |
KITANO Masao Department of Electronics, Kyoto University, Lecturer, 工学部, 講師 (70115830)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Optical Bistability / Spin Polarization / Symmetry Breaking |
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| Research Abstract |
We Proposed and studied on a new type optical bistability, which is largely different from the ordinary one behaving with hysteresis. The optical system is very simple, which consists of a cell containing atoms with spin in the ground state, a lambda/8 plate and a mirror. This system has a positive feedback loop with respect to the spin polarizatim, so even if the incident light is linearly polarized with no angular momentum, atoms begin to have spin polarization when the incident light intensity exceeds a exceeds a critical value. In the present work, we have studied experimentally and theoretically on the behavior of specially coupled bistable systems, the coupling being through(1) light it self and (2) diffusion of spin-soarized atoms. At first we studied about the coupling of two systems, and found that the coupled system behaves with pitchfork bifurcation (symmetry breaking) at two different values of incident light intensity and it has four stable states in the strong intensity region. Next, the behavior of the system with continuously distributed bistable system has been studied. A laser beam with a large cross section is applied to the cell, and observed the spontaneously produced spin-polarization at each position of the cell, by detecting the special tribution of the Faraday rotation. We have found the existence of magnetic domain, in which all of spins are oriented to the same direction. It is also found that the steady state distribution of spin-polarization has spatial modes particularly in case of (1). All of experiments have been carried out with sodium vapor. Computer simulation with a simplified model was found to explain well the experimental results mentioned above.
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