| Project/Area Number |
63550010
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied materials
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| Research Institution | University of Electro-Communications |
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Principal Investigator |
SAWADA Takayuki University of Electro-Communications, Electronics Engineering, Associate Prof., 電気通信学部, 助教授 (40113568)
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| Co-Investigator(Kenkyū-buntansha) |
UJIHARA Kikuo University of Electro-Communications, Prof., 電気信学部, 教授 (90017351)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1988: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | BSO / Photorefractive Crystal / Phase Conjugate Wave / Space Charge Layer / Deep Impurity Level / Thermally Stimulated Current / Image Processing / Diffraction Efficiency / 位相共役波 / 旋光性 / 光電流 / 2光波混合 |
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| Research Abstract |
Purposes of the present study are to characterize BSO crystals by means of simultaneous optical and electrical measurements, and to clarify the degree of correspondence between material parameters deduced from photorefractive properties and those from electrical properties. Main results obtained are following:
1. Optical Characterization: (1) Photorefractive properties such as steady-state intensity of the phase conjugate wave (PCW) and recording time versus light-induced grating spacing characteristics can be fundamentally explained by the "band transport model". (2) Effective acceptor density giving rise to photorefractive properties can be determined from the PCW intensity versus fringe spacing curve. (3) A rigorous method for determining the effect of optical activity on PCW intensity and its polarization angle was developed; a maximum diffraction efficiency can be obtained for the transverse configuration with a static electric field generated along the <001> direction. (4) The pro
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duct of the donor concentration and photoionization cross section was determined from the gain coefficient of the two-beam coupling with running hologram. (5) The dependence of the recording time on the acceptor concentration is quite different between the carrier drift region and the carrier diffusion region.
2. Electrical Characterization: (1) Material parameters such as carrier mobility, diffusion length and acceptor concentration, determined from steady-state and dynamic photocurrents, are found to be in reasonably agreement with those from photorefractive measurements. (2) Six impurity levels are detected from thermally stimulated current (TSC) measurements, and their influence on photorefractive properties become evident. (3) A new method to characterize the space charge layer formed underneath electrodes is proposed. (4) The above simple electrical measurements are useful for predicting the photorefractive properties.
3. Capability of Optical Information Recordings; The resolving angle and the crosstalk of multiple optical information recordings are studied, and minimum resolving angle without crosstalk is determined. Less
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