| Project/Area Number |
09650052
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Okayama University |
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Principal Investigator |
WADA Osami Okayama University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10210973)
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| Co-Investigator(Kenkyū-buntansha) |
KOGA Ryuji Okayama University, Faculty of Engineering, Professor, 工学部, 教授 (20027147)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | optical resonator / wavelength division multiplexing / pillbox resonator / optical waveguide / optical modulator / optical filter / wavelength selectivity |
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| Research Abstract |
This research is to investigate the wavelength selective optical filter utilizing a pillbox optical resonator (Japan Patent No. 2713358, Oct. 311997) which the investigators of this project proposed. New application of the resonator has also been proposed in this research This optical filter is composed of a circular disk resonator and waveguides for input and out- put ; which are fabricated on electro-optical dielectric substrate.
In the first year, investigation on waveguide fabrication for the optical filter was performed. Analytical investigation on optimal design of the filter and on resonant wavelength control with electrodes were also performed. The results of analysis at 1.55 mum band show that a pillbox resonator with graded-index distribution has similar characteristics to a resonator with step-index which had been previously analyzed. Results of calculation about wavalength control are ; 104 GHz of FSR, 2.4 GHz of pass band width, 11V of applied voltage at as high as 800 MHz with larger extinction ratio than 20dB, with cross- talk less than-20 dB with channel separation 10 GHz The results show that the optical filter can be used as a high-speed wavelength-selective optical modulator (WSOM).
In the second year, the investigators found specific characteristics of WSOM ; peak output power of the modulator ex- ceeds 3 times as large as the CW input power at a specific modulation frequency with sinusoidal modulation signal close to the resonance. The investigators call this phenomenon as "amplifying modulation". By optimizing the modulation signal waveform, the factor of 6.5 of the modulation gain was achieved.
As for waveguide fabrication, a laser beam direct writing system was investigated. Characteristics related to the scanning speed of position controllers were tested and the control software was optimized. As a result it is concluded that required precision of fabrication was achieved to realize the proposed filter and the modulator.
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