| Project/Area Number |
08555090
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
情報通信工学
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| Research Institution | Kanazawa University |
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Principal Investigator |
IIYAMA Koichi Kanazawa University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (90202837)
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| Co-Investigator(Kenkyū-buntansha) |
INOKUMA Takao Kanazawa University, Faculty of Engineering, Lectuere, 工学部, 講師 (50221784)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥10,700,000 (Direct Cost: ¥10,700,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥8,100,000 (Direct Cost: ¥8,100,000)
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| Keywords | Laser diode / Optical frequency sweep / Reflectometry / Optical interferometric sensor / Digital filter / Maximum entropy method / Noise |
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| Research Abstract |
The FMCW reflectometry using a laser diode as a light source was developed for diagnosing and characterizing optical waveguides and optical figers. The results of the study are as follows.
1. The spatial resolution is found to be degraded due to nolinearity of the optical frequency sweep, and the two methods were developed to enhance the spatial resolution ; one is modifying the modulation waveform of the injection cuurent of the laser by using a digital filter, and the other is modulating the injection current of the laser with a triangular signal on which a rectangular signal is superimposed. The spatial resolution was improved by a factor of 6, and the experimental resolution agreed with the theoretical resolution.
2. The maximum entropy method (MEM) was used to analyze the detected signal to achieve high spatial resolution. The spatial resolution by the MEM is smaller than the conventional theoretical resolution. The spatial resolution of about 100 mum was also achieved by using the extended MEM.
3. The incoherent FMCW reflectometry was developed to diagnose long optical fibers. The spatial resolution can be improved by using a light source with narrow linewidth. The spatial resolution of 60 m was achieved at the far end of an 11 km-long optical fiber. The Rayleigh backscattering in the fiber was also detected, and the propagation loss of the fiber and the connection loss of two fibers were estimated.
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