서지주요정보
모드록킹된 광섬유 레이저 자이로스코프의 이득 매질에 따른 출력 특성 및 향상된 신호처리 기법 연구 = Gain medium dependence of output characteristics and improved signal processing in mode-locked fiber laser gyroscope
서명 / 저자 모드록킹된 광섬유 레이저 자이로스코프의 이득 매질에 따른 출력 특성 및 향상된 신호처리 기법 연구 = Gain medium dependence of output characteristics and improved signal processing in mode-locked fiber laser gyroscope / 홍종범.
저자명 홍종범 ; Hong, Jong-Bum
발행사항 [대전 : 한국과학기술원, 2000].
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소장정보

등록번호

8010773

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 00016

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

Mode-locked fiber laser gyroscopes (ML-FLaG) with a semiconductor optical amplifier and an erbium-doped fiber (EDF) as a gain medium have been constructed, and the output characteristics of the ML-FLaG's have been investigated. Significant improvements in the performance of the ML-FLaG's have been made by applying a lock-in detection method for signal processing. The ML-FLaG is a fiber laser employing a Sagnac interferometer both as a rotation sensing element and a feedback reflector in a laser cavity. It consists of a laser cavity formed by a conventional mirror and a Sagnac interferometer, a gain medium, and a phase modulator inside the Sagnac loop interferometer. The output of a ML-FLaG is an optical pulse train having two pulses per every round-trip time of light in the laser cavity. The time interval between the two consecutive pulses varies as a function of rotation rate, that can be measured by using a time interval counter or a lock-in amplifier as described in this work. The ML-FLaG built with a semiconductor optical amplifier as a gain medium exhibited stable pulse train. However each output pulse was too wide and limited the dynamic range of the gyroscope, that originated from the rapid gain recovery time of the semiconductor optical amplifier compared to pulse intervals. To make optical pulses narrower, we have constructed a ML-FLaG with an EDF (ML-FLaG:EDF) as the gain medium, which shows a much slower gain recovery. The output pulse train exhibited significant instability due to gain competition, that could be suppressed by detuning the modulation frequency from the original longitudinal mode spacing of the laser However, the remaining fluctuation in the relative intensity of the two pulses, though very small, gave rise to non-negligible errors in the direct time interval measurement. Using a lock-in detection technique, the error terms could be easily removed by phase sensitive detection mechanism. Moreover, the direct output of the lock-in amplifier has a desirable linear dependence on the rotation rate, that is a great advantage over a sinusoidal dependence in conventional fiber-optic gyroscope. The dependence of the scale factor on the total output power can be removed by normalizing the output of the lock-in amplifier with respect to the average laser output power. The ML-FLaG:EDF using the lock-in detection showed the bias drift of about 0.8 deg/hr, corresponding to 10 μrad of phase error that was about 1/20 of that from the time interval measurement. The rms noise equivalent random walk was also improved to 0.018 deg/$\sqrt {hr}}$ which corresponded to 9 μrad/$\sqrt{Hz}}$. In summary, the work described in this thesis demonstrated ways to improve the performance of a ML-FLaG significantly by employing EDF as a gain medium, detuned modulation frequency, and a lock-in detection method.

서지기타정보

서지기타정보
청구기호 {DPH 00016
형태사항 ii, 99 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Jong-Bum Hong
지도교수의 한글표기 : 김병윤
지도교수의 영문표기 : Byoung-Yoon Kim
수록잡지명 : "Phase sensitive detection for mode-locked fiber laser gyroscope". Photonics technology letters, vol. 11, no. 8, pp. 1030-1032 (1999)
학위논문 학위논문(박사) - 한국과학기술원 : 물리학과,
서지주기 참고문헌 : p. 95-99
주제 자이로스코프
광섬유 레이저
신호 처리
모드록킹
이득 매질
Gyroscope
Fiber laser
Signal processing
Mode-loking
Gain medium
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