서지주요정보
테이퍼된 광섬유 구조에서의 모드결합에 관한 연구 = Mode coupling in tapered fiber structure
서명 / 저자 테이퍼된 광섬유 구조에서의 모드결합에 관한 연구 = Mode coupling in tapered fiber structure / 송광용.
저자명 송광용 ; Song, Kwang-Yong
발행사항 [대전 : 한국과학기술원, 2003].
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등록번호

8014245

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 03011

SMS전송

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초록정보

This dissertation describes the mode coupling in tapered fiber structure. The modal characteristics of tapered higher-order-mode fiber (HMF) are analyzed considering cladding-air boundary. As its application, we demonstrate novel fused-type mode selective couplers (FMSCs) that operate unique function in two-mode fiber (TMF) devices. Mode selective couplers (MSCs) are passive fiber-optic components that couple the $LP_{01}$ mode of a single-mode fiber (SMF) and the $LP_{11}$ mode of a TMF. They have been fabricated in the form of a polished coupler with a pair of a SMF and a TMF, where the phase-matching condition is satisfied between the $LP_{01}$ mode of the SMF and the $LP_{11}$ mode of the TMF. When compared to the polished-type MSCs, FMSCs have advantages of temperature-stability, compactness, and simple fabrication process. They don’t need special fiber pair to satisfy the phase-matching condition because SMF arm is simply prepared by tapering a portion of TMF. Additionally, novel directional couplers - $LP_{02}$ mode FMSCs - are demonstrated. Modeling, numerical calculation, fabrication, and characterization are described respectively. $LP_{11}$ mode FMSCs are fabricated using circular core TMF at the wavelength of 1064 nm and elliptical core TMF at 1550 nm. The modal properties in the waist of the coupler are calculated to find optimum initial condition to satisfy the phase-matching condition in the coupling region. SMF arm and TMF arm are prepared by way of pre-tapering and etching portions of TMF respectively. They are fused and pulled together to form a fused coupler using flame-brushing method. The coupling efficiency of 80% and the mode extinction of 20 dB are achievable in each case, and the couplers show high temperature-stability over the range of about 80 degrees. The operating bandwidth measures from several tens of nm to over 100 nm. Directional couplers that couple the $LP_{01}$ mode of SMF and the $LP_{02}$ mode of HMF are demonstrated for the first time. The $LP_{02}$ mode FMSCs are fabricated with circular core HMFs at the wavelength of 633 nm and 1550 nm respectively. Although the modeling and simulation schemes are similar to that of $LP_{11}$ mode FMSC, the fabrication condition of the $LP_{02}$ mode FMSC is more rigorous to suppress the unwanted mode coupling to $LP_{21}$ mode which is another higher-order mode guided in HMF. The coupling efficiency of 70% is achieved in each case and the mode extinction is measured to 13 dB at 633 nm and 8 dB at 1550 nm. The fabricated LP02 mode FMSC has potential application in broadband dispersion compensation using $LP_{02}$ mode if further research is followed to improve its mode extinction. The broad operating bandwidth and the unique function of proposed FMSCs will be useful in WDM optical communication and sensor application.

서지기타정보

서지기타정보
청구기호 {DPH 03011
형태사항 iv, 78 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Kwang-Yong Song
지도교수의 한글표기 : 김병윤
지도교수의 영문표기 : Byoung-Yoon Kim
수록잡지명 : "High performance fused-type mode selective coupler using elliptical core two-mode fiber at 1550 nm". IEEE photonics technology letters, v.14 no.4, pp.501-503 (2002)
학위논문 학위논문(박사) - 한국과학기술원 : 물리학과,
서지주기 참고문헌 : p. 75-78
주제 광섬유
광섬유 테이퍼
방향성 결합기
모드 결합
optical fiber
fiber taper
directional coupler
mode coupling
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