서지주요정보
외부 공진기형과 상호 결합형 레이저 다이오드의 특성 연구 = Characteristics of external-cavity type and mutually-coupled type laser diodes
서명 / 저자 외부 공진기형과 상호 결합형 레이저 다이오드의 특성 연구 = Characteristics of external-cavity type and mutually-coupled type laser diodes / 신윤섭.
저자명 신윤섭 ; Shin, Yun-Sup
발행사항 [대전 : 한국과학기술원, 2000].
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소장정보

등록번호

8010768

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 00011

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초록정보

External cavity laser diodes (ECLDs) have attracted much attention because they have considerably narrow linewidth and tunable single frequency output, and have been widely used in many applications including coherent communications, interferometric sensors, and spectroscopy. In an usual ECLD, dielectric anti-reflection (AR) coating on the facet of a laser diode is frequently executed for strong external feedback. To obtain the wide continuous tuning range without mode hopping in ECLD, the pivot point of the external reflector should be selected carefully. In this thesis, two simple, but reliable, methods for evaluating the linewidth enhancement factor, α, value without modifying the laser configuration of conventional external cavity were suggested and demonstrated using the near infrared (785 nm) single mode ECLD. The unique dynamical characteristics of ECLD such as frequency tuning, spectral linewidth, FM noise, and stability problem result from the existence of the linewidth enhancement factor α of the LD. Consequently, it is very important to know the precise value of α to understand dynamics of the ECLD systems. In the first method of current scanning, the frequency tuning curve of ECLD as a function of injection current was used to evaluate the α value. We introduced a simple model which yields a linear relationship between the injection current and the phase shift of an incident wave after one round trip in the external cavity. With this assumption, experimental results like a multi-stability property or unmeasured wavelength regions could have been explained and the internal parameters of the solitary LD, α and $r_{int}$ were determined. On the other hand, in the second method of reflectivity scanning, the external feedback intensity was scanned to control the effective reflectivity of ECLD. The change of the external feedback intensity was accomplished by adjusting the rotation angle of a half wave plate (HWP) which was inserted in the external cavity. From the frequency tuning curve of ECLD as a function of the external feedback intensity, α and $r_{int}$ of the solitary LD were determined again. These values had worse statistical errors than those of the current scanning method due to the inaccuracy of reading the polarization angle of the HWP, but reasonably matched well to the previous result of the current scanning method. The values of α and $r_{int}$ of the both methods agreed with previously reported values. The injection locking method and the mutual coupling method have been actively studied in many laboratories to satisfy the need of large output power and multiple beams of same wavelength in the application field of LD and to reveal the mutual-effect of coupled LDs. Until now, only weak and symmetrical coupling systems have been tried in experiment to avoid chaotic output characteristics which cannot be controlled. Several types of strongly coupled system have been tested to obtain the stable and synchronized output beam. In the directly coupled case, two wavelengths of LDs were gone to close to each other but failed to reach to the perfect synchronization. A new structure consisted of two mutually coupled LDs in the cross shape was proposed and shown to make the perfectly synchronized output. Since this structure has asymmetric characteristics by beam splitter, it shows the injection locking properties even without any optical isolator. In this structure, outputs of LD were coherently added and exhibited stable characteristics, e.g., broad locking range, insensitivity to unwanted weak outer feedback. This strongly coupled structure is expected to be a new candidate for a light source of the research into the secret code technology in optical communication fields, spectroscopy, and so on.

서지기타정보

서지기타정보
청구기호 {DPH 00011
형태사항 xi, 131 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 : A, 레이저 다이오드의 율 방정식. - B, Langevin 잡음원(noise source)
저자명의 영문표기 : Yun-Sup Shin
지도교수의 한글표기 : 남창희
지도교수의 영문표기 : Chang-Hee Nam
학위논문 학위논문(박사) - 한국과학기술원 : 물리학과,
서지주기 참고문헌 : p. 127-131
주제 외부 공진기형 레이저 다이오드
선폭 증가 인자
회전축
주입 잠금
상호 결합
External cavity laser diode
Lonewidth enhancement factor
Pivot point
Injection locking
Mutual coupling
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