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Dissipative Soliton Mode-locked All-fiber Laser with a Broad Spectral Bandwidth
박설원,염동일 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11
We demonstrate an all-fiber dissipative soliton fiber laser (DSFL) with a very broad spectralbandwidth by optimizing the cavity design of the fiber laser. Two different cavity schemes ofthe DSFL with simple cavity structures were built by employing a hybrid component, and theirproperties were investigated while varying the net cavity dispersion of the laser. By optimizing thecavity dispersion of the fiber laser, we achieved a DSFL that stably deliver linear chirped pulses witha pulse duration of 912.5 fs at a repetition rate of 52.2 MHz without additional pulse compression. The measured spectral bandwidth of the laser was 68 nm, which is the largest value ever reportedfor Er-doped DSFL oscillators.
정환승,염동일 한국광학회 2017 Current Optics and Photonics Vol.1 No.3
We report a passive Q-switching of an all-fiber erbium-doped fiber laser delivering high pulse energyby using a high quality single-walled carbon nanotube saturable absorber (SWCNT-SA). A side-polishedfiber coated with the SWCNT is employed as an in-line SA for evanescent wave interaction between theincident light and the SWCNT. This lateral interaction scheme enables a stable Q-switched fiber laser thatgenerates high pulse energy. The central wavelength of the Q-switched pulse laser was measured as 1560nm. A repetition rate frequency of the Q-switched laser is controlled from 78 kHz to 190 kHz by adjustingthe applied pump power from 124 mW to 790 mW. The variation of pulse energy from 51 nJ to 270nJ is also observed as increasing the pump power. The pulse energy of 270 nJ achieved at maximumpump power is 3 times larger than those reported in Q-switched all-fiber lasers using a SWCNT-SA. Thetunable behaviors in pulse duration, pulse repetition rate, and pulse energy as a function of pump powerare reported, and are well matched with theoretical expectation.
포화 흡수체의 투과변조깊이 조절을 통한 다양한 펄스상태 조작 방법에 관한 전산 모사
진진화,염동일,김병윤 한국광학회 2017 한국광학회지 Vol.28 No.6
In this paper, we conduct a simulation of manipulating various pulsed laser operations through tuning the modulation depthof the saturable absorber in a laser cavity. The research, showing that various pulsed operations could be manipulated fromQ-switching through Q-switched mode locking to mode locking by tuning the modulation depth of the saturable absorber in acavity, has been studied by experimental means. We conduct a simulation with the Haus master equation to verify that theseexperimental results are consistent with expectations from theory. The time dependence of the gain was considered to expressQ-switching fluctuation through applying a rate equation with the Haus master equation. Laser operation was manipulated frommode locking through Q-switched mode locking to Q-switching as modulation depth was increased, and this result agreed wellwith the theoretical expectation.
조영권,염동일,김기홍 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.2
We numerically investigate the evolution of a dissipative soliton in erbium-doped fiber (EDF) mode-locked lasers operating in the net normal cavity dispersion regime. The pulse evolution in the laser cavity is analyzed by using a simulation based on the generalized nonlinear Schr?inger equation, including the gain medium, the saturable absorber and the bandpass filter for efficient laser mode-locking. The analysis particularly focused on the function of bandpass filtering, which played a crucial role in balancing the pulse evolution against the dispersive propagation in a normal dispersion waveguide. The characteristics of the laser output spectra are analyzed for various bandwidths of the filter with other parameters fixed. As a result, we obtained a maximum spectral bandwidth of 20 nm in the laser output for a 13-nm bandwidth of the filter; the pulse duration was about 200 fs. Our results imply the possibility for realizing sub-picosecond (ps) pulse generation in a dissipative soliton laser system possessing a large net normal cavity dispersion.
모드 잠금된 펄스 레이저와 연속 발진하는 반도체 레이저를 이용한 합주파수 생성
김현학,박남훈,염동일,차명식,문한섭,Kim, Hyunhak,Park, Nam Hun,Yeom, Dong-Il,Cha, Myoungsik,Moon, Han Seb 한국광학회 2021 한국광학회지 Vol.32 No.2
본 연구에서는 모드 잠금된 ps-펄스 광섬유 레이저와 연속 발진하는 좁은 선폭의 반도체 레이저를 이용하여 주기적 분극반전된 LiNbO3(periodically poled lithium niobate; PPLN) 결정에서 합주파수 생성 연구를 수행하였다. 모드 잠금된 펄스 레이저는 중심 파장이 1560.7 nm이고 스펙트럼의 폭은 약 1.1 nm이며, 연속 발진 반도체 레이저는 중심 파장이 1551 nm이고 스펙트럼의 폭은 약 6 MHz로 동작한다. 합주파수 생성을 효과적으로 수행하기 위해서 하나의 단일 모드 광섬유를 이용하여 PPLN 결정 내부에서 두 펌프 광원을 공간적으로 완전히 중첩하였다. 모드 잠금된 펄스 레이저와 좁은 선폭의 연속발진 반도체 레이저에 의해서 모드 잠금된 펄스 형태의 778 nm인 합주파수 생성을 스펙트럼과 시간적인 변화로 확인하였다. 본 연구 결과는 주파수 제어가 가능한 광주파수 빗(optical frequency comb)을 이용한 광주파수 측정 및 고분해 레이저 분광 연구 등 다양하게 응용될 수 있을 것으로 기대된다. We have experimentally demonstrated sum-frequency generation (SFG) in a periodically poled lithium niobate (PPLN) crystal, using a mode-locked picosecond-pulsed fiber laser and a continuous-wave (CW) diode laser with a narrow linewidth. The mode-locked fiber laser had a center wavelength of 1560.7 nm and a spectral width of 1.1 nm, and the CW diode laser had a center wavelength of 1551.0 nm and a spectral width of 6 MHz. To effectively realize SFG, both of the spatial modes of the two lasers were made to overlap in the PPLN crystal by using a single-mode optical fiber. The pulse-mode SFG with pulsed- and CW-mode lasers was successfully observed in the spectral and time domains. These results are expected to be applicable in various ways, such as optical frequency measurement and high-resolution laser spectroscopy studies using optical frequency combs.