• 한국재료학회지
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• 제19권9호
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• pp.457-461
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• 2009

Recently, metal molding has become essential not only for automobile parts, but also mass production, and has greatly influenced production costs as well as the quality of products. Its surface has been treated by carburizing, nitriding and induction hardening, but these existing treatments cause considerable deformation and increase the expense of postprocessing after treatment; furthermore, these treatments cannot be easily applied to parts that requiring the hardening of only a certain section. This is because the treatment cannot heat the material homogeneously, nor can it heat all of it. Laser surface treatment was developed to overcome these disadvantages, and, when the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source. To estimate this, microstructural changes and hardness characteristics of three parts (the surface treatment part, heat affect zone, and parental material) are observed with the change of laser beam speed and surface temperature. Moreover, the depth of the hardened area is observed with the change of the laser beam speed and temperature.

• 한국정보통신학회논문지
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• 제5권3호
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• pp.581-590
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• 2001

본 연구는 광 전송 시스템에 레이저 다이오드의 안정되고 고정된 출력 파장의 광원을 제공하기 위한 것이다. 레이저 다이오드를 구동하기 위하여 안정된 정전류 회로를 설계하려 했으며, 레이저 다이오드 자체의 온도센서와 TEC(Thermo Electric Cooler)를 이용하여 레이저 다이오드 내부의 온도를 제어하는 온도 제어 회로를 구성하였다. 또한 광 출력에 Wavelength Locker글 이용하였다. 최종적으로 이들을 제어하기 위하여 A/D, D/A 컨버터와 마이크로 프로세서를 사용하였다.

• 전자공학회논문지D
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• 제34D권11호
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• pp.20-24
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• 1997

We have successfully fabricated high power (~20W) laser diode array, which are useful for pumping Nd:YAG lasers. The laser diode aray has 20 100.mu.m-wide cahnnels of which space was adjusted to 350.mu.m to improve thermal characteristics. And channel width is 100.mu.m. For an uncoated LD array, the output power of 15.66W has been obtained at 41A under quasi-CW operation, which results in about 0.42W/A slope efficiency. After aR(5%) and HR (95%) coatings on both facets, the output power was improved up to 21.18W at 40A under the same operation as above and the slope efficiency was 0.795W/A. On the other hand, by using a near field measurement system consisting of objective lens, eyepiece, CCD camera and image processing board, the typical near field patten of 1*20 LD array was observed.

• 한국광학회지
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• 제5권1호
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• pp.106-112
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• 1994

Fabry-Perot 모델을 사용하여 광폭 다이오우드 레이저(broad-area diode laser ; BLD)에 대한 주입-잠금을 분석하였다. 일반적인 단일띠 다이오우드 레이저의 경우와 다르게, 주입되는 광을 약간 경사지게 하는 BLD의 경우는 BLD가 하나의 포화 이득 증폭기로서 동작한다고 볼 수 있으며, BLD의 양면에서의 다중 반사의 의한 중첩으로써 출력된 광을 해석할 수 있다. 1차원 Gaussian 광의 중첩에 의한 근거리와 먼 거리 분포를 구하였다. 또한, 입사 광의 주파수가 변화될 때 출력 광의 각도 변화를 계산하여 대역폭 약 120 GHz에 0.022도/GHz 혹은 10.37도/nm의 값을 얻었다.

• 대한전자공학회논문지
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• 제17권2호
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• pp.10-14
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• 1980

본 논문에서는 DH-laser diode의 threshold current를 계산하기 위하여 2차고조파 왜곡 (se cond harmonic distortion)에 대해 Rate 방정식 (Rate-equation)을 동적상태와 정적상태 방정식으로 연릴하여 계산하였다. 특히 고조파 왜곡 ( )을 계산하는데 바이어스 전류 에 대하여 변조 전류 을 변조계수 m으로 놓고 (Jm=mJo)계산하여 주입전류 J가 Jth에서 2차 고조파 왜곡이 최대치를 가짐을 보여 ,이제까지 알려진 Jth조사 방법보다 간편하고 정확하게 조사할 수 있음을 제시하였다.

• 대한전자공학회논문지
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• 제17권6호
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• pp.72-77
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• 1980

본 논문에서는 optical feedback prebias control 회로상의 몇가지 일반적인 문제점들을 분석하고 이에 수반되는 회로 조정의 문제를 해결하기 위하여 LD simulation 회로를 제시하였다. 온도 시험에서 LD의 총 light power를 feedback loop에 사용하였을 때 0℃부터 36℃까지의 사이에서 1.5%의 light power 감소를 보였고 star coupler를 beam splitter로 1%정도를 분지, feedback loop에 사용한 결과 transmitter로서 좋은 전송 특성을 가짐을 관찰하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.76-77
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• 1998

In this paper, the authors have implemented a blood flow simulator and a blood flowmeter probe using self-mixing effect of the laser diode. The purpose of the blood simulator is to simulate microvascular blood flow in tissue. It consists of melinex film (thickness = $125{\mu}m$) which has similar optical characteristics to epidermis and porous polyethylene filter (Vyon, porosity 35%, mean pore size $50{\mu}m$, thickness=1 mm) which has similar optical characteristics to dermis. The blood flowmeter probe consists of laser diode(5 mW, 780 nm wavelength), CD lens(focal lenght 12 mm), current-to-voltage converter, highpass filter, and preamplifier. It doesn't need optical fiber, therefore, implementation of the probe is simpler than conventional probe using optical fiber.

• 센서학회지
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• 제20권1호
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• pp.53-57
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• 2011

We developed a small methane detection system because methane gas is used in many areas and is dangerous. The developed system consisted of LD(Laser Diode) tuned a wavelength of $1.65\;{\mu}m$, two mirrors to collect a laser beam, photo detector. It could detect methane gas at a long range and its sensitivity was 1.98 V/$CH_4%$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.9-12
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• 2001

Optical aligning process to archive the maximum optical coupling is crucial in many optical device manufacturing line such as laser diode module. Due to the three-dimensional nature of housing module and the aligning process for laser diode coupler, large amount of the manufacturing time, typically ranging from tens of minutes to an hour has to be devoted to the aligning process alone. In this thesis, we propose a new optical aligning process that employee a two-pass algorithm: coarse-to-fine search. Coarse search is a kind of blind search that finds the candidate region where the maximum optical coupling might mostly occur, followed by a fine searching that finds the maximum within the candidate region. The algorithm has been tested on 50 samples of cam-type laser diode modules, and the experimental results are analyzed in terms of aligning time and coupling efficiency.

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.698-703
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• 2016

We report a new all-optical flip-flop (AOFF) with a quite simple structure, using optical beating in an injection-locked Fabry-Perot laser diode (FP-LD) with optical bistability. While conventional AOFF methods using an injection-locked FP-LD require additional devices such as secondary FP-LDs or polarization controllers for reset operation, the proposed method can be implemented using only a single commercially available FP-LD with set and reset signals. The optical beating induces intensity fluctuations inside the FP-LD, and releases the locking state to the reset state. Even though we demonstrated the AOFF at 100 Mbit/s, we expect that its operation rate could extend to 10 Gbit/s, according to the limit of the FP-LD's frequency response.