• 전자공학회논문지A
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• 제32A권10호
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• pp.43-50
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• 1995

A laser diode(LD) structure consisting of a single 150$\AA$ $Al_{0.07}$Ga$_{0.93}$As quantum well active region operating at ${\lambda}$=809nm, cladded with an AlGaAs graded-index separate confinement heterostructure, has bes been grown by MOCVD. Temperature coefficient of wavelength is approximately 0.2nm $^{\circ}C$ for the diode. The active aperture consists of five emitters separated from each other by means of SiO$_{2}$ deposition and stripe formation, which creates insulating regions that channel the current to 100-$\mu$m-wide stripes placed on 450-$\mu$m centers. From a typical uncoated LD, the output power of 0.8W has been obtained at a 1$\mu$s, 1kHz pulsed current level of 2.0$\AA$, which results in about 64% external quantum efficiency. The threshold current density is 736A/cm$^{2}$ for the case of 500$\mu$m cavity length LD's. The measure of an internal quantum efficiency was 75.8% and the internal loss 4.83$cm^{-1}$ . Finally, 3.1W output power has been obtained at a 1$\mu$s, 1kHz pulsed current level of 9A from the 500$\mu$m-aperture LD array with 460-$\mu$m- cavity length.

• 대한의용생체공학회:의공학회지
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• 제28권2호
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• pp.169-173
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• 2007

During laser irradiation, mechanically deformed cartilage undergoes a temperature dependent phase transformation resulting in accelerated stress relaxation. Clinically, laser-assisted cartilage reshaping may be used to recreate the underlying cartilaginous framework in structures such as ear, larynx, trachea, and nose. Therefore, research and identification of the biophysical transformations in cartilage accompanying laser heating are valuable to identify critical laser dosimetry and phase transformation of cartilage for many clinical applications. quasi-elastic light scattering was investigated using Ho : YAG laser $(\lambda=2.12{\mu}m\;;\;t_p\sim450{\mu}s)$ and Nd:YAG Laser $(\lambda=1.32{\mu}m\;;\;t_p\sim700{\mu}s)$ for heating sources and He : Ne $(\lambda=632.8nm)$ laser, high-power diode pumped laser $(\lambda=532nm)$, and Ti : $Al_2O_3$ femtosecond laser $(\lambda=850nm)$ for light scattering sources. A spectrometer and infrared radiometric sensor were used to monitor the backscattered light spectrum and transient temperature changes from cartilage following laser irradiation. Analysis of the optical, thermal, and quasi-elastic light scattering properties may indicate internal dynamics of proteoglycan movement within the cartilage framework during laser irradiation.

• Current Optics and Photonics
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• 제7권1호
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• pp.90-96
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• 2023

We numerically solve the nonlinear Schrödinger equation for pulse propagation in a passively mode-locked Yb:KGW laser. The soliton-like pulse formation as a result of balanced negative group-delay dispersion (GDD) and nonlinear self-phase modulation is analyzed. The cavity design and optical parameters of a previously reported high-power Yb:KGW laser were adopted to compare the simulation results with experimental results. The pulse duration and energy obtained by varying the small-signal gain or GDD reproduce the overall tendency observed in the experiments, demonstrating the reliability and accuracy of the model simulation and the optical parameters.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.314-320
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• 1998

In this study, we have investigated crystallization properties of $Te_x(Sb_{85}Ge_{15})_{100-x}$ (x=0.3, 0.5, 1.0) thin films prepared by thermal evaporation. The change of reflectance according to phase change from amorphous to crystalline phases with annealing and exposure of diode laser is measured b the n&k analyzer and the surface morphology between amorphous and crystalline phase is analyzed by SEM and AFM. The difference in reflectance($\DeltaR$) between amorphous and crystalline phase appears approximately 20% at the diode laser wavelength, 780nm in all prepared films. Especially, the reflectance difference,$\DeltaR$ comes up to about 30% in $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film. Also, amorphous-to-crystalline phase change is observed in all prepared films. As a result of the measurement of the reflectance using diode laser, the reflectance is increased in proportion to the laser power and exposure time in all films. As a result of observing each film with the SEM and AFM, the surface morphology of the annealed and the exposed films are evidently increased than those of as-deposited films. The fast crystallization is occurred by increasing in Te content. Therefore, we conclude that the $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ and $Te_1(Sb_{85}Ge_{15})_{99}$ thin films can be evaluated as an attractive optical recording medium with high contast ratio and fast erasing time due to crystallization.

• ETRI Journal
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• 제23권3호
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• pp.97-105
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• 2001

$1.6\;{\mu}m$ emission originated from $Pr^{3+}:\;(^3F_3,\;^3F_4)\;{\longrightarrow}\;^3H_4$ transition in $Pr^{3+}-\;and\;Pr^{3+}/Er^{3+}$-doped selenide glasses was investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and fullwidth at half-maximum of the fluorescent emission are ~1650nm and 120nm, respectively. A moderate lifetime of the thermally coupled upper manifolds of ${\sim}212{\pm}10{\mu}s$ together with a high stimulated emission cross-section of ${\sim}(3{\pm}1){\times}10^{-20}\;cm^2$ promises to be useful for $1.6{\mu}m$ band fiber-optic amplifiers that can be pumped with an existing high-power 1480 nm laser diode. Codoping $Er^{3+}$ enhances the emission intensity by way of a nonradiative $Er^{3+}:\;^4I_{13/2}\;{\longrightarrow}\;Pr^{3+}:\;(^3F_3,\;^3F_4)$ energy transfer. The Dexter model based on the spectral overlap between donor emission and acceptor absorption describes well the energy transfer from $Er^{3+}$ to $Pr^{3+}$ in these glasses. Also discussed in this paper are major transmission loss mechanisms of a selenide glass optical fiber.

• 구강회복응용과학지
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• 제32권2호
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• pp.117-122
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• 2016

목적: 치은 미백은 치과치료의 목적으로 심미적 장애를 위한 치료에 가깝다. 기존의 치은미백술은 고출력 다이오드 레이저를 이용하여 박피술에 의한 치료를 했왔다. 그러나 이러한 치료법은 시술 후 감염 및 통증에서 자유로울 수 없기에, 우리는 저출력 LED 레이저를 이용하여 치은미백술을 진행하고자 하였다. 연구 재료 및 방법: 돼지고기 표면에 레이저를 조사하여 출력전력, 온도변화, 피부 변성 등의 안정성을 측정하였다. 15 - 20 kg 비글의 구강내 점막 색소에 비손 365 nm LED 레이저를 15분씩, 1 - 2주간 1, 2회씩 각각 조사하였다. 헤마토실린-에오신 염색을 통하여 색소의 손실여부를 확인하였다. 결과: 365 nm LED 레이저 조사 부위의 멜라닌 색소가 줄어드는 것을 확인 할 수 있었다. 결론: 본 연구에서 제시하는 365 nm LED 레이저는 수술적 기술 및 다이오드 레이저를 이용한 탈색화 효과를 대처 할 수 있을 것이라고 사료 된다.

• 정보와 통신
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• 제28권12호
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• pp.50-60
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• 2011

Visible light communication(VLC) is one type of short-range, optical, and wireless communication system utilizing light emitting diode(LED) and laser diode(LD) as optical source. In a VLC system, visible light is used as a transmission medium and used to illuminate. Using VLC has a lot of advantages: it is harmless to human body; it transmits with high power, and it has excellent security, a high data rate, and a license free frequency band. With such a unique blend of communication and illumination in one system, the most common application would be an indoor environment. We aim at reviewing key issues in VLC network such as : FOV(field of view), priority MAC, cooperative MAC, link switching, LED-ID technique, cell site diversity, and link recovery.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.35-36
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• 2006

In Nd:YAG laser welding, evaluation methods of welding flaw are various. But, the method due to fume shape is difficult to classification of welding flaw. The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. At the present time, some methods are studied for measurement of fume shape by using high-speed camera and photo diode. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. In this study, fume shape was measured by infrared thermal camera that is non-contact/non-destructive thermal measurement equipment through change of laser generating power, speed, focus. Weld was performed on bead-on method. Measurement results are compared as two equipments. Here, two results are composed of measurement results of fume quantities due to fume shape by infrared thermal camera and inspection results of weld bead include weld flaws by ultrasonic inspector.

• 한국재료학회지
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• 제21권7호
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• pp.364-370
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• 2011

Currently, there are two main issues regarding the development of core technologies in the automotive industry: the development of environmentally friendly vehicles and securing a high level of safety in the event of an accident. As part of the efforts to address these issues, research into alternative materials and new car body manufacturing and assembly technologies is necessary, and this has been carried out mainly by the automotive industries. Large press molds for producing car body parts are made of cast iron. With the increase of automobile production and various changes of design, the press forming process of car body parts has become more difficult. In the case of large press molds, high hardness and abrasive resistance are needed. To overcome these problems, we attempted to develop a combined heat treatment process consisting of local laser heat treatment followed by plasma nitriding, and evaluated the characteristics of the proposed heat treatment method. From the results of the experiments, it has been shown that the maximum surface hardness is 864 Hv by the laser heat treatment, 953 Hv by the plasma nitriding, and 1,094 Hv by the combined heat treatment. It is anticipated that the suggested combined heat treatment can be used to evaluate the durability of press mold.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.647-650
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• 2006

Low temperature polycrystalline silicon (LTPS) technology using a high power laser have been widely applied to thin film transistors (TFTs) for liquid crystal, organic light emitting diode (OLED) display, driver circuit for system on glass (SOG) and static random access memory (SRAM). Recently, the semiconductor industry is continuing its quest to create even more powerful CPU and memory chips. This requires increasing of individual device speed through the continual reduction of the minimum size of device features and increasing of device density on the chip. Moreover, the flat panel display industry also need to be brighter, with richer more vivid color, wider viewing angle, have faster video capability and be more durable at lower cost. Kornic Systems Co., Ltd. developed the $KORONA^{TM}$ LTP/GLTP series - an innovative production tool for fabricating flat panel displays and semiconductor devices - to meet these growing market demands and advance the volume production capabilities of flat panel displays and semiconductor industry. The $KORONA^{TM}\;LTP/GLTP$ series using DPSS laser and XeCl excimer laser is designed for the new generation of the wafer & FPD glass annealing processing equipment combining advanced low temperature poly-silicon (LTPS) crystallization technology and object-oriented software architecture with a semistandard graphical user interface (GUI). These leading edge systems show the superior annealing ability to the conventional other method. The $KORONA^{TM}\;LTP/GLTP$ series provides technical and economical benefits of advanced annealing solution to semiconductor and FPD production performance with an exceptional level of productivity. High throughput, low cost of ownership and optimized system efficiency brings the highest yield and lowest cost per wafer/glass on the annealing market.