• 한국광학회지
• /
• 제9권3호
• /
• pp.186-190
• /
• 1998

직경이 10mm인 유리관의 외벽을 금으로 코팅하여 반사체로 사용되고 최대 출력이 140W인 레이저 다이오드바 (laser diode bar) 3개를 여기 광원으로 이용한 고출력 Nd:YAG 레이저를 설계 제작하였다. 레이저봉의 지름은 6mmdlqu 길이는 130mm이다. 투과율이 11%인 출력경과 전반사경을 사경하여 선형공진기를 구성하고 연속발전시켰을 때 약 130W의 Nd:YNG 레이저 연속출력을 얻었으며 이 때 측정된 기울기 43%, 광변환 효율은 31%에 도달하였다. 레이저빔의 빔질인자(beam quality factor)M2는 최대 다이오드 츨력에서 약85로 관측되었으며 레이저 발진시에 측정한 열렌즈 초점거리의 역수와 여기광의 출력비는 5.3∼7.4D/kWpump 이었다.

• Journal of Mechanical Science and Technology
• /
• 제17권1호
• /
• pp.139-145
• /
• 2003

Diode laser sensor is conducted to measure the gas temperature in the liquid-gas 2-phase counter flow flame. C$\_$10/H/ sub 22/ and city gas were used as liquid fuel and gas fuel, respectively. Two vibrational overtones of H$_2$O were selected and measurements were carried out in the spray flame region stabilized the above gaseous premixed flame. The path-averaged temperature measurement using diode laser absorption method succeeded in the liquid fuel combustion environment regardless of droplets of wide range diameter. The path-averaged temperature measured in the post flame of liquid-gas 2-phase counter flow flame showed qualitative reliable results. The successful demonstration of time series temperature measurement in the liquid-gas 2-phase counter flow flame gave us motivation of trying to establish the effective control system in practical combustion system. These results demonstrated the ability of real-time feedback from combustor inside using the non-intrusive measurement as well as the possibility of application to practical combustion system. Failure case due to influence of spray flame was also discussed.

• 한국전기전자재료학회논문지
• /
• 제22권3호
• /
• pp.248-251
• /
• 2009

We have investigated the effect of the quality of 1.3 um distributed feed back laser diode (DFB-LD) on the design of anti-reflection (AR) coatings. Optimal condition of AR coating to prevent internal feedback from both facets and reduce the reflection-induced intensity noise of laser diode was simulated with Macleod Simulator. Coating materials used in this work were ${Ti_3}{O_5}$ and $SiO_2$, of which design thickness were 105 nm and 165 nm, respectively. AR coating films were deposited by Ion-Assisted Deposition system. The electrical and optical properties of 1.3 um laser diode were characterized by Bar tester and Chip tester. Threshold current and slop-efficiency of DFB-LD were 27.56 mA 0.302 W/A. Far field pattern and wavelength of DFB-LD were $22.3^{\circ}(Horizontal){\times}24.4^{\circ}$ (Vertical), 1313.8 nm, respectively.

• ETRI Journal
• /
• 제32권2호
• /
• pp.339-341
• /
• 2010

The fundamental transverse mode lasing of a hybrid laser diode is a prerequisite for efficient coupling to a single-mode silicon waveguide, which is necessary for a wavelength-division multiplexing silicon interconnection. We investigate the lasing mode profile for a hybrid laser diode consisting of silicon slab and InP/InGaAsP deep ridge waveguides. When the thickness of the top silicon is 220 nm, the fundamental transverse mode is lasing in spite of the wide waveguide width of $3.7{\mu}m$. The threshold current is 40 mA, and the maximum output power is 5 mW under CW current operation. In the case of a thick top silicon layer (1 ${\mu}m$), the higher modes are lasing. There is no significant difference in the thermal resistance of the two devices.

• 센서학회지
• /
• 제3권2호
• /
• pp.57-64
• /
• 1994

레이저 다이오드의 자기혼합 효과를 이용한 조직혈류측정을 위한 기초연구를 하였다. 이동물체로 인한 레이저 도플러 신호를 자기혼합 효과에 의해 검출하였으며, 피검자의 인지로부터 비관혈적으로 조직의 혈류 변화를 측정할 수 있었다. 이동 물체의 이동속도가 변함에 따라 자기혼합 효과에 의한 도플러 편이 주파수는 선형적으로 변하였으며, in-vivo 실험의 인지에서 측정된 토플러 신호는 운동후의 주파수가 운동전의 주파수 보다 높았으며, 이는 운동생리학적인 결과와도 일치하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.354-359
• /
• 1994

On-line process control equipment for CO $_{2}$ laser cutting is unavailable for industrial application. The major part of the industrial cutting machines are regulated off-line by highly educated engineers. The quality inspection of the sample is visual and referred to different quality scales. Due to lack of automation potential laser users hesitate to implement the cutting method. The first step toward an automation of the process is development of a process monitoring system and the research is concentrated on the area of on-line quality detection during CO $_{2}$ laser cutting. The method bases on the detection of the emitted light from the cut front by photo diode. the signal from photo diode has been undertaken from Fourier analysis and statistical analysis. As a result, it is possible to estimate striation pattern according to beam travel speed.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
• /
• pp.338-338
• /
• 2011

최근 FPD (Flat Pannel Display) 시장이 커짐에 따라 고효율, 저비용 제작 공정이 화두로 떠오르고 있다. ELA (Excimer Laser Annenling)을 이용한 LTPS (Low Temperature Poly Silicon) 공정은 mobility와 전류 점멸비 등에서 장점을 가지지만, 고비용, 대면적과 short-range에서 uniformity가 어렵다는 단점이 있다. 이를 극복하기 위한 방법으로 dLTA (diode Laser Thermal Annealing) 공정에 대한 연구가 진행되고 있다. 본 연구에서는 Flexible Display을 만들기 위한 방법으로 dLTA 공정을 진행하였다. 이 방법은 PI (Poly imide) 기판 위에 a-Si을 ICP CVD로 증착시킨 후, Diode Laser (980 nm)를 이용한 annealing을 통하여 a-Si이 poly-Si으로 결정화가 되는 것을 확인하였고, 에너지 조사량에 따른 grain boundary와 grain size을 통하여 비교 분석하였다. 실험 결과 ELA 공정을 이용한 것과 버금가는 실험 결과를 얻을 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권5호
• /
• pp.222-227
• /
• 2002

Recently, the research on artificial retina for the blind is active. In this paper a new optical link method for the retinal prosthesis is proposed. Laser diode system was chosen to transfer image into the eye in this project and the new optical system was designed and evaluated. The use of laser diode array in artificial retina system makes system simple for lack of signal processing part inside of the eyeball. Designed optical system is enough to focus laser diode array on photodiode array in 20$\times$20 application.

• Journal of the Optical Society of Korea
• /
• 제17권4호
• /
• pp.312-316
• /
• 2013

A novel fiber-optic sensor system is suggested in which fiber Bragg grating sensors are demodulated by a wavelength-sweeping fiber laser source and a spectrometer. The spectrometer consists of a diffraction grating and a 512-pixel photo-diode array. The reflected Bragg wavelength information is transformed into spatial intensity distribution on the photo-diode array. The peak locations linearly correspond to the Bragg wavelengths, regardless of the nonlinearities in the wavelength tuning mechanism of the fiber laser. The high power density of the fiber laser enables obtaining high signal-to-noise ratio outputs. The improved demodulation characteristics were experimentally demonstrated with a fiber Bragg grating sensor array with 5 gratings. The sensor outputs were in much more linear fashion compared with the conventional tunable band-pass filter demodulation. Also it showed advantages in signal processing, due to the high level of photo-diode array signals, over the broadband light source system, especially in measurement of fast varying dynamic physical quantities.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
• /
• pp.1078-1080
• /
• 1999

A laser pulse generator which consists of charging resistor, energy storage capacitor laser diode, and switching elements was designed in order to generate 15ns, 20W laser pulses. And the effects of performances of SCR and FET as switching elements are compared. When SCR is used, the SCR's low maximum voltage makes the circuit so complicated, and when FET is used, the FET needs the special sate driver which improves the FET's operation.