• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.97-103
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• 2006

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.111-114
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• 2001

Optical transmitter and receiver are the essential components for optical communication. For these components, butterfly type packages are used which are comprised of metal housing, multilayer ceramic inserts, lead and window. In this study, 2.5 Gbps DFB(Distributed -Feedback) LD(Laser Diode) package was fabricated and characterized. Metal housing showed good thermal conductivity (200W/mK) and well matched TCE(6.7ppm/K) with GaAs chip. Ceramic inserts also showed good VSWR(Voltage Standing Wave Ratio) characteristics(<2.0). By brazing technology, all the elements were combined and sealed. RF characteristics of the package mounted on the PWB was also tested.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.19-21
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• 2007

디지털용 Uncooled DFB 레이저 다이오드를 이용하여 광대역 아날로그 피드포워드 광송신기를 제작하였다. 광송신기의 상호변조왜곡 성분 및 잡음성분을 제거하기 위해 광 피드포워드 보상기법을 사용하였으며, 다중서비스를 위해 $2.05{\sim}2.60$ GHz(550 MHz)에서 상호 변조왜곡 성분이 10 dB 이상 억제되었고, 상대강도잡음은 1.5 dB 이상 억제되었다. 2.3 GHz 에서 3 차 상호변조왜곡성분이 21.3 dB, SFDR 이 7.11 dB 향상된 결과를 얻었다. 또한 단일 모드 광섬유 전송 실험을 통해 전송길이에 따른 3 차 상호변호 왜곡성분의 크기 변화를 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.685-689
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• 2003

오늘날 급격히 증가되고 있는 광 대역 멀티미디어 서비스, 초고속 대용량 인터넷 서비스 등을 가입자에게 제공하기 위해서는 광 가입자망 기반의 네트워크 구성이 필수적이다. 최근 효율적이고 경제적인 광 가입자망 구축을 위한 기술들이 빠르게 개발됨에 따라 효율적인 네트워크 구성이 가능하게 되었다. 이중 대표적인 기술로 PON(Passive Optical Network)을 이용하여 ONN(Optical Network Unit)를 공유하는 방식의 WDM(Wavelength Division Multiplexing)-PON 기술이 있으며, 이를 이용한 FTTH(Fiber to The Home)시스템에 대한 개발이 활발히 이루어지고 있다. 본 논문에서는 100BASE-TX 및 1000BASE-T Ethernet 신호를 입력받아 파장별 DFB-LD에 직전 변조하는 방식을 사용하여 WDM-PON 시스템에 적용할 수 있는 광 송수신기를 설계하고 이를 구현하였다.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.12-21
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• 2012

Simultaneous measurements of oxygen concentration and temperature using diode laser in the combustion environment are successfully accomplished. A single DFB type diode laser of 760 nm line centre frequency is used and the scanned-wavelength direct absorption spectroscopy method and wavelength modulation spectroscopy method are applied to measure absorption signals below 793 K temperature region. The experimental results show that oxygen concentration are measured within 1% accuracy and temperature are measured within 5% accuracy. This new method of simultaneous measurements of concentration and temperature with a single diode laser shows a great promise.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.475-477
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• 2005

We simulated 3rd order intermodulation distortion (IMD3) induced Carrier-to-Intermodulation Ratio (CIR) of laser diodes over a wide range of optical modulation index, and compared the results with commercial IMD3 induced CIR specification such as Composite Triple Beat (CTB) of DFB laser transmitter for CATV networks. It shows that the simulation results are in good agreement with the CATV CTB specification within 3dB margin. The results can be used to predict IMD3 induced CIR performance for various analog optical transmission systems with given optical modulation index and the number of transmission channels.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.111-118
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• 2006

A hybrid focus method with multiple laser slits is newly proposed for the measurement of surface morphology with depth discontinuity, and it is based on the integration of DFB and DFF. Rough depth information is estimated through calibration tables which are constructed by DFD with multiple laser slits, and then DFF is applied to only each specific depth range using the rough depth information resulting from DFD. The proposed hybrid method gives more accurate results than DFD and DFF, and faster measurement than DFF in the vicinity of depth discontinuity Its performance is verified through experiments of calibration blocks with sharp depth discontinuity.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.45-51
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• 1993

An erbium doped fiber amplifier(EDFA) pumped by aingle 1.48$\mu$m LD was fabricated, and its gain and noise characteristics were measured. As a signal source, 1548 nm wavelength DFB LD was used. The small signal net gain of the EDFA module was 21.8 dB with maximum gain coefficient 0.7dB/mW for the erbium fiber length of 17.6 m, the pump power of 58 mW, and an input signal power of -25 dBm, respectively. The saturation power of the EDFA was 1 dBm for the input signal power of -5 dBm and the noise figure, measured by using an optical spectrum analyzer, was 5.8 dB for the input signal power of -40 dBm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.446-449
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• 2003

최근에 VOD, HDTV, 라이브 스트리밍 등의 서비스가 늘어나면서 가입자들은 광대역 서비스를 요구하고 있다. 이를 가입자에게 제공하기 위해서는 광대역폭을 지원할 수 있는 FITH(Fiber to The Home)의 실현이 필수적이며, FTTH의 고비용과 설비 문제를 해결하기 위한 대안으로 PON(Passive Optical Network)이 부상하고 있다. PON은 네트워크를 시스템이 아닌 소자로 구성해, 일정거리까지는 하나의 광 회선을 설치하고 스플리터를 중심으로 여러 개로 회선을 분배하는 것이다. 이 또한 스플리터의 한계로 분배할 수 있는 회선이 제한적이며, 이를 해결하기 위한 방법으로 WDM(Wave-length Division Multiplexing)-PON이 고려되고 있다. 이에 본 논문에서는 WDM-PON에 적용할 수 있는 Ethernet 기반의 광 송수신 채널 유닛을 설계하였다. 채널 유닛은 1000BASE-T Ethernet 신호를 입력받아 파장별 DFB-LD에 직접 변조하는 방식을 사용하여 구현하였다.

• Journal of Sensor Science and Technology
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• v.20 no.1
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• pp.8-13
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• 2011

We present measurements of the Brillouin frequency shift in an optical fiber using a 1550 nm distributed feedback laser diode(DFB-LD) as a light source. By modulating the probe light with an electro-optic modulator, we confirm the stimulated Brillouin gain spectrum(BGS) and spontaneous BGS using the coherent detection method. We also confirm the applicability of the technique to distributed temperature sensors that measure the change in Brillouin frequency shift due to temperature variations.