• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.217-225
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• 2003

In this paper, in order to investigate the near field distribution characteristic of the Loop Antenna we simulated and measured the near field of a Loop Antenna using optical electric-field sensor in a large Chamber(8.5 m x 7 m x 7 m). The simulation methods were used MoM for frequency domain and FDTD for time domain. From the analysis results, it can be seen that the simulation and measurement results are very aggregated, and the optical electric-field sensor is a certificate of validity. In frequency domain, in case of the optical sensor with vertical polarization is located above the near vertical line of the Loop Antenna the signal strength level is more 15 ㏈ than with horizontal polarization. But in case of the optical sensor located above horizontal line of the Loop Antenna, signal strength level is not different. And, in the time domain, although input signal is positive, in the case of the optical sensor with vertical polarization is located above horizontal line of the Loop Antenna, it can be seen that the received pulse shape is negative.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.35-43
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• 1999

We propose and analyze novel optical thyristor which can be used in free-space optical interconnection(FSOI). Novel optical thyristors are fully depleted optical thyristors(DOTs) using bottom mirror and/or multiple quantum wells (MQW), thereby its switching characteristics can be improved significantly. We obtain switching characteristics using coupled junction model associated with current oriented method. Emission characteristics of the DOT are obtained using thin film characteristic matrix and van Roosbroeck-Shockley relation. Compared to the performance using conventional DOT, the optical switching energy is decreased by a factor of 0.43 and the bit-rate is increased by a factor of 1.61 when the DOT with MQW and bottom mirror is employed for FSOI.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1515-1518
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• 2007

We demonstrate a high color gamut liquid crystal display (LCD) system (>100 %) by using a precompensated tri-chromatic LED-backlight module over a temperature range of (25 to $70^{\circ}C$), whose pre-compensated optical characteristic balances the spectral redshift and intensity decrease due to the temperature rising during operation.

• Proceedings of the Optical Society of Korea Conference
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• 1990.07a
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• pp.123-132
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• 1990

The method of characteristic matrix used in the calculation of multi-layered optical coating is applied to the analysis of DFB waveguide with arbitrary structure of grating by plecewise approximation where the DFB structure is devided into many sections in which the gain and period, amplitude and phase of DFB structure are assuced to be constant in each section. The DFB structure with two section is analyzed using this method of C-matrix. The possible applications for photonic devices using DFB waveguides are proposed.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.679-683
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• 2005

In this study, we investigate the characteristic of the poly-Si grain and morphology influenced by XeCl excimer laser system. The stable laser beam source is basic requested; the irradiation beam through optical lens module is more important which limit the grain size smaller than $0.5{\mu}m$. The homogenization lens designs control the poly-Si grain size; so we hardly get enlarge grain size by one laser irradiation scan.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.118-119
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.200-201
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• 2001

헬멧 장착형 HMD(Head-Mounted Display) 시스템은 비행기 조종사나 저격수의 시선을 크게 움직이지 않고 군사 전술상의 현재 상태를 볼 수 있도록 하여 눈의 피로감을 줄이고 시선의 이동에 의한 돌발적인 사고의 위험을 감소시킬 수 있어 군사적으로 유용한 장치이다 HOE(Holographic Optical Element)의 중요한 응용 분야 중 하나로 HMD에서의 결상 렌즈 또는 광 결합기가 있다 HMD 시스템에서 HOE의 역할은 2차원의 단색 디스플레이 영상을 헬멧 착용자의 눈에 반사하여 결상시키는 것이다. (중략)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.201-204
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• 1999

Polarization mode dispersion (PMD) restrict the bend-width of single mode optical filer, and it is important parameter in the optical fiber having long-length. Although fiber has perfect circular symmetry, fiber bending, twisting and laws governing manufacture cause additional Polarization mode dispersion. The effect of polarization mode dispersion in general single mode fiber of long length is discussed in this paper. Measurement of PMD with random mode coupling were conducted in two kind of fibers using different laws governing manufacture and interferometric method.

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.500-509
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• 2016

Integrating spheres play a central role in the radiometric calibration of remote sensors. With the development of the wide field of view (FOV) remote sensors, aperture diameters of remote sensors are becoming larger and larger. To satisfy the radiometric calibration requirements of full FOV and full aperture, an 8000mm diameter large aperture integrating sphere uniform source with a variable exit port was designed and manufactured. This integrating sphere will be used for pre-launch test and radiometric calibration of remote satellites. In this paper, optical theories were used to design the output spectral radiance. The LightTools software based on ray-tracing simulation method was used to determine the best combination and distribution of inner light sources. A spectral experiment was made to verify the spectral radiance design. To reduce the influence of longtime power-on, a new characteristic measurement method was developed to obtain the radiation characteristic of the integrating sphere, which could greatly improve the measuring efficiency. This method could also be applied to measure other large aperture uniform sources. The obtained results indicate that the spatial uniformity is 98.35%, and the angular uniformity at center position is 98.78%.

• Current Optics and Photonics
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• v.5 no.2
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• pp.141-146
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• 2021

We have evaluated the suppression effect of atmospheric-turbulence-induced optical scintillation in terrestrial free-space optical (FSO) communication systems using a gain-saturated erbium-doped fiber amplifier (EDFA). The variation of EDFA output signal power has been measured with different amounts of gain saturation and modulation indices of the optical input signal. From the measured results, we have found that the peak-to-peak power variation was decreased drastically below 2 kHz of modulation frequency, in both 3-dB and 6-dB gain compression cases. Then, the power spectral density (PSD) of optical scintillation has been calculated with Butterworth-type transfer function. In the calculation, different levels of atmospheric-turbulence-induced optical scintillation have been taken into account with different values of the Butterworth cut-off frequency. Finally, the suppression effect of optical scintillation has been estimated with the measured frequency response of the EDFA and the calculated PSD of the optical scintillation. From our estimated results, the atmospheric-turbulence-induced optical scintillation could be suppressed efficiently, as long as the EDFA were operated in a deeply gain-saturated region.