• The Journal of the Acoustical Society of Korea
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• v.2 no.1
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• pp.20-26
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• 1983

본 논문에서는 단일모드 광섬유의 intrinsic birefringence 와 파라데이회전에 대한 이론적 해석을 하였다. 분석과정에서 단일모드 광섬유는 선형지연기로 모델링하였으며 측정결과 intrinsic birefringence 는 약 1.4rad/m로 나타났다. 그리고 자계의 영향에 의한 빛의 편광상태 변화에 대한 이론적 해석을 하 였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.101.2-101.2
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• 2016

육각형 구조의 탄소원자가 이차원으로 배열된 그래핀은 고유의 전기적, 광학적 특성으로 인하여 새로운 전기소자, 광학소자 및 광전소자를 구성하는 유망한 물질로써 많은 주목을 받고 있다. 특히 넓은 파장 대역에서의 일정한 광 흡수 특성, 높은 비선형 광학 계수 및 수백 펨토초의 매우 빠른 비선형 응답시간으로 인하여 최근 그래핀을 기반으로 하는 광대역 광 편광소자, 비선형 광 신호 발생기, 광 포화 흡수체 및 광 제한기 (optical limiter) 등이 보고되고 있다. 본 발표에서는 그래핀 등 저차원 물질의 비선형 포토닉스 응용에 관한 최근 연구에 관하여 살펴보고자 한다. 특히 그래핀 소자의 전기적 조절을 통한 극초단 레이저 펄스의 발생 및 제어 특성을 살펴보고 나아가 높은 효율을 가지는 도파로 기반 그래핀 광전소자 구현 가능성 및 그 한계에 관해 살펴보고자 한다.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.25-30
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• 1994

We derive a set of formuale which show one-to-one correspondence between the the unitary Jones matrices of transparent anisotropic media and the rotational transformations on the Poincare sphere. By using the formuale one can determine the vectorial representation of the rotational transformation on the Poincare sphere which specifies the direction of the axis and the angle of the rotation in terms of the three parameters specific to the corresponding unitary Jones matrix, and conversely the the three parameters of the uniatry Jones matrix in terms of the vectorial representation of the corresponding rotational transformation on the Poincare sphere. To understand the polarization transmission characteristics of an optical system consisting of transparent linear anisotropic media, start with the Jones calculus to get the unitary Jones matrix for the whole system and then convert it to a rotational transformation on the Poincare sphere, from which we can intuitively understand the effect of the optical system on the polarization state of the light passing through the system.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.405-405
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• 2012

InSb는 높은 전자이동도와 낮은 밴드갭을 가지고 있어 저전력 고효율의 고주파소자 및 비선형 광소자에 적합한 물질이다. 특히 InSb 기반 소자들은 전자-포논효과의 영향을 덜 받는 저온에서 고감도 소자로도 사용되고 있는데, 소자의 최적합 설계와 제작시의 실시간 성장제어를 위해서는 넓은 온도범위에서의 InSb의 광물성이 필요하다. 분광타원편광분석법(ellipsometry)은 물질의 광특성인 유전율 함수를 정확하게 측정 할 수 있은 기술로써, InSb 에 대한 유전율 함수는 많은 연구를 통해 잘 알려져 있다. 그러나, 온도변화에 대한 연구로는 100-700 K, 1.2-5.6 eV의 제한된 온도와 분광영역에서만 이루어졌다. 본 연구에서는 보다 확장된 온도범위(25-686 K), 광역 에너지 범위 (0.74-6.5 eV)에서 분광타원편광분석 연구를 수행하였다. 그 결과 저온에서의 전자-포논 효과의 감소로 인한 청색천이와 보다 명확한 전자전이점들의 값을 얻었다. 특히, 100 K 까지의 이전 연구에서는 구분할 수 없었던 $E_2'$ 전이점을 본 연구의 25 K 의 유전율 함수에서 명확히 구분할 수 있었고, 고에너지 영역의 $E_1'+{\Delta}_1+{\Delta}_1'$ 전이점의 온도의존성을 처음으로 연구하였다. 본 연구의 결과는 InSb 를 기반으로 한 광전자 소자의 개발 및 적용분야와 밴드갭 엔지니어링 분야에 많은 도움이 될 것으로 예상한다.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.38-43
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• 2004

This paper describes the construction of a circular polariscope. Generally, a circular polariscope contains four optical elements and a light source. The first element following the light source is called the linear polarizer. It converts the ordinary light into plane-polarized light. The second element is a quarter wave plate which converts the plane-polarized light into circularly polarized light. Following the quarter wave plate, a specimen made of transparent photoelastic material is located in a loading device. The second quarter wave plate is set and the last element is the analyzer. These polarizing elements, two quarter wave plates and two linear polarizing filters, were purchased from the USA. Frames and other structures for holding polarizing filters were machined and assembled to be rotated. Light box, which includes four incandescent lamps and two sodium-vapor lamps, was made. In order to proof the function of the newly built polariscope, Tardy compensation test was applied to a rectangular shaped specimen made of poly-carbonate material (PSM 1). The error of the fringe constant, which was measured by the newly built polariscope, was within 4.4 percent compared to the standard value of this material. It is possible to make a good quality of polariscope if accurate polarizing filters will be used.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.135-141
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• 2004

We developed a polarimetric fiber-optic current sensor system for protective relaying usage. A fiber sensing coil that consisted of a length of twisted fiber and a FRM (Faraday rotator mirror) was used in order to suppress the linear birefringence effect. From the experiments with various sensing coil configurations and environmental conditions, the proposed current sensor system showed feasibility of suppressing environmental noises, and the obtained measurement stability was less than $\pm$3％ at rated primary current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.6
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• pp.533-537
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• 2000

It was known that chalcogenide glasses have the superior property of the photoinduced anisotropy(PA). In this study we observed the phenomenon of Ag polarized-photodoping in chalcogenide As$_{40}$ /Ge$_{10}$/Se$_{15}$ /S$_{35}$ and the double-layer of Ag doped As$_{40}$ /Ge$_{10}$/Se$_{15}$ /S$_{35}$ thin film using the irradiation with the polarized He-Ne laser light. The Ag polarized-photodoping results in reducing the time of saturation anisotorpy and increasing the sensitivity of linearly anisotropy intensity up to maximum 220% The Ag polrized-photodoping shows improvement of the photoinduced anisotropy property in polarized photodoping of the chalcogenide thin film. It will offer lots of information for the photodoping mechanism and analysis of chalcogenide thin film.in film.ilm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.574-577
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• 1999

The chalcogenide glasses of thin films have superior property of the photoinduced anisotrophy(PA). In this study, we observed the phenomenon of Ag polarized photodoping using the irradiation with polarized He-Ne laser light, in the thin film of chalcogenide As/sub 40//Ge/sub 10//Se/sub 15//S/sub 35/ and the double-layer of Ag doped As/sub 40//Ge/sub 10//Se/sub 15//S/sub 35/. The Ag polarized photodoping result in reducing time of saturation anisotrophy and increasing sensitivity of linearly anisotrophy intensity, up to maximum 220%. In the thin films of chalcogenide, the Ag polarized photodoping will be show a capability of new method that suggested more improvement of photoinduced anisotrophy property

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.419-427
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• 1996

Thermally-stabilized fiber-optic current sensors are proposed and demonstrated. The sensor head is made of two coil formers combined perpendicularly. In this sensor head, bending-induced birefringences can be reduced to the level much smaller than those of the single former type because the eigen-axes of the two perpendicular coil formers are made orthogonal to each other. Moreover, thermal variation of the birefringence is also expected to be minimized by the orthogonality of the two polarization eigen-axes. We changed the temperature slowly in the range of 20~45$^{\circ}C$ during 100 minutes. The overall linearity of the sensor is better than 1.2% in the range of 0~1000A. The long-term fluctuation of the sensor is less than 1% when measured for 3 hours at 500A and room temperature. Two orthogonally-polarized laser diodes are combined together to make the incident beam unpolarized. In the signal processing, the signals are separated by two parts and normalized respectively, which minimize the efects of optical fluctuations coming from sources, connectors, etc.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.3
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• pp.179-187
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• 2008

In this paper, we carried out the performance evaluation of depolarized fiber optic gyroscope(D-FOG) that was designed and fabricated with the low-cost optical communication single mode fiber and depolarizer. In order to reduce the phase error of D-FOG, the circuit of stabilized current and temperature of the light source was made and the performance was analyzed. The current and the temperature stability of the fabricated stabilization circuit were less than $200{\mu}A$ and $0.0098^{\circ}C$, respectively. Also, the D-FOG's experimental result showed that the value of the dynamic range of rotated rate, the scale factor error with a good linearity, and the zero bias drift were ${\pm}50^{\circ}/s$, 2.8881%, and $19.49^{\circ}/h$, respectively. The results indicated that a low-cost FOG was able to fabricate which was more cost effective than conventional FOG with a high-cost high-birefringent polarization maintaining fiber.