• 센서학회지
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• 제22권2호
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• pp.124-129
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• 2013

In this paper, we manufactured the regenerated FBG by the thermal annealing of seed FBG based on UV irradiation. The writing conditions of regenerated FBGs were investigated in four types of optical fiber. FBGs written in $H_2$-free fiber were erased and not regenerated during the thermal annealing. FBG written in $H_2$ loaded Boron co-doped fiber was erased at the temperature of about $580^{\circ}C$ and regenerated about $590^{\circ}C$. However, the extinction of regenerated FBG started at the temperature over $900^{\circ}C$ and then FBG disappeared out. FBG written in $H_2$ loaded Ge high doped fiber was erased and regenerated around the temperature of $800^{\circ}C$ and maintained until the end of the thermal annealing. The reflection of the regenerated FBG was decreased about 12 dB and the center wavelength of the regenerated FBG was shifted about 0.7 nm compared with that of the seed FBG. The thermal characteristics of the regenerated FBG were analyzed by reheating from room temperature to $980^{\circ}C$. As results, the regenerated FBG had survived without a decrease of reflection and the thermal sensitivity was $15pm^{\circ}C$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.978-982
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• 2004

We present high aspect ratio 100nm-scale nickel stamper using e-beam lithography process and Cr/Qz mask for the injection molding process of nano grating patterns. Conventional photolithography blank mask (CrON/Cr/Qz) consists of quartz substrate, Cr layer of UV protection and CrON of anti-reflection layer. We have used Cr/Qz blank mask without anti-reflection layer of CrON which is non-conductive material and ebeam lithography process in order to simplify the nickel electroplating process. In nickel electroplating process, we have used Cr layer of UV protection as seed layer of nickel electroplating. Fabrication conditions of photolithography mask using e-beam lithography are optimized with respect to CrON/Cr/Qz blank mask. In this paper, we have optimized e-beam lithography process using Cr/Qz blank mask and fabricated nickel stamper using Cr seed layer. CrON/Cr/Qz blank mask and Cr/Qz blank mask require optimal e-beam dosage of $10.0{\mu}C/cm^2$ and $8.5{\mu}C/cm^2$, respectively. Finally, we have fabricated $116nm{\pm}6nm-width$ and $240nm{\pm}20nm-height$ nickel grating stamper for the injection molding pattern.

• 한국광학회지
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• 제12권5호
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• pp.401-405
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• 2001

본 논문에서는 반사대역 내부에 분리된 다수의 통과대역을 갖는 영역이 분리된 첩 광섬유 격자를 이용하여 각 채널을 독립적으로 제어할 수 있는 광 툭과 필터를 제안하였다. 영역이 분리된 첩 광섬유 격자는 원하는 영역을 설정할 수 있는 슬릿을 사용하여 제작되었다. 분리된 대역은 압전소자에 광섬유 신장기를 부착하여 조절하였고, 조절된 반사 대역은 채널을 독립적으로 선택하는데 사용되었다. 광대역 광원과 파장가변 레이저를 사용하여 투과 스펙트럼의 파장이동에 따른 입력 채널의 선택을 보였다.

• 마이크로전자및패키징학회지
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• 제22권3호
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• pp.73-77
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• 2015

본 논문에서는 저가로 쉽게 제작할 수 있는 구조를 지닌 단일칩 형태의 고분자 기반 평판형 분광모듈을 제안하였다. 제안된 분광모듈은 UV 임프린트 기법에 의해 제작되어진 비등간격 나노회절격자와 오목거울이 포함된 평판형 광도파로로 구성되어진다. 회절효율을 향상시키기 위해 나노회절격자의 구조는 $25^{\circ}$의 블레이징 각도와 100nm의 선폭을 가지도록 설계, 제작되었다. 평판형 분광모듈은 700 nm 대역폭과 10 nm 분해능을 가짐을 확인하였다. 이러한 집적형 고분자 분광모듈은 다양한 센서 시스템에 적용될 수 있을 것으로 기대된다.

• 한국광학회지
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• 제15권1호
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• pp.34-38
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• 2004

파장가변형 광섬유레이저로 광섬유격자 센서어레이를 복조하는 방법을 제안하였다. 레이저의 출력파장을 시간지연 샘플링으로 분석하고 이를 이용하여 기존 시스템의 비선형적 동작특성을 개선하였다. 계산된 파장값은 센서어레이 출력파평의 각 피크에 할당되어 파장가변필터의 비선형성에 영향받지 않고 가해진 물리량에 대하여 항상 선형적인 출력을 얻게 하였다. 실험을 통하여 약 20 pm의 분해능을 얻었으며 이는 고속의 위상변조를 사용할 경우 크게 개선될 수 있음을 보였다.

• 방송과미디어
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• 제6권2호
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• pp.84-101
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• 2001

In this paper, we present a primitive system design of a super multi-view(SMV) 3-D display system based on a focused light array(FLA) concept using reflective vibrating scanner array(ViSA). The parallel beam scanning using a vibrating scanner array is performed by moving left and right an array of curvature-compensated mirrors or diamond-ruled reflective grating attached to a vibrating membrane. The parallel laser beam scanner array can replace the polygon mirror scanner which has been used in the SMV 3-D display system based on the focused light array(FLA) concept proposed by Kajiki at TAO(Telecommunications) Advancement Organization). The proposed system has great advantages in the sense that it requires neither huge imaging optics nor mechanical scanning pals. Some mathematical analyses and fundamental limitations of the proposed system are presented. The proposed vibrating scanner array, after some modifications and refinements, may replace polygon mirror-based scanners in the near future.

• 전자공학회논문지A
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• 제33A권10호
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• pp.90-97
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• 1996

A numerical method for scattering of electromagnetic waves from a periodic strip grating over a grounded dielectric slab is considered for TE and TM polarization cases from the viewpoints of both reflection grating problem and leaky wave antenna problem. The analysis is based on a mode expansion method, floquet's theorem, and the method of moments. Numerical results involving some combinations of geometric parameters are presented in terms of complex propagation constant (kd-$\beta$d diagram), radiation pattern, and relative scattered powers of spectral modes. In particular, the relationship between complex propagatio constnat form the viewpoint of leaky wqve antenna problem and Off-bragg and bragg blazing phenomena from the viewpoint of reflecton graing problem is investigated.

• 대한기계학회논문집B
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• 제20권9호
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• pp.2933-2943
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• 1996

A grating composed of elliptical cylinders (GEC), specially designed, is applicable to control of radiation heat transfer from a heated surface, as reported in our previous work. In this study, an analysis of radiation heat transfer is performed for a physical model in which the GEC is placed in front of a heated black-base surface and the major axes of the elliptical cylinders are inclined as a certain angle from the normal to the row of elliptical cylinders. Numerical solutions are obtained. Variations of the direction and the radiative energy concentration with slant angle of the major axis are shown for some parameters. It is verified that the GEC is able to widely change the direction of radiation heat transfer from the heated surface.

• 한국광학회지
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• 제6권4호
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• pp.296-301
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• 1995

광섬유격자와 단방향성 광섬유 loop mirror를 이용하여 단일모드로 발진하는 erbium첨가 광섬유레이저를 구성하였다. 이득매질인 erbium첨가 광섬유를 단방향성 loop내에 둠으로써 레이저광이 이득매질내에서 진행파를 이루도록 하고 loop 밖에서 반사 선폭이 0.2nm인 광섬유격자로 파장선택적 귀환시켜 주는 방식으로 공진기를 구성하였다. 수동형 광섬유 링공진기 형태의 광스펙트럼 분석기를 별도로 구성하여 광섬유레이저의 모드 스펙트럼을 관찰한 결과, 외부 온도변화로 인한 분 단위의 모드 튐을 제외하고는 대부분의 시간에 안정적인 단일모드 및 단일편광 상태의 특성을 나타냄을 확인할 수 있었다.

• Current Optics and Photonics
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• 제6권1호
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• pp.44-50
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• 2022

An off-axis zone plate is able to focus on a single order while neglecting the zeroth order in a visible imaging system. This allows one to enhance the contrast quality in diffractive images, which is the major advantage of this type of zone plate. However, most previous reflection zone plates are used in focusing X-rays with a small grazing incident angle and are intricately designed with the use of a local grating period. In this study, we suggest the design of an off-axis elliptical zone plate (EZP) that is used to focus a monochromatic light beam with separation between the first and unfocused orders under a large grazing incident angle of 45°. An assumption using the total grating period, which depends on the average and constant grating period, is proposed to calculate the desired distance between the first and zeroth order and to simplify the construction of a novel model off-center EZP. Four diffractive optical elements (DOEs) with different parameters were subsequently fabricated by direct laser lithography and then verified using a performance evaluation system to compare the results from the assumption with the experimental results.