• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.177-180
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• 1991

본 연구는 광 패턴 인식을 위한 사진 위상 필터(QPOG)를 분석하였다. 사진 위상 필터를 이용하여 광 패턴 인식을 한 경우 특정한 패턴에 대해서는 판별력이 뛰어나지만 한 패턴이 다른 패턴의 부분 패턴이 되면 판별력이 떨어짐을 알 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.105-111
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• 2000

To realize a desired characteristics of an optical transversal fitters, The number of optical amplifiers as same as the lentgh of a given transfer function is needed In this paper, we consider an optical transversal filter that uses only one fiber amplifier, which can realize a constant(=$\alpha$) times of a given transfer function with e as large as possible in order to make use of optical signal energy. We also present some applications using this optical fiber filter.

• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.190-195
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• 2007

A novel optical coupling filter with finite-thickness metal-strip gratings printed on optical planar dielectric slabs is proposed, and Bragg conditions of the device are rigorously evaluated by using Modal Transmission-Line Theory (MTLT). The numerical results reveal that the guiding structures have filtering properties due to a leaky-wave stop-band while conventional DFB guiding structures consisted of dielectric gratings depend on a feedback-wave stop-band. Consequently, it shows that the optical coupling titter dependent on the leaky-wave filtering characteristics can be compounded of such optical devices as LD and optical fiber.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.259-261
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• 2007

본 논문에서는 DWDM용 광필터를 설계하기 위하여 광섬유 다층 슬래브 도파로에 결합시킨 형태의 광섬유/다층 슬래브 결합구조의 광필터를 제안하였다. 광섬유와 슬래브의 분리간격이 $3{\mu}m$일 때 제안된 광필터는 $1.3{\mu}m$의 통신창에서 편광 독립성은 32nm로서 TM 모드와 TE 모드에 대해 중심파장이 각각 $\lambda_0=1.274755{\mu}m$와 $\lambda_0=1.30591{\mu}m$일 때 0.1 nm의 FWHM(Full Width at Half Maximun) 특성을 가진다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.03a
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• pp.305-311
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• 1998

본 논문에서는 회전과 크리에 무관한 상관결과를 얻기 위하여 WCHF-fSDF(wavelet circular harmonic function-filter modulation synthetic discriminant function)필터를 제안하였다. WCHF-fSDF 필터는 기준영상에 대하여 크기변화된 영상들을 웨이브릿 변환한 후, 이들로부터 추출한 단일 원형고조함수를 학습영상으로 사용하여 합성한다. 웨이브릿 변환은 입력영상과 웨이브릿 함수와의 상관으로 정의되므로 웨이브릿 변환을 이용한 패턴인식을 하기 위해서는 두 개의 4f 광 상관 시스템이 필요하다. 여기서 입력영상에 필요한 웨이브릿 함수를 제안된 필터의 설계과정에 포함시켜 전체 광 상관 시스템을 하나의 4f 광상관시스템을 대체시켰다.

• 연구논문집
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• s.33
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• pp.111-122
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• 2003

The automatic assembly system of micro optical filter is a key technology in the development of optical modules with high functionality. In order to create such automatic assembly system of optical filter, we have developed the system and program capable of evaluation of $30\mum$-thick film optical filter as well as conventional optical filters performances. Moreover, we have carried out the evaluation of optical filter using developed system and program, and we have compared and analyzed them with by conventional hand work. As results, the measured performances based on the present system are more fast, precise and reliable then those of the conventional hand work. In addition to that, the system can apply for various optical collimators and filters.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.152-153
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• 2001

파장 가변형 광 필터와 파장 선택형 광 스위치는 파장분할다중 광통신 및 광 교환 시스템을 구현하는데 매우 중요한 소자들 중의 하나이다. 특히 음향광학효과를 이용한 파장 가변형 광 필터(AOTF ： Acousto-Optic Tunable Filter)는 150nm 이상의 넓은 파장 가변범위, 1.5nm이하의 좁은 통과대역폭, 수 $\mu\textrm{s}$ 정도의 비교적 빠른 스위칭 속도 그리고 여러 개의 파장 채널을 동시에 선택할 수 있는 장점들을 가지고 있지만, 한편으로 표면 음향파(SAW： Surface Acoustic Wave) 구동에 필요한 RF 파워와 부 모드 (sidelobe)가 비교적 크다는 단점 때문에 실용화에 많은 제약을 받아왔다. (중략)

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.189-195
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• 2003

The objective of this study is to improve the optical sensitivity of laser fluorescence for detection of incipient enamel caries. An incipient carious lesion was formed in various stages by placing an enamel specimen of a bovine tooth in STPP demineralization solution. After measuring the optical density of the lesion surface by laser fluorescence induced by argon laser and various alter of yellow(500-520nm), amber(520-540nm), orange(540-560nm), and red(560-580nm), the specimen was cut vertically to measure the depth of the lesion using a polarizing microscope. SAS statistical program was used to analyze the relationship between the optical density of the lesion suface and the depth of the lesion. The results were as follows: 1. The optical density of early carious lesion, measured by laser fluorescence with amber and orange filter, and lesion depth observed by polarizing microscope, were increased as demineralization time increased. 2. The correlation coefficient between optical density of the lesion surface and the histological depth of the lesion was the highest in orange filter(r=0.49), followed by amber(r=0.32), yellow(r=0.13) and red(0.01). 3. Regression analysis showed that the most linear relationship between the optical density and the lesion depth was existed in orange filter group. In regard above results, laser fluorescence could be considered to be reliable for optical diagnosis of dental caries.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.419-423
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• 1999

Optical filters utilizing the evanescent filed coupling between the side polished fiber and polymer planar waveguide were fabricated and optical properties of the devices were measured. A scheme for reducing polarization dependent properties of the device was proposed and demonstrated experimentally. Our measurement results showed that resonance wavelengths and filtering depth of the optical filters can be determined by adjusting thickness of planar waveguide and polishing depth of the fiber. The device fabrication procedure including fiber polishing steps and formation of polymer planar waveguide were described. The optical characteristics of fabricated optical filers were that 3 dB bandwidth was 15 nm, the resonance wavelength difference between the TE and TM polarized response was less then 2 nm, and insertion loss was less then 0.2 dB. The measured resonance wavelength drift dut to the variation of ambient temperature was -0.35 nm/$^{\circ}C$.

• Korean Journal of Optics and Photonics
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• v.25 no.2
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• pp.61-66
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• 2014

We report the characterization of a wavelength-swept laser (WSL) using a polygon-based wavelength scanning filter and two semiconductor optical amplifiers (SOAs). The output intensity and scanning bandwidth of the WSL depend on the position of the two SOAs in the laser cavity and the coupling ratio of the output fiber coupler. The outputs of the WSL are characterized for coupling ratios of 10%, 30%, 50%, 70%, and 90% for the output fiber coupler. In the setup in which the output fiber coupler is located between the two SOAs, high output power and wide scanning bandwidth can be achieved with an optimized configuration. Using the optimized configuration of the WSL, the intensity increases with the coupling ratio. These results can be used to construct an optimized WSL using the polygon-based wavelength scanning filter.