• 한국통신학회논문지
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• 제27권7C호
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• pp.712-722
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• 2002

광코드분할 다중접속을 위한 새로운 광복호기를 연구했다. 기존의 광부호기와 복호기는 단순하다는 장점은 가지나 복호화 과정에서 발생되는 sidelobe 세기에 의해 접속할 수 있는 사용자 수가 제한된다. 따라서 기존의 연구에서는 sidelobe와 상호상관 신호들의 중첩을 최소화시키는 코드를 만들어 시스템 성능을 개선시키려고 했다. 그러나 지금까지는 획기적인 새로운 방법론이 제시되지 못하고 있는 실정이다. 그러므로 sidelobe나 상호상관 세기를 최소화하거나 소거시킬 수 있는 새로운 광부호기 또는 복호기 연구의 필요성이 요구되고 있다. 본 논문에서는 1$\times$2 또는 1$\times$3커플러와 광 thyristor를 이용한 AND게이트 논리소자(AGLE)를 설계하였고, K(가중치)개의 AGLE로 구성된 새로운 광복호기를 창출하였다. 광 thyristor의 동작원리는 중첩된 광신호만 통과시키고, 중첩되지 않은 펄스들은 소거시킨다. 이러한 개념은 hard-limiter와 같은 동작을 행하는 것이다. 그러므로 이러한 구조를 가진 새로운 광복호기를 시스템에 적용하여 모의실험을 통해 결과를 분석하였다. 사용자 두 명에 대해, 기존의 제시된 결과에서 나타나는 sidelobe와 상호상관 세기가 완전히 소거시킬 수 있음을 보였다.

• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.52-59
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• 1997

In this paper, we propose a system design for a parallel3-dimensional optical interconnection network utilizing variable grating mode liquid crystal devices (VGM LCD's) which are optical transducers capable of performing intensity-to-spatial-frequency conversion. The proposed system performs real-time, reconfigurable, but blocking and nonbroadcasting 3-dimensional optical interconnections. The operating principles of the 3-D optical interconnection network are described, and some of the fundamental limitations are addressed. The system presented in this paper can be directly used as a configuration of switching elements for the 2-D optical perfect-shuffle dynamic interconnection network, as well as for a B-ISDN photonic switching system.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.477-484
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• 2014

In this paper, we propose a new optical secret key sharing method based on the Diffie-Hellman key exchange protocol required in cipher system. The proposed method is optically implemented by using a free-space interconnected optical logic gate technique in order to process XOR logic operations in parallel. Also, we present a compact type of optical module which can perform the modified Diffie-Hellman key exchange for a cryptographic system. Schematically, the proposed optical configuration has an advantage of producing an open public key and a shared secret key simultaneously. Another advantage is that our proposed key exchange system uses a similarity to double key encryption techniques to enhance security strength. This can provide a higher security cryptosystem than the conventional Diffie-Hellman key exchange protocol due to the complexity of the shared secret key. Results of numerical simulation are presented to verify the proposed method and show the effectiveness in the modified Diffie-Hellman key exchange system.

• 한국정밀공학회지
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• 제21권4호
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• pp.194-201
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• 2004

Optical fibers are indispensable fer optical communication systems that transmit large volumes of data at high speed. But the aligning technology under the sub-micron accuracy is required for the precise axis adjustment and connection. For the purpose of precise alignment of the optical arrays, in this research, we have developed the 12-axis(with 8 automated axis and 4 manual axis) automatic optical fiber alignment system including the image processing-based searching system, the automatic loading system using the robot and the suction toot and the automatic UV bonding system. In order to obtain the sub-micron alignment accuracy, two 4-axis PC-based motion controllers and the two 50nm resolution 6-aixs micro-stage actuated by micro stepping motors are adopted. The fiber aligning procedure consists of two steps. Firstly, the optical wave guide and an input optical array are aligned by the 6-axis input micro-stage with the IR camera. The image processing technique is introduced to reduce primary manual aligning time and result in achieving the 50% decrease of aligning time. Secondly, the IR camera is replaced by the output micro-stage and a wave guide and two optical arrays are aligned simultaneously before the laser power intensity delivered to the optical powermeter reached the threshold value. When the aligning procedure is finished, the wave guide and arrays are W bonded. The automatic loading/unloading system is also introduced and the entire wave guide handing time is reduced significantly compared to the former commercial aligning system.

• Current Optics and Photonics
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• 제2권5호
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• pp.395-399
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• 2018

This article investigates the mechanism of electronic signal phase noise degradation induced by laser phase noise in optical links comprising optical resonators. Through theoretical derivation, we find that the phase noise of the output electronic signal has the same spectral shape of optical intensity noise as the output of the optical resonator. We propose that the optical resonator transfers laser phase noise to light intensity fluctuation and then the intensity fluctuation is converted to electric phase noise through AM-PM conversion mechanism in the photodiode. An optical link comprising a Fabry-Perot resonator was constructed to verify the proposed mechanism. The experimental results agree with our theoretical prediction verifying that the supposition is correct.

• 한국광학회지
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• 제34권4호
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• pp.157-169
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• 2023

헤드 마운티드 디스플레이(head mounted display, HMD)를 이용한 증강 현실(augmented reality, AR)은 군사, 의료, 제조, 게임 및 교육 등 다양한 분야에서 활용되고 있다. 본 논문에서는 HMD에 가장 필수적인 AR 광학계의 설계 및 제작에 대해 논의한다. HMD용 AR 광학계는 디스플레이의 증강 영상과 현실 세계를 동시에 볼 수 있는 넓은 투명 영역이 필요하다. 이를 위해, AR 광학계를 각각의 특성에 따라 세 부분으로 나누어 설계 및 제작하였다. 그리고 3개의 광학계를 하나의 완전한 AR 광학계로 만들기 위해 필요한 ultra-violet (UV) 접착층의 굴절률을 고려해 설계함으로써 입력 광원이 UV 접착 층을 통과할 때의 광경로 이동(shift) 현상을 최소화하였다. 또한, AR 광학계를 설계할 때 축외 수차를 보정하고 양산에 적합하도록 2개의 비구면을 사용했다. 끝으로 HMD 양산을 위해 두께 11 mm, 대각선 화각(diagonal field of view) 40°, 무게 11.3 g의 비구면 AR 광학계를 설계하고 제작하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.488-491
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• 2003

Biochip-based diagnostic technology is an effective, time- and money- saving way. But, biochip analyzer including CCD imaging system has a complete optical system. It is one of reasons that the cost of biochip analyzer is expensive with CCD imaging system. In this paper, We suggested the simple and effective optical system for biochip analyzer with CCD imaging system. It consists of two parts with the same structure but opposite direction. Each part consists of achromatic doublet and meniscus. Suggested optical system has less lenses than existing system and more efficiently.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.75-79
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• 2009

A four beam interference optical system for laser micro structuring using a pulse laser was demonstrated. The four beam interference optical system using a pulse laser(picosecond laser) can fabricate micro structure on mold material(NAK80) directly. Micro structure on the polymer can be reproduced economically by injection molding of the micro structure on the mold material. The four beam interference optical system was composed by the DOE(Diffractive Optical Element) and two lenses. The laser intensity distribution of four beam interference was explained by an interference optics point of view and by the image optics point of view. We revealed that both views showed the same result. The laser power distribution of a $1{\mu}m$ peak pattern was made by the four beam interference optical system and measured by the objective lens and CCD. A $1{\mu}m$ pitch dot pattern on the mold material was fabricated and measured by SEM(Scanning Electron Microscopy).

• Current Optics and Photonics
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• 제4권4호
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• pp.310-316
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• 2020

We propose and experimentally demonstrate an all-optical radio frequency (RF) spectrum broadening system based on time compression. By utilizing the procedure of dispersion compensation values, the frequency domain is broadened by compressing the linear chirp optical pulse which has been multiplexed by the radio frequency. A detailed mathematical description elucidates that the time compression is a very preferred scheme for spectrum broadening. We also report experimental results to prove this method, magnification factor at 2.7, 8 and 11 have been tested with different dispersion values of fiber, the experimental results agree well with the theoretical results. The proposed system is flexible and the magnification factor is determined by the dispersion values, the proposed scheme is a linear system. In addition, the influence of key parameters, for instance optical bandwidth and the sideband suppression ratio (SSR), are discussed. Magnification factor 11 of the proposed system is demonstrated.

• 한국광학회지
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• 제32권1호
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• pp.15-21
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• 2021

본 논문에서는 LED 광원 모듈과 시준용 프레넬 렌즈를 이용하여 항공기 장애등 광학 시스템을 설계하였다. 설계된 광학계는 국토 교통부 항공기 경고등의 수직 양각 중심 광도 20,000 cd와 발산각 광도 규격 조건을 만족시키기 위해 프레넬 렌즈를 모듈별로 설계하였다. 또한 LED 광원 모듈과 프레넬 렌즈의 위치와 기울기를 조정하여 광학 시스템을 최적화하였으며, 이렇게 설계된 광학계의 배광 특성을 분석하고 비교하여 최적의 성능을 가진 항공기 경고등 광학계를 설계하였다.