• 한국정보통신학회논문지
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• 제25권3호
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• pp.478-485
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• 2021

광 주입 잠금 반도체 레이저의 주입 매개 변수를 조절하여 광학적 복소 신호를 생성 할 수 있다. 그러므로 정확한 주입 매개 변수의 결정은 광학적 복소 신호 생성 기술에서의 핵심 요소이다. 기존의 주입 매개 변수의 추출 이론은 광 주입 잠금 반도체 레이저의 비율 방정식을 사용하며, 이는 locking map 기반의 보간법을 사용하기 때문에 정확한 주입 매개 변수의 추출에 한계가 있다. 이를 해결하기 위하여 비율 방정식의 새로운 해석법을 제안한다. 제안된 해석법은 비율 방정식을 광학적 복소 신호의 생성에 맞게 수정하여 주입 매개 변수를 직접적으로 도출하는 방법이며, 이를 통하여 보간법을 통한 복소 신호 생성 대비 103 배의 오차 감소를 달성하였다.

• 천문학회보
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• 제36권2호
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• pp.153.1-153.1
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• 2011

For the stars cooler than the Sun, it is difficult to determine the stellar parameters and chemical abundances because of the strong molecular lines in the optical region. Therefore the NIR high-resolution spectra, such as those obtained by IGRINS would be a solution to determine the stellar parameters for late-type stars, such as M dwarfs. As using the NIR high-resolution spectra, we are expecting that it would be more reliable to compare observed spectra with synthetic spectra for the stellar parameters. In order to confirm the method by using high-resolution spectra in NIR band, it should be cross-checked against the stellar parameters from optical high-resolution spectra. We have derived the stellar parameters of M dwarfs using the synthetic spectra in the long wavelength region of the optical spectra (over 8000 $\bar{A}$), which is relatively less contaminated by molecular lines as well as telluric lines.

• Journal of Astronomy and Space Sciences
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• 제16권2호
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• pp.273-284
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• 1999

위성용 star tracker의 국내 개발을 위한 기초 연구의 일환으로 광학계 설계 요소 선정 과정을 연구하였다. 논리적인 광학 요소 선정을 위해 CCD 센서에 결상된 별빛을 관련 전자회로에서 읽고, 처리하는 전 과정을 시뮬레이션하였다. 시뮬레이션으로부터 별의 등급과 성취 가능한 지향 정밀도간의 관계가 구해졌으며, 그 관계로부터 요구되는 star tracker의 지향 정밀도를 만족시키기 위한 최적의 광학요소를 유도하였다. 선정된 광학 요소들은 10 arcsec의 지향 정밀도를 갖는 star tracker의 광학계 설계에 사용되었다.

• 천문학회보
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• 제36권2호
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• pp.151.2-151.2
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• 2011

IGRINS (Immersion GRating INfrared Spectrometer) will provide the spectra with high-resolution and an instantaneous spectral coverage of H and K band in NIR region. Therefore, it is expected that the wide coverage of wavelength would make a production of an extensive NIR high-resolution spectra of standard stars as a prior program of IGRINS. As a counter part of these NIR spectra, we have planned to obtain the high-resolution spectra of those standard stars in optical band. These optical high-resolution spectra would give us an opportunity to produce the library of high-resolution stellar spectra covering from optical to NIR band, and to confirm the method to determine the stellar parameters and chemical abundances from the NIR high-resolution spectra. Before using the NIR high-resolution spectra, we have tested the method to determine the stellar parameters by comparing between the observed spectra and the synthetic spectra in optical band. In order to make the synthetic spectra, we have used the Kurucz ATLAS9 model grids and the SYNTH code described by Fiorella Castelli (http://wwwuser.oat.ts.astro.it/castelli/). For the cross-check against the parameters that would be derived from the NIR spectra, the stellar parameters such as effective temperature and surface gravity were determined using the optical spectra of the solar-like stars, as preliminary results.

• 한국정밀공학회지
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• 제18권1호
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• pp.82-88
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• 2001

The demands of high data transfer rate and high recording density in optical disk memory device are being increased. In this paper, 4 design parameters for next generation optical disk are investigated. As for the high data transfer rate, two design parameters such as driving acceleration and transmissibility are introduced. As the high recording density is concerned, the minimum linearity and the tilt of the actuator are introduced. Two kinds of pickup actuator are used to evaluate the validity of the parameters through the simulation and the experiment. The 4-wire actuator has good linearity but bad stability and tilt characteristics, while the rotary and axis actuator has good stability for the external vibration but bad linearity. It is demonstrated that the newly proposed design parameters are available to design and evaluate quantitatively the performance of the actuator for the next generation optical disk.

• Journal of the Optical Society of Korea
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• 제8권3호
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• pp.99-103
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• 2004

This paper describes the optimal design of an AWG spectrum to meet various specifications and improve some physical parameters. The objective function is the norm of the difference between design parameters and target values. To obtain the design parameters, the Fourier model is employed and the design variables arc spacing of array waveguide, width of array waveguide, optical path difference, and focal length. The (1+1) Evolution Strategy is employed as the optimization tool. The optimization procedure is applied to a 16-channel AWG and the optimized design variables will considerably improve the system performance.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.470-475
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• 2016

In this paper, the effects of filter parameters on a supercontinuum-based all-optical thresholder are experimentally investigated. By tuning the filter parameters, the power transfer function and power transmission function are tailored. The experimental results show that a thresholder with short center wavelength has a better power function, and the slope in the middle level of the thresholder increases with increasing bandwidth. Through tuning the filter parameters, the thresholder can achieve a steplike power transfer function for optical thresholding, and a steplike power transmission function for optical self-switching. This makes the supercontinuum-based thresholder more flexible, and allows customization of performance to meet different demands in various applications.

• 대한기계학회논문집A
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• 제33권3호
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• pp.196-200
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• 2009

Lithium niobate ($LN:LiNbO_3$) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN devices, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult b traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters such as down force and relative velocity, were investigated for the LN CMP process To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance.

• Journal of information and communication convergence engineering
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• 제5권3호
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• pp.273-280
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• 2007

The numerical methods for finding the optimal parameters in 640 Gbps (16 channels $\times$ 40 Gbps) WDM system with optical phase conjugator (OPC) are proposed, which effectively compensate the distorted overall WDM channels. The considered optimal parameters are the OPC position and the dispersion coefficient of fibers. The numerical approaches are accomplished through two different procedures. One of these procedures is that the optimal OPC position is previously searched and then the optimal dispersion coefficient is searched at the obtained optimal OPC position. The other is the reverse of the above procedure. From the numerical results, it is confirmed that two optimal parameters depend on each other, but less related with the searching procedure. The methods proposed in this research will be expected to alternate with the method of making a symmetrical distribution of power and local dispersion in real optical link which is a serious problem of applying the OPC into multi-channels WDM system.

• 한국광학회지
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• 제33권1호
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• pp.35-44
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• 2022

광학계는 매우 다양한 용도로 사용되고 있기 때문에 유사한 구성의 광학계에서도 활용목적과 주어진 광학사양에 따라 다양한 설계가 존재한다. 하지만 광학수차는 광학계의 구조와 광학사양 모두에 영향을 받으므로 수차분석만으로는 광학설계의 고유한 특성을 파악하기 어렵다. 이 연구에서는 무차원의 설계변수를 사용하여 광학사양과 무관하게 광학설계의 수차특성을 파악하는 방법을 연구하고, 예시로서 서로 다른 용도와 사양을 가지는 4종의 triplet 설계를 분석하였다.