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본 논문은 반사방지막의 성능을 더 정확히 비교 및 분석하기 위하여 기존 방법과 달리 반사방지막에 수직입사가 아닌 입사각이 $8^{\circ}$ 에서 $60^{\circ}$ 까지 변화한다고 가정하고 단층 구조와 다층 구조의 반사방지막의 평균반사율을 계산하고 비교하였다. 입사파의 파장범위를 400 nm ~ 1200 nm 라고 가정하고, 분석에 사용된 반사방지막의 구조는 두께 180 nm인 1차 및 5차 함수의 굴절률 분포를 갖는 6층 구조와 균일한 굴절률 분포를 갖는 단층구조이다. 분석 결과로써 180 nm 단층구조의 경우 평균반사율이 19.6 % 이고, 같은 두께의 6층 구조의 1차 함수 굴절률 분포에서는 14.2 % 이고, 5차 함수 경우에는 11.6 %의 결과를 얻어 균일한 굴절률 분포의 단층구조 보다 5차 함수 굴절률 분포를 갖는 6층 구조의 경우 약 8%의 반사율 감소 효과를 보았다. 이러한 결과는 향후 광소자 및 광 필터에 적용되는 반사방지막 제작에 용용 될 수 있다고 판단된다. 【This paper compares and calculates more precisely the averaged reflectance of antireflection coating with different structure of single and 6 layer assuming the incident angle of light changing from $8^{\circ}$ to $60^{\circ}$ not like normal incidence as usual case. The reflectivity of AR coating of 6 layers with 180 nm thickness having index profile suggested as linear and quintic function and single layer with same thickness having even index are calculated and compared, when the wavelength of incident light ranges from 400 nm to 1200 nm. As the results the AR coating with 6 layers having quintic(linear) function index profile shows the lower reflectance about 11.6 %(14.6 %) than other index profiles, which is approximately 8 % lower reflectance compared with single layer case(about 19.6 %). This results could be applied for the better antireflection coating design applying to optical devices and filters.】

This paper shows an antireflection coating design skill for utilization the thin-film silicon solar cell in the future. The reflectivity of each index profile previously suggested as linear, cubic and quintic function has been calculated and compared. Each index profile is applied to the antireflection coating consisting of 6 layers with 180nm thickness. Also we suggest the graded index profile and compare it's reflectivity to the linear, cubic and quintic's ones. As a results we find the reflectivity generally decreases as the order goes to higher. However the reflectivity in the graded index profile shows the higher(lower) value than ones in the linear, cubic and quintic especially in the shorter(longer) wavelength range from 500 nm to below 700 nm(above 700 nm to 800 nm). Therefore we find that the graded index profile structure could be applied for the better antireflection coating design scheme especially for optical device and optical filter in the range of from deep red to infrared.

This paper is the research on the heated CWDM optical transmitter for the wavelength compensation at the low temperature. In general, the wavelength deviation of DFB laser is around 0.1 nm/C. The wavelength of DFB laser shifts to longer(shorter) wavelength according to the temperature increase(decrease). Typical CWDM optical communication network has 20 nm channel spacing from reference center wavelength per each channel. There is some limitation problem in the range of operating temperature due to the channel interference. For solving the limited temperature range problem, especially at the low temperature, we use the heater on the DFB laser. As a result, we could realize the CWDM optical transmitter to meet +/-6.5 nm from reference center wavelength in the range of temperature at , which is applicable to the industrial field.

본 논문은 박막 실리콘 태양전지에 적용되는 반사방지 또는 고반사 코팅 기술에 관한 연구이다. 태양광 흡수율을 개선하기 위하여 박막 실리콘 태양전지의 앞면에는 반사를 줄이는 반사방지막 기술이 필요하며, 뒷면에는 반대로 반사를 높이는 고반사 기술이 필요하다. 반사방지막 기술에서 단층의 구조에서는 코팅의 두께에 따라 반사율이 틀려지고, 적절한 범위에서 두께를 제어하면 낮은 반사율을 얻을 수 있다. 대칭형태의 다층의 구조에서는 단층구조에 비해서 넓은 파장대에 걸쳐서 낮은 반사율을 얻을 수 있다. 또한 뒷면에 적용되는 고반사막 기술에서는 높은 굴절율을 갖는 매질과 낮은 굴절율을 갖는 매질을 대칭 구조로 구성하여 계산한 결과 높은 반사율을 얻을 수 있다는 것을 확인하였다. 【This paper presents a reflection coating design scheme in the thin-film silicon solar cell. The antireflection(high reflection) coating skill is needed in the front(back) panel of the thin-film solar cell to improve an efficiency of light absorbing. In the single structure a reflectivity is changed according to the thickness of coating for antireflection scheme and its minimum value can be obtained by controlling thickness of coating. In the symmetric multi layer structure low reflectivity can be obtained in the wide wavelength range. And we also find that high reflectivity can be obtained through multi layer structure, which has alternate layers of high and low material, for high reflection scheme in the back panel.】

This study has developed an effective reuse and retrieval system that can easily register modeled standard parts using a simple GUI (graphic user interface) even though designers may not know the rules of registration for a complex database. Also, the automatic generation of the optimized parts list has been investigated. The system has been developed in the Windows XP environment using an Open API (application programming interface) and a commercial CAD/CAM/CAE solution. It consists mainly of three kinds of module, i.e., a standard part module, parts-list module, and retrieval-system module. The standard part module is helpful for designers to effectively reuse or modify standard parts after registering them using a GUI. The parts-list module generates a parts list using either standard and/or non-standard parts. The retrieval-system module allows the effective retrieval and classification of standard parts. The system was applied to standardize mold bases and mold parts. It was applied to Hyundai Heavy Industry, S. Korea, which resulted in the reduction of design errors and design time.

This paper is the research on SMSR yield improvement of the optical transceiver using modulated DFB laser. In general, the wavelength of DFB laser optical transceiver are 1310, 1490 and 1550 nm. Usually SMSR in modulated DFB is difficult to improve as low as 30 dB because of high slop efficiency trade off. In modulation condition, we studied SMSR improvement according to adjust bias current, extinction ratio and optical line terminal receiver sensitivity. As our test results, we can found a method how to improve SMSR for optical transceiver for long distance.

A novel all-optical gain-controlled (AOGC) bidirectional amplifier is proposed and demonstrated in a compact structure. The AOGC function using fiber Bragg grating (FBG) pairs controls both directional signals independently, and combinations of optical interleavers and isolators suppress Rayleigh backscattering (RB) noise. The amplifier achieves high and constant gain with a wide dynamic input signal range and low noise figure. The performance does not depend on the input signal conditions, whether static-state or transient signals, or whether there is symmetric or asymmetric data traffic on bidirectional transmission. Transmission comparison experiments between invariable symmetrical and random variable asymmetric bidirectional data traffic verify that the all-optical gain control and bidirectional amplification functions are successfully combined into this proposed amplifier.

A new and simple calibration technique that greatly enhances the measurement sensitivity of conventional fiber-optic reflectometry based on Fresnel reflection from the tip of a fiber is used for demonstrating the feasibility of measuring solute concentrations and index changes in fluids to very high precision. The amplitude of pulses originating from reflection from the fiber-fluid interface is compared in real-time with the amplitude of reference pulses from a fiber-air interface such that errors caused by pulse amplitude fluctuations and slightly varying detector responses are corrected. Using solutions of salt and water, it is demonstrated that the technique is capable of measuring index changes of about $1 {\times} 10^{-5}$ corresponding to a salt concentrations of 0.01 %.

Our amplifier using an all optical method and a fixed GFF achieved automatic gain flatness through all C-band without any NF degradation, and simultaneously a constant 25 dB gain, while input signals were varied between one channel and forty WDM channels.