• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.301-306
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• 2014

A porous silicon microcavity (PSMC) sensor has been made for vapors of solvent solutions, and a method has been developed in order to obtain simultaneous determination of two volatile substances with different concentrations. In our work, the temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for ethanol and acetone solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations.

• Journal of Photoscience
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• v.9 no.2
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• pp.264-266
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• 2002

The absorption wavelength of the protonated retinal Schiff base can be controlled by the surrounding environment. An external anion is related to fine adjustment of the absorption wavelength. The addition of anion to retinochrome solution caused blue shift in spectra. The increase of the shift was dependent on the ion concentration. The large shift value was obtained as 20 nm at the saturated concentration of nitrate. The shift intensity for the nitrate addition exceeded that of chloride. Seemingly, it depends on the ionic strength or lyotropic character of the anion. However, neither of sulphate nor gluconate ion showed remarkable blue shift. These phenomena were accounted for with (1) delocalization of the positive charge in the conjugated polyene system, (2) ionic bonding strength between the counter ion (glutamate) and the proton, and/or (3) interaction of the added anion with the proton on Schiff base.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.6-11
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• 2004

The playback wavelength shift and the optical property stabilization of the reflection type photopolymer OmniDex film are studied as a function of pressure. As the center wavelength is changed from 632 nm to 482 nm, the bandwidth is 27％ broadened and the diffraction efficiency deviation maintained lower than 10％. These results show that the proposed color tuning method minimizes the change of optical properties more than 50％ compared with the diffusion-based method as the center wavelength changed from 511 nm to 630 nm. The press-based color tuning method shows that it could be used to make holographic optical elements that operate at wavelengths where lasers are not readily available for reflection type holographic recording.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.33-36
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• 2000

KrF excimer laser, which is useful for fabrication of fiber gratings, was irradiated on the PLC-type WDM directional coupler and the transmission wavelength shift was observed as a function of UV exposure time. The effective refractive index change of rectangular silica waveguide was calculated from the wavelength shift measurement and the coupled mode theory. heory.

• Korean Journal of Optics and Photonics
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• v.22 no.2
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• pp.67-71
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• 2011

In the paper, we have demonstrated an azobenzene-coated fiber Bragg grating (FBG) for monitoring ultraviolet light (UV) intensity in remote measurement. The elasticity of the coated azobenzene polymer is changed by the UV light, which induces a center wavelength change corresponding to the change of the FBG's grating period. The wavelength shift resulting from both UV light and other light with the wavelength out of the UV range was about 0.18 nm. In order to improve the accuracy of the measurement, the center wavelength shift caused by radiant heat of the light source was sufficiently removed by using a thermal filter. The amount of the center wavelength shift was consequently reduced to 0.06 nm, compared to the result without the thermal filter. Also, the FBGs coated by using azobenzene polymer were produced by two different methods; thermal casting and UV curing. Considering temperature dependence, UV curing is more suitable than thermal casting in UV sensor application of the azobenzene-coated FBG. In addition, we have confirmed the wavelength dependence of the optical sensor by means of four different band pass filters. Thus, we found out that the center wavelength shift per unit intensity is 0.029 [arb. unit] as a maximum value at 370 nm wavelength region and that the absorption spectrum of the azobenzene polymer was very consistent with the wavelength dependence of the azobenzene-coated FBG.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.35-45
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• 2016

Melatonin hormone involved in human's circadian rhythm adjustment sensitively responds to light's specific short wavelength ratio. A shift worker's circadian rhythm disturbance and sleep disorder are caused by the existing lighting conditions, whose short wavelength ratio is fixed. The life pattern of a shift worker changes irregularly because of irregular working hours and the same lighting environment; thus, his/her concentration is reduced. For such a reason, negative effects ensue to the detriment of healthy everyday life, including a high risk of accidents or having unsound sleep after leaving work. A smartphone-based wavelength control LED lighting system that targets shift workers and that can easily measure and control lighting suitable for wake-sleep cycle, according to working hours and closing hours, is proposed in this paper. First, after the light characteristics of LED lighting that changes depending on light control ratio are measured through the color sensor installed on the smartphone and the externally-linked Mini-Spectrometer, they are stored in the database. Based on the stored optical characteristics data, the measurement module and light control module are implemented. Lighting is offered using a control ratio having the maximum rate of short wavelength in consideration of the target illuminance, classified according to work type by identifying working hours as time when waking is required for shift workers. After a shift work leaves work, the amount of lighting is varied, using a control ratio having a minimum short wavelength rate so that a shift worker can enter the sleep state naturally.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.209-212
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• 2001

We Propose a novel structure add/drop multiplexer based on an all-fiber Mach-Zehnder interferometer and fiber Bragg grating. In this structure, wavelength separation is achieved by adjusting the amount of the phase shift in the Mach-Zehnder interferometer. The proposed add/drop multiplexer drops a part of signal at a specific wavelength and transmit the remnant of the signal to the different node separated wavelength in WDM network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1534-1541
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• 2000

Wavelength tunable fiber ring laser can be tuned by causing a resonance on the optical path having the least loss which is controlled by a polarization adjustment. It is observed that lasing wavelengths having 1 nm FSR(Free Spectral Range) can be tuned over the range of 1540-1560 nm when a polarization controller and an intra-cavit polarizer with 1.5 mm air gap are adjusted. The characteristics of wavelength shift in the laser output are analyzed by introducing an optical path modeling and the concept of a birefringence loss.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.901-907
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• 2000

As the minimum feature size for making ULSI approaches the wavelength of light source in optical lithography, the aerial image is so hardly distorted because of the optical proximity effect that the accurate mask image reconstruction on wafer surface is almost impossible. We applied the Optical Proximity Correction(OPC) on isolated patterns assuming Attenuated Phase Shift Mask(APSM) as well as binary mask, to correct the widening of isolated patterns. In this study, we found that applying OPC to APSM shows much better improvement not only in enhancing the resolution and fidelity of t도 images but also in enhancing the process margin than applying OPC to the binary mask. Also, we propose the OPC method of APSM for isolated patterns, the size of which is less than the wavelength of the ArF excimer laser. Finally, we predicted the resolution limit of optical lithography through the aerial image simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.1009-1011
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• 2012

In this paper, a wavelength tunable light source based on mutually injected locking with two F-P LDs, has been constructed and then analyzed for wavelength shift and RIN (Relative Intensity noise) according to temperature. We have measured maximum about 2 nm for the wavelength shift and minimum -110dB/hz for the RIN. Also, the RIN and beating noise in eye patterns are increased by changing temperature high.