• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.317-322
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• 2010

This study used 4-fluorostyrene with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Measurement of the physical properties of the copolymerized polymer showed that the water content was 19.98 ~ 31.08%, refractive index 1.443 ~ 1.475, visible transmittance 87 ~ 93% and tensile strength 0.246 ~ 0.311 kgf while the contact angle showed a distribution between $54.14^{\circ}$ and $66.95^{\circ}$. Therefore, the ophthalmic material produced using 4-fluorostyrene satisfied the basic physical properties required for contact lenses and also showed an increase in wettability and refractive index while having no significant change in water content with relation to styrene. Based on the results of this study, the produced copolymer is suitable for use as a material to high refractive index and wettability contact lenses.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.172-179
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• 2020

We studied an integrated-optic biosensor configuration that operates at a wavelength of 0.63 ㎛ based on the evanescent-wave and two horizontal mode power coupling of Si₃N₄ rib-optical waveguides formed on a Si/SiO₂/Si₃N₄/SiO₂ multilayer thin films. The sensor consists of a single-mode input waveguide, followed by a two-mode section which acts as the sensing region, and a Y-branch output for separating the two output waveguides. The coupling between the two propagating modes in the sensing region produces a periodically repeated optical power exchanges along the propagation. A light power was steered from one output channel to the other due to the change in the cladding layer (bio-material) refractive index, which affected the effective refractive index (phase-shift) of two modes through evanescent-wave. Waveguide analyses based on the rib optical waveguide dimensions were performed using various numerical computational software. Sensitivity values of 12~23 and 65~165 au/RIU, respectively for the width and length of 4 ㎛, and 3841.46 and 26250 ㎛ of the two-mode region corresponding to the refractive index range 1.36~1.43 and 1.398~1.41, respectively, were obtained.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.402-407
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• 2017

Characteristics of various material surface plasmon resonance (SPR) chips were investigated in angular interrogation mode and intensity interrogation mode. Among five metals, silver (Ag), gold (Au), copper (Cu), chromium (Cr) and titanium (Ti), three metals, Ag, Au and Cu were paid attention to since their characteristics can be easily analyzed in angular interrogation mode by investigating the change of their reflectance curves according to refractive index change from 1.331 to 1.335. Most of SPR chips with various configurations showed the similar property in angular interrogation mode. The application of the SPR chip made of Ag, Au and Cu or their combinations depends on their reflectance properties. In intensity interrogation mode, the operation range may be limited since the variation of the intensity was not linearly related to refractive index change ranging from 1.331 to 1.335. However, the SPR chip containing high ratio of Ag may be applicable to high sensitive detection due to their sharp reflectance curves in intensity interrogation mode.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.345-351
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• 1995

We have studied experimentally the propagation characteristics of fundamental dark spatial solitons on finite-width backgrounds and conpared with the result of numerical simulations. It was verified experimentally that the width of dark solitons decreased but that of background increased as the beam intensity increased. The refractive index change obtained from soliton constant, which is for infinite-width background, was smaller than that from Z-scan method. Numerical simulations of fundamental dark solitons on a finite-width backgrounds showed that the peak intensity of background, the width of dark soliton and the soliton constant varied with the propagation length. If the change of soliton constant on finite-width backgrounds was considered, the refractive index change was in good agreement with that from Z-scan method. ethod.

• Korean Journal of Optics and Photonics
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• v.31 no.6
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• pp.314-320
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• 2020

The optics used in an infrared imaging system has a strong refractive-index change according to temperature, so an autofocus control function is essential for a military infrared imaging system with a wide operating-temperature range. In this study, we design a triple-magnification infrared imaging system, and to compensate for the change in refractive index according to temperature we measure the change in the lens focus according to temperature. The autofocus control function was implemented by using the measured movement amount, and we could obtain an image with satisfactory resolution performance over a wide range of operating temperatures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.157-162
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• 2023

A highly sensitive refractive index bio-sensor based on grating-assisted strip directional coupler (GASDC) is proposed. The sensor is designed using two asymmetric strip waveguides with a top-loaded grating structure in one of the waveguides. Maximum light couples from one waveguide to the other at the resonance wavelength satisfying phase-matching condition (PMC), and it shows that the change in phase-matching condition with the change in refractive index of the analyte medium in the cover region can be used as a measure of the sensitivity. The proposed sensor will be an on-chip device with a high refractive index sensitivity, and the sensor configuration offers a low propagation loss, thereby enhancing the sensitivity. Furthermore, variation of the sensitivity with the waveguide parameters of sensor is evaluated to optimize the design.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.37-41
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• 2005

The curing of thermoset resin is accompanied with the changes in chemical and physical properties. The cure monitoring techniques can be designed by tracing these property changes. This paper presents the cure monitoring technique with fiber optic sensors to detect the change of refractive index during the polymerization process of engineering epoxy resin. The fiber optic sensor system was developed to measure the reflection coefficient at the interface between the fiber optic and the resin. The correlation between the sensor output and the degree of cure was performed following Lorentz-Lorenz law. The isothermal data from the sensors are compared with the data from differential scanning calorimeter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.195-198
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• 2014

In this paper, a measurement method to obtain the optical properties of a liquid base on a side-polished single mode fiber was proposed and demonstrated. The device showed periodic resonance coupling against wavelengths. The refractive index and dispersion characteristics of a liquid were calculated by use of the spacings of periodic resonance wavelengths of the device. The thermo-optic coefficient of the liquid was obtained by monitering the shift of resonance wavelengths of the devices with change of environmental temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.808-811
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• 2008

Optical and mechanical properties of diamond-like carbon (DLC) films synthesized by RF plasma enhanced chemical vapor deposition were investigated as a function the C/H ratio in gas mixture. The C/H ratio was varied from 6 to 10 %, adjusting the amount of $CH_4$ and $H_2$ as the source gas. The optical and mechanical properties of DLC films were characterized by UV spectrometer, Ellipsometer and Nano-indenter. The change of the C/H ratio during synthesis of DLC films had many effects on the growth rate, transmittance, refractive index and hardness. The growth rate of the films increased exponentially with the increase in C/H ratio. The hardness of the films showed the tendency to improve with increasing C/H ratio, whereas the transmittance decreased. The refractive index was varied from 2.03 to 2.17, and these refractive indexes close to 2.0 indicates that it can be applied to Si-based solar cell.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.79.2-79.2
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• 2000