• Journal of Korean Ophthalmic Optics Society
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• v.6 no.1
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• pp.101-105
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• 2001

It was measured the transmittance and the reflectance by tie dip method using the UV cut lens' UV solution. The half point and the edge wavelength of the transmittance were wry well applied to the eqution of a dip time dependence. $$W=W_0+A_1{e}{x}{p}[-(x-x_1)/t_1]$$ The half point wavelength of the transmittance shifted from 358 nm to 408 nm and the edge wavelength moved from 340 nm to 398 nm. The more dip time had long the less intensity of main reflectance peak-380 nm was small and shifted to long wavelength regions. And the component peak of UV solution began to show in dip time-10 min.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.389-393
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• 2001

A wavemeter is realized using the fact that the coupling coefficient of a WDM coupler is a function of wavelength. Prototype devices with 1500 nm/1600 nm and 1510 nm/1550 nm WDM couplers are successfully fabricated and tested in the laboratory. The measurement resolutions are $\pm$0.27 nm over a wavelength range of 1515 nm~1576 nm for the device with 1500 nm/1600 nm WDM coupler and $\pm$0.103 nm over a wavelength range of 1520 nm~1543 nm for th4e device with 1510 nm/1550 nm WDM coupler. The dependence of operating characteristics on the input signal power is insignificant. However the temperature dependence is ~0.06 nm/$^{\circ}C$.

• ETRI Journal
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• v.9 no.2
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• pp.55-61
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• 1987

The effective cutoff wavelength of $LP_11$mode is measured as a function of fiber length for three types of single-mode optical fiber which have different characteristics in the index profile or the coating structure. The measured cutoff wavelength decreased linearly in a logarithmic scale of fiber length as increasing fiber length, and eventually became constant after 3km for two fiber types. It is found that the length dependence of cutoff wavelength is due to a mode coupling between the $LP_01$ and $LP_11$ modes.

• Current Optics and Photonics
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• v.4 no.6
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• pp.558-565
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• 2020

A wavelength-independent optical sensor based on an asymmetric Mach-Zehnder interferometer (AMZI) is proposed. The optical sensor based on an AMZI is very sensitive to wavelength, and wavelength drift will lead to measurement error. The optical sensor is compensated to reduce its dependence on wavelength. The insensitivity of the optical sensor to wavelength mainly depends on the compensation structure, which is composed of an AMZI cascaded with another AMZI and can compensate the wavelength drift. The influence of wavelength drift on the optical sensor can be counteracted by carefully designing the size parameters of the compensation structure. When the wavelength changes from 1549.9 nm to 1550.1 nm, the error after compensation can be lower than 0.066%. Furthermore, the effect of fabrication tolerance on compensation results is analyzed. The proposed compensation method can also be used to compensate the drift of other parameters such as temperature, and can be applied to the compensation of other interference-based optical devices.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.895-898
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• 2014

The wavelength dependence of the photoacoustic signal for n-type GaAs semiconductors in the region of the band-gap energies was investigated. The significant changes in the phase and amplitude of the photoacoustic signal near the band-gap absorption wavelengths were observed to occur when the Si-doping densities in GaAs were varied. Particularly, the first derivatives of the photoacoustic phase vs. wavelength graphs were evaluated and fitted with single Gaussian functions. The peak centers and the widths of the Gaussian curves clearly showed linear relationships with the log values of the Si-doping densities in n-type GaAs semiconductors. It is proposed that the wavelength-dependent PA spectroscopy can be used as a simple and nondestructive method for measuring the doping densities in bulk semiconductors.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.801-805
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• 2004

In this work, the fundamental study of on-line monitoring of $SiO_2$ particles in the size range of 40 nm to 725 nm was carried out using turbidimetry. The size of particle was measured using a field emission scanning electron microscope (FE-SEM). The factors affecting on the turbidity were discussed, for example, wavelength, size, and concentration. In order to observe the dependence of turbidity on the wavelength, a turbidimetric system equipped with charged coupled detector (CCD) was built. The shape of the transmitted peak was changed and the peak maximum was shifted to the red when the concentration of particle was increased. This result indicates that the turbidity is related to the wavelength, which corresponds to the characteristic of the Mie extinction coefficient, Q, that is a function of not only particle diameter and refractive index but also wavelength. It is clear that a linear calibration curve for each particle in different size can be obtained at an optimized wavelength.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• Korean Journal of Optics and Photonics
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• v.23 no.6
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• pp.251-254
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• 2012

Dual-wavelength holography has a better axial range than single-wavelength holography, allowing unambiguous phase imaging. The size of a reconstructed image depends on the reconstruction distance and wavelength. The two phase image sizes of different wavelength holograms should be the same in order to apply dual-wavelength holography. The Fresnel-Bluestein transform method is proposed to eliminate the dependence on the reconstruction distance and wavelength. We found that the Fresnel-Bluestein transform is very useful for making different reconstructed image sizes experimentally. Also we applied the Fresnel-Bluestein transform to make the same reconstruction image size in dual wavelength holography.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.214-215
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• 2004

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.135-141
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• 2003

In arrayed waveguide grating (AWG) devices whose waveguides were composed of polymer with negative thermo-optic coefficient as overcladding, and silica with positive thermo-optic coefficient as both core and undercladding, we investigated the temperature dependence of the central wavelength using two-dimensional SFDM. From these results, it was confirmed that the temperature dependence can be nearly eliminated by adjusting the refractive index of the cladding and the thickness of the silica thin film upper-loaded on the core. Based on the numerical calculations, the AWG device with polymer overcladding was fabricated. and its optical characteristics were compared with those of the orginal silica AWG device. The introduction of polymer overcladding decreased the temperature dependence of the central wavelength from 0.0130 nm/$^{\circ}C$ to 0.0028 nm/$^{\circ}C$ without deteriorating the insertion loss and crosstalk characteristics.