• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.431-436
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• 2001

The effect of decorrelation on the coincidence is investigated with correlated photons produced by parametric down-conversion process. The degree of correlation between photon pairs is adjusted by changing the polarization dependent transmissivities of thin glass plate\ulcorner in front of two detectors. It was found that the single counts of each detectors are proportional to the transmissivity and the coincidence is proportional to the product of transmissivities of the glasses in front of two detectors.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.406-413
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• 2001

We report theoretical and experimental results for the wavelength and polarization selectivity of a fiber-to-planar waveguide coupler made of a side polished single mode fiber covered with a planer waveguide incorporating a thin metal film. A simple but exact approach to obtain the modal properties of multilayer planar waveguide with a thin metal film is described. The device was modeled into equivalent 1 dimensional structure and its behaviour was analyzed based on coupled mode theory. The effects of metal film thickness and refractive index of superstrate on the device properties were measured and explained.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.40-47
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• 2001

The structural dependence of the performance of an 1.55 $1.55{\mu}m$ InGaAsPIInGaAsP MQW electro-absorption modulator for highspeed digital fiber communication was systematically investigated. The effects of n-doped SCH region length $t_n$ as well as the general structure parameters including quantum well number $N_w$, well-thickness $t_w$, detuning wavelength $\Delta\lambda$, and device length L were thoroughly analyzed. Thereby, a high-pelfoIDlance electro-absorption modulator with device length L of $100{\mu}m$ was successfully designed. The designed structure showed excellent characteristics that have residual loss less than -1.5 dB, operational voltage from 0 V to -2V, and extinction ratios of -2.92 dB at $V_{\alpha}$=-1 V and -10 dB at $V_{\alpha}$=-2V.X>=-2V.

• Journal of Magnetics
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• v.21 no.1
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• pp.20-24
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• 2016

Magnetic properties of bio-magnetic molecule ferritin have been investigated. Two ferritin samples were synthesized under different magnetic fields, 0 and 9.4 T, respectively. This work is focused on the influence of magnetic field on biomineralization process. While magnetization vs. temperature (M-T) data of both samples measured at 1000 Oe are almost identical except for low temperature region (T < 6 K), magnetization vs. field (M-H) data show noticeable difference. From an analysis of M-H data by using a modified Langevin function, we could extract the saturation magnetization $m_0$(T), the effective magnetic moment ${\mu}_{eff}$(T) and the linear susceptibility x(T). The difference between the samples is most prominent in the x(T), whereby the x(T) of the sample prepared at 9.4 T is 1.7 times bigger than that of the other. In addition, from hysteresis and relaxation measurements, we found the sample prepared at 9.4 T showed strikingly smaller coercivity and slower relaxation.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.15-20
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• 2002

We demonstrate a widely-tunable wavelength converter based on four-wave mixing in a semiconductor-fiber ring laser with no external pump light. Applying 10 GHz short pulses at -8 dBm as a probe signal, we achieve continuous wavelength tuning over the semiconductor optical amplifier gain-bandwidth reaching 30 nm down- and 17 m up-wavelength conversion. In addition to the wide tuning capability, the converter shows high-speed conversion and low saturation power capabilities.