• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.285-286
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• 2006

• Korean Journal of Optics and Photonics
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• v.2 no.2
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• pp.67-73
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• 1991

The unsaturated signal gain, signal gain bandwidth, and saturation power which are important parameters determining characteristics of the semiconductor laser amplifier were measured for an AlGaAs Fabry-Perot cavity type laser amplifier and compared with the results of Fabry-Perot formula. The unsaturated signal gain 25 dB is obtained near oscillation thereshold current at $0.7\mu\textrmW$ input power. The corresponding signal gain bandwidth was about 3 GHz. Also. We measured the variation of the saturation signal gain and saturation power.

• Journal of the Optical Society of Korea
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• v.4 no.2
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• pp.75-78
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• 2000

We design a high temperature oven for measuring the saturation intensity of the transition line $4f^ 6/6s^{2 7}7F_0 ↔ 4f^6/6s6p $^1$P(J = 1)$ of the samarium atom. We first constructed a high temperature oven to generate the samarium vapor column and study the thermal characteristics of the oven. The oven is able to operate at a temperature up to about 1400 $^{\circ}C$ and the operation is tested by using several metals with high melting points. We describe two wave mixing experiment with the samarium vapor generated in the high temperature oven and obtain the saturation intensity by analyzing the first diffraction signal.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.97-101
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• 2002

The optical current transformer using Faraday effect is the sensor to measure current that flows in any conductor. This sensor doesn't undergo the magnetic saturation and effect of adjacent conductors. But this senor using bulk-glass sensing element has crucial drawback. It is impossible that the sensor is mounted to conductor without breaking the closed-loop of light or conductor. So we developed the clamp-type optical current transformer and made an experiment.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.499-500
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• 2009

• Current Optics and Photonics
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• v.2 no.6
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• pp.563-567
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• 2018

We propose and experimentally demonstrate a simple tunable photonic microwave band-pass filter with high resolution using a reflective semiconductor optical amplifier (RSOA) and an optical time-delay line. The RSOA is used as a gain medium for generating cross-gain modulation (XGM) effect as well as an optical source. The optical source provides narrow spectral width by self-injection locking the RSOA in conjunction with a partial reflection filter with specific center wavelength. Then, when the RSOA is operated in the saturation region and the modulated recursive signal is injected into the RSOA, the recursive signal is inversely copied to the injection locked optical source due to the XGM effect. Also, the tunability of the passband of the proposed microwave filter is shown by controlling an optical time-delay line in a recursive loop.

• Journal of Magnetics
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• v.12 no.3
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• pp.129-132
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• 2007

Bismuth-substituted yttrium iron garnet (Bi:YIG, $Bi_{0.5}Y_{2.5}Fe_5O_{12}$) films were deposited with aerosol deposition method and their magnetic and optical properties were investigated as a function of annealing temperature. Since the ceramic films deposited with aerosol deposition method have not a perfect crystal structure due to non-uniform internal stress occurred by mechanical collision during their deposition, the post annealing could be a key process to release its internal stress and to improve its micro structure for optimizing the magnetic and magneto-optic properties of films. The crystallinity of Bi: YIG film was improved with increase of annealing temperature, and the saturation magnetization increased up to 87 emu/cc at $800^{\circ}C$. The Faraday rotation increased up to $1.4deg/{\mu}m$ by annealing at $700^{\circ}C$ around the wavelength of $0.5{\mu}m$. The optical transmittance of the Bi:YIG film was also improved in visible region.

• Current Optics and Photonics
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• v.7 no.1
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• pp.28-32
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• 2023

Frequency characteristics of gain-saturated erbium-doped fiber amplifier (EDFA) are experimentally evaluated to mitigate the optical signal fluctuation induced by atmospheric turbulence in terrestrial freespace optical communication systems. Here, an acousto-optic modulator (AOM) is used to emulate optical signal fluctuations induced by atmospheric turbulence. The waveform which is generated in proportion to the refractive-index structural parameters is used to drive the AOM at various periodic frequencies. Thus, the dependence of the signal fluctuation suppression on the frequency is evaluated. The experiment is conducted using a periodic frequency sweep of the AOM driving voltage waveform and signal input power variation of the amplifier. It is observed that a low periodic frequency and high input signal power effectively suppress the optical signal fluctuation. This study evaluates the experimental results from the high-pass filter and gain-saturation characteristics of the EDFA.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.305-311
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• 2006

We propose a 7-level atom model, which takes into account two-photon coherence effects in saturation absorption spectroscopy. Using this model we explained spectral change with laser intensity and some of crossover resonance lines, which cannot be explained with Nakayama theory. The 7-level model consists of two upper levels and five lower levels, which account for $\pi-\pi$ polarization of both pump and probe beams in Zeeman sub levels. We compared our 7-level model with 4-level Nakayama theory for 5S$_{1/2}$ - 5P$_{1/2}$ transition line in $^{85}$Rb atoms. The results of the 7-level model calculation agree well the saturation absorption spectra data according to laser intensities.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.267-270
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• 1997

Oxygen saturation is an important parameter in clinical fields; fetal monitoring, apnea, emergency medicine etc. Because of monitoring patients continuously, pulse oximeter that measures oxigen saturation non-invasively is regarded attentively. But, though research about accuracy of signal extraction has been developed, it actually plays a supplementary part in hospital for not trusting the principle of measurement by clinicians. In this paper focusing on these things, first we suggested simple mathematical modelling on separating do components, ac components andnoise components in optical signal transmitted from fingertip or earlobe, and then we considered oxygen saturation computing algorithm using integral ratio of pulsating components. Last, we analyzed its effect by comparing received data.