• Current Optics and Photonics
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• v.2 no.4
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• pp.356-360
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• 2018

We demonstrate continuous-wave operation of an all-fiber thulium-holmium codoped laser operating at a wavelength of 1706.3 nm. To realize laser operation in the short-wavelength region of the emission-band edge of thulium in silica fiber, we employ fiber Bragg gratings having resonant reflection at a wavelength around 1700 nm as a wavelength-selective mirror in an all-fiber cavity scheme. We first examine the performance of the laser by adjusting the central wavelength of the in-band pump source. Although a pump source possessing a longer wavelength is observed to provide reduced laser threshold power and increased slope efficiency, because of the characteristics of spectral response in the gain fiber, we find that the optimal pump wavelength is 1565 nm to obtain maximum laser output power for a given system. We further explore the properties of the laser by varying the fiber gain length from 1 m to 1.4 m, for the purpose of power scaling. It is revealed that the laser shows optimal performance in terms of output power and slope efficiency at a gain length of 1.3 m, where we obtain a maximum output power of 249 mW for an applied pump power of 2.1 W. A maximum slope efficiency is also estimated to be 23% under these conditions.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.491-498
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• 1996

The development of a compact two-wavelength Nd:YAG laser for dental and ENT applications is presented. The Nd:YAG resonator generates either 1.06$\mu$m or 1.32$\mu$m. The wavelength selection is made at the control panel. The Nd:YAG laser parameters at 1.06$\mu$m are ; the maximum pulse duration of 150$\mu$s, repetition rates of I-100Hz, and the maximum average power of 25W. At 1.32$\mu$m, the pulse duration is the same where the repetition rates and the maximum average power are I-30Hz and lOW respectively. High voltage power supply consists of a simmer module and two identical high voltage DC converters. In order to make a complete medical laser system, an optical fiber delivery unit, foot pedal and water spray handpiece are also developed. The wavelength selection is reliable since no movement of optical or mechanical components is required. The high voltage power supply is compact, easy to be maintained and applicable for other laser systems due to its modular design.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.69-75
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• 1998

We demonstrate wavelength conversion of 2.5Gb/s optical signals by four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We investigate the effect of input pump and signal powers on the coversion efficiency, optical signal-to-noise ratio (OSNR) and extinction ratio to be a measure of performance in a wavelength converter. As a result, we show that the maximum bit error rate (BER) performance can be obtained by co promising among high-vonversion efficiency (minimum Pprobe), high-OSNR (maximum Pprobe) and low-cross-gain saturation effects (Pprobe kept at least 6dB weaker than Ppump). In our experiment, we obtain optimum performance at +3 dBm pump power and -6dBm signal power. The power penalty incurred in the wavelength conversion can be minimized by careful selection of the input pump and signal powers. We show that about 0.5dB power penalty for 3.2nm wavelength coversion at 10-10 BER is achievable.

• International journal of advanced smart convergence
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• v.4 no.1
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• pp.99-103
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• 2015

Quake wavelength technique was designed of the sway by the body. There was presented a concept of the dangle wavelength by twisting condition of posture. We compared to the twisting condition for an average variation and maximum variation with the movement. There was used a combination system and correlation system of the posture. Their correlation signal was presented a control data by the dynamic movement. The quake wavelength system was to be formation of activity aspects by posture. The correlation of wavelength technique was applied to the a little action of posture variation signal. Quake wavelength by the dynamic movement was determined to a variation of vision condition of the $Vi-{\alpha}_{AVG}$ with $(-1.27){\pm}(-0.34)$ units, that vestibular condition of the $Ve-{\alpha}_{AVG}$ with $(-0.49){\pm}(-0.4)$ units, that somatosensory condition of the $So-{\alpha}_{AVG}$ with $0.037{\pm}0.269$ units, that CNS condition of the $C-{\alpha}_{AVG}$ with $(-0.049){\pm}0.015$ units. As the study of the quake wavelength technique was depended on the action system of body movement that a maximum and averag values was used a movement of combination data. The system was required an action signal for the form of actual signal on the basis of a little movement condition in the body. The human action systemwas compared to maximum and average from the movement derived the body. Therefore, their system was controlled to evaluate posture condition for the body correlation.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.310-315
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• 2003

The dyeing of cotton fabric with Forsythia koreana NAKAI was investigated. The colorant was extracted with methanol under various concentrations of dyestuffs at $40^\circ{C}$ and $76^\circ{C}$. UV-VIS spectrum was obtained to find the maximum wavelength of colorant. Cotton fabrics were dyed at different temperatures, mordants, in pre and post mordanting methods. The maximum wavelength of spectrum were 390nm, 410nm, 440nm. The highest K/S value was showed at 100% dye concentration, extracted at $76^\circ{C}$ and dyed at $80^\circ{C}$. The mordant effect was not good in the K/S values. The light fastness was increased at Fe-pre mordant and Cr, Fe-post mordant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7B
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• pp.417-426
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• 2005

Routing and wavelength assignment problem is one of the most important issues in optical transport networks based on wavelength division multiplexing(WDM) technique. In this paper, we propose a novel approach using path conflict graphs and an algorithm for finding all edge disjoint paths. And then we compare the performance of the proposed algorithm with that of bounded greedy approach for EDP(BGAforEDP). The proposed one outperforms up to about 20$\%$ in the fixed traditional topology(NSFNET) and about 32$\%$ in random topologies over the BGA for EDP algorithm.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.330-334
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• 2009

A simple and compact frequency swept laser is demonstrated at $1.3{\mu}m$ using a wavelength scanning filter based on a rotating slit disk. The laser is comprised of a pigtailed semiconductor optical amplifier, a circulator, and a wavelength scanning filter in an extended cavity configuration. The wavelength scanning filter is composed of a collimator, a diffraction grating, a rotating slit disk, and a mirror. The instantaneous laser output power is more than 5 mW. The scanning range of the laser is extended to 80 nm at the maximum level, and 55 nm in the full width at half maximum at a scanning rate of 2 kHz.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.6
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• pp.58-64
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• 1997

The wavelengt lockin gsystem of the optical fabry-perot filter theoretially derived and experimentally realized by using the ithering method in order to compensate the laser wavelength drift increasing the BER of the WDM system. The deviation between the laser wavelength and the optical filter center wavelength is compensated by applying a suitable voltage to the PZT. Accordingly, the laser wavelength selected by the fabry-perot filter always maintains the condition of maximum transmission powr. A wavelength locking system has been demonstrated using a fiber fabry-perot filter with a free spectral range of 80nm and an FWH of 1nm. The voltages of the sine wave generated for dithering was 20mV and 10mV, the frequency was 2kHz and center wavelength of the tunable laser was 1550nm. In this paper, the locking system have 20ms of locking time and 2nm of locking range.

• Fashion & Textile Research Journal
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• v.6 no.6
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• pp.799-802
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• 2004

The dyeability of the cotton fabric with Brassica campestris extract was investigated. The colorant was extracted with methanol. Cotton fabrics were dyed at various conditions such as temperatures, concentrations, dyed times, and mordanting methods. The maximum wavelength of extract was 421nm. The highest K/S value was showed at 200% dye concentration at $60^{\circ}C$, 45 minutes. As the effect of dyed temperature and mordanting on dyeability was not great, the Brassica campestris was one-color dyestuff.

• Textile Coloration and Finishing
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• v.12 no.5
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• pp.288-294
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• 2000

The dyeing of Tencel fabric with Coptis chinensis Franch was studied. The colorant was extracted with distilled water under various concentrations of dyestuff, times, mordants. UV-VIS spectra were obtained to find the maximum wavelength and absorbance of colorant. Tencel fabric was dyed with different mordants in pre and post-mordanting methods. Maximum wavelength of spectrum was 343 nm, and K/S value of pre-mordant was higher than post-mordant. Aluminium and stannic mordants changed color from yellow to blue-greenish and red-bluish. Colorfastnesses of light, and washing were low grade, but that of perspiration was increased.