• Current Optics and Photonics
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• v.5 no.2
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• pp.186-190
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• 2021

In this study, a compact, picosecond, mid-infrared 3.8 ㎛ MgO:PPLN optical parametric oscillator (OPO) laser output with high peak power is realized using a master oscillator power amplifier (MOPA) 1 ㎛ solid-state laser seeded by a picosecond fiber laser as the pump source. The pump source was a 50 MHz and 10 ps fiber seed source. After AOM pulse selection and two-stage solid-state amplification, a 1,064 nm laser output with a repetition frequency of 1-2 MHz, pulse width of 9.5 ps, and a maximum average power of 20 W was achieved. Furthermore, a compact short cavity with a unsynchronized pump is adopted through the design of an OPO cavity structure. When the injection pump power was 15 W and the repetition frequency was 1 MHz, the average output power of idler light was 1.19 W, and the corresponding peak power was 119 kW. The optical conversion efficiency was 7.93%. When the repetition frequency was increased to 2 MHz, the average output power of idler light was 1.63 W, the corresponding peak power was 81.5 kW, and the optical conversion efficiency was 10.87%. At the same time, the output wavelength was measured at 3,806 nm, and the beam quality was MX2 = 3.21 and MY2 = 3.34.

• ETRI Journal
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• v.23 no.1
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• pp.1-8
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• 2001

The performance of a long wavelength-band erbium-doped fiber amplifier (L-band EDFA) using 1530nm-band pumping has been studied. A 1530nm-band pump source is built using a tunable light source and two C-band EDFAs in cascaded configuration, which is able to deliver a maximum output power of 23dBm. Gain coefficient and noise figure (NF) of the L-band EDFA are measured for pump wavelengths between 1530nm and 1560nm. The gain coefficient with a 1545nm pump is more than twice as large as with a 1480nm pump. It indicates that the L-band EDFA consumes low power. The noise figure of 1530nm pump is 6.36dB at worst, which is 0.75dB higher than that of 1480nm pumped EDFA. The optimum pump wavelength range to obtain high gain and low NF in the 1530nm band appears to be between 1530nm and 1540nm. Gain spectra as a function of a pump wavelength have bandwidth of more than 10nm so that a broadband pump source can be used as 1530nm-band pump. The L-band EDFA is also tested for WDM signals. Flat Gain bandwidth is 32nm from 1571.5 to 1603.5nm within 1dB excursion at input signal of -10dBm/ch. These results demonstrate that 1530nm-band pump can be used as a new efficient pump source for L-band EDFAs.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.202-205
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• 2000

One step thermal potassium ion exchange process was carried out to form optical channel waveguides in an ErNb co-doped phosphate glass. Flowing oxygen gas into KN03 melt during ion exchange was effective to prevent glass surface damage that causes an increase of waveguide propagation loss. Amplification characteristics of the waveguides were evaluated at $1.5{\mu}m$ signal wavelength with 980 om laser diode pump. A 45 mm long waveguide whose processing parameters had been optimized exhibited a small signal net gain of 7.5 dB at the launched pump power of 160 mW.160 mW.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.170-176
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• 2008

According to the development of Internet, DWDM system needs to improve the performance for long distance transmission international optical signals. For higher the transmission capacity, we have to raise the transmission speed and increase a number of channels. To make qualifications, there are a lot of technologies such as line coding, modulation, precious fiber, broadband amplification, dispersion and forward error correction. Especially, FEC has been considered as a progressive technology for long distance transmission to carry out high speed and large capacity traffic. This paper introduced the progress of each new generation of FEC and the way to employ by current system analyzed the coding gain.

• 한국가스학회:학술대회논문집
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• 2006.11a
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• pp.123-128
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• 2006

This paper describes NDIR $CO_2$ gas sensor that shows the characteristics of temperature compensation. It consists of novel optical cavity that has two elliptical mirrors and a thermopile detector that includes ASIC chip in the same metal package for the amplification of detector output voltage and temperature sensor. The newly developed sensor modules shows high accuracy (less than +/-40 ppm) throughout the measuring concentration of $CO_2$ gas from 0 ppm to 2,000 ppm. After implementing the calculation methods of gas concentration, which is based upon the experimental results, the sensor module shows high accuracy less than +/- 5 ppm error throughout the measuring temperature range $(15^{\circ}C\;to\; 35^{\circ}C)$ and gas concentrations.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.515-520
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• 2003

Characteristics of an amplifier with repetition rate of a few KHz is investigated. The continuous flash lamp pumped Nd:YAG laser head is used as an amplifier. The thermally induced birefringence of the laser medium is compensated and the depolarization is reduced to 5% in a double-pass amplifier. The amplification factor of a four pass amplifier reaches to about 3.2 at the repetition rate 5-10 KHz and the pulse width is lengthened from 40 ns to 48 ns.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.163-164
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• 2003

현재의 OTDR 기술은 150km 이상의 광선로를 감시하기 어렵다. 이 문제를 해결하기 위하여 라만 증폭기를 사용하여 장거리의 기간 전송망을 감시할 수 있는 바이패스 모듈을 구성하였다. 1625nm 파장에서 11dB 이득을 갖는 라만 증폭기가 포함된 바이패스 모듈을 사용하여 300km의 광전송라인을 감시할 수 있는 기술을 확보하였다.

• 전기의세계
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• v.29 no.5
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• pp.321-328
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• 1980

The Q-switching oscillator of TE $M_{00}$ mode was constructed in order to improve the properties of energy focusing and amplification, and prevent laser materials from breakdown. The Q-switching was done by means of electro-optical effect using Glan prism and KDP Pockels cell. Sharp laser pulse of risetime-1 ns and variable pulse width 2-10 ns was obtained from Q-switching laser pulse by PTM method using a laser triggered spark gap (LTSG), Glan prism and Pockels cell. A single ultra-short pulse (picosec order in pulse width) was obtained from mode-locked pulse train in combination of a mode-locked oscillator using saturable dye cell with pulse shaping system using PTM method.d.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.471-475
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• 1997

We investigate the gain dynamics of erbium-doped fiber amplifiers during single- and multi-channel amplification. Power transients due to the changes in the number of channels in the amplifier chain are measured. We successfully suppress power transients by using a fast pump control circuit with<$\mu$s response time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.533-534
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• 2002

In this paper, we studied the transient gain response in TDFA(Thulium-Doped Fiber Amplifier) theoretically. We also investigated the limitation of the gain saturation and recovery time when the short pulse trains are incident into the TDFA with the spectral gain band in 1.47${\mu}{\textrm}{m}$ for using at WDM. We can predict the interval between the pulse train, pump power and the effect of the saturation and recovery time which is affected to the amplification of the optical pulse.