• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.8
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• pp.52-61
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• 1997

In this paper it is proposed a new architecture for N*N optical packet switching system. It consists of active-splitter type pf packet router, travelling type of optical buffer memory for packet contention resoltuion and an electronic controller. the BER performance of the proposed switching system is analyzed with respect to channel crosstalks and amplified spontaneous emissio noise form switching elements and optical amplifiers respectively. Operational validity of the proposed switching system is also experimentally proved by realizing 2*2 optical packet switching system.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.564-568
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• 2006

Using the cross-gain modulation (XGM) characteristics of semiconductor optical amplifiers (SOAs), multi-functional all-optical logic gates, including XOR, AND, and OR gates are successfully simulated and demonstrated at 10Gbit/s. A VPI component maker^TM simulation tool is used for the simulation of multi-functional all-optical logic gates and the10 Cbit/s input signal is made by a mode-locked fiber ring laser. A multi-quantum well (MQW) SOA is used for the simulation and demonstration of the all-optical logic system. Our suggested system is composed of three MQW SOAs, SOA-1 and SOA-2 for XOR logic operation and SOA-2 and SOA-3 for AND logic operation. By the addition of two output signals XOR and AND, all-optical OR logic can be obtained.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.135-138
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• 2003

A chirped-pulse amplification femtosecond Ti:sapphire laser operating at 1 KHz has been developed. The laser system consisted of a long-cavity femtosecond oscillator, a four-pass grating pulse stretcher, two multi-pass amplifiers and a double-pass grating pulse compressor. Thermal lensing at the amplifiers was reduced by cooling Ti:sapphire crystals using Peltier coolers. Gain narrowing and residual phase errors were compensated for by the use of an acousto-optic pulse shaper. The final laser output had an energy per pulse of 2.0 mJ and a pulse duration of 19.5 fs, reaching 0.1 TW at 1 KHz.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.59-63
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• 1990

Two-stage TEA(transversely excited atmospheric pressure) CO2 laser amplifier system, Amp I and Amp II are consturcted and their amplification characteristics are investigated theoretically and experimentally. Multiple-wire corona preionization method is used for uniform discharge in laser oscillator and amplifiers. At optimumm gas ratio, CO2 : N2 : He = 1 : 1 : 3, output pulse energy of the oscillator is 0.4J and finally two-stage amplification gives 1.5J output energy which is larger than pumping threshold of para-H2 Raman laser. The rate equations of the amplifiers are solved numerically, and the results are compared with the experimental results. In conclusion, the small signal gain cocfficient of AMP I is 0.025/cm and that of AMP II is 0.02/cm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.119-128
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• 1995

We report hybrid and passive mode-locking results of tilted-stripe AlGaAs semiconductor laser traveling wave amplifiers with saturable absorbers. Dependence ofthe pulse width on the mode locking frequency, the bandwidth of spectral filters, and the bias current of the laser amplifier are investigated. We generate 4 ps optical pulses by using the hybrid mode locking technique. The repetition rate and the peak power of generated pulses are 516 MHz and 170 mW, respectively. The tuning range of uor mode locked laser is 10 nm with the center wavelength of 780 nm. We also generate 2.6 ps optical pulses with peak power of 830 mW by using the passive mode locking technique.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.81.2-81.2
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• 2000

• Ceramist
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• v.10 no.3
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• pp.28-33
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• 2007

The structural and optical properties of Ni-doped transparent glass-ceramics are reviewed. The quantum efficiencies of ceramics were examined to explore suitable crystalline phase for Ni-doping in glass-ceramics. Inverse spinel $LiGa_5O_8$ have the quantum efficiency of almost 100 % at room temperature. Transparent glass ceramics containing $LiGa_5O_8$ was successfully synthesized by heat treatment of $Li_2O-Ga_2-O_3-SiO_2-NiO$ glass. Most of $Ni^{2+}$ ions in glass-ceramic were incorporated into $LiGa_5O_8$ nanocrystals. The near-infrared emission covering from the O-band to L-band (1260-1625 nm) was observed from the Ni-doped $Li_2O-Ga_2O_3-SiO_2$ glass-ceramic though it was not observed from the as-cast glass. The lifetime of the emission was about $580\;{\mu}sec$ even at 300K. The emission quantum efficiency was evaluated as about 10 % that is enough high for practical usage as gain media of optical fiber amplifiers. The figure of merit (the product of the stimulated emission cross section and lifetime) was as high as that of rare-earth-doped glasses. The broad bandwidth, high quantum efficiency and high figure of merit show that transparent glass-ceramics containing $Ni^{2+}:LiGa_5O_8$ nanocrystals are promising candidates as novel ultra-broadband gain media.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.122-130
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• 2015

This paper presents a 6 Gb/s 4-channel arrayed transimpedance amplifiers (TIA) with the gain control for 4-channel passive optical network in $0.13{\mu}m$ complementary metal oxide semiconductor (CMOS) technology. A regulated cascode input stage and inductive-series peaking are proposed in order to increase the bandwidth. Also, a variable gain control is implemented to provide flexibility to the overall system. The TIA has a maximum $98.1dB{\Omega}$ gain and an input current noise level of about 37.8 pA/Hz. The die area of the fabricated TIA is $1.9mm{\times}2.2mm$ for 4-channel. The power dissipation is 47.64 mW/1ch.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.7 s.337
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• pp.1-4
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• 2005

A four-channel photoreceiver ways have been realized in a 0.8$\mu$m Si/SiGe HBT technology for the applications of parallel optical interconnects. The receiver array includes four-channel transimpedance amplifiers (TIAs) and p-i-n photodiodes, where the TIAs exploit a common-emitter (CE) input configuration. Measured results demonstrate that the four-channel CE TIA array provides 3.9GHz bandwidth, 62dB$\Omega$ transimpedance gain, 7.5pA/sqrt(Hz) average noise current spectral density, and less than -25dB crosstalk between adjacent channels with 40mW power dissipation.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.340-346
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• 2000

Traveling wave type semiconductor optical amplifiers integrated with spot-size-converter (SSC-TW-SOA) have been extensively studied for the improvement of coupling effiClency With single-mode fiber and fO! the cost reducClon 111 a packaging In tlIis paper the slructural dependence of the spot-slZe-converter on the effective facet reflectlvllY $R_{eff}$ was experimentally as well as thcoretienlly mvestlgated. It was shown that not only a sufficient mode-conversion in a sse region along the latersl and tran~verse directions but also an introductIOn of angled-facet were very essential in order to reduce $R_{eff}$ Very small ripple less than 0.1 dB in an amplified spontaneous emission spectrum was observed with the fabncated SSC-lW-SOA which consists of the wrndow length of $20\mu\textrm{m}$, facet angle of $7^{\circ}$, and antlrelleetioll-coated facet of ] % reflectivity.tivity.