• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.87-96
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• 1999

For analog optical transmission of narrow-band microwave signal, a novel all-optical linearization technique of electro-absorption (EA) optical modulator by using dual modulation scheme is proposed and theoretically investigated. By using the dual modulation scheme where the sub-modulator has a different length, DC bias and band-gap wavelength, the DC bias operation point where the third-order intermodulation products of ~30dB and the following increase of spurious free dynamic range (SFDR) of ~20dB wave achieved in sub-octave narrow band operation.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.135-136
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• 2009

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.110-117
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• 1998

An optical modulator with CPW(coplanar waveguide) electode on Ti:LiNbO$_{3}$ optical waveguide wasfabricated and characterized. The electrical-optical bandwidth measurement showed an optical response of -3dBat 10 GHzand S$_{11}$ lessthan -10dB upto 20GHz. The typeical specifications are : 5.6V of driving voltage, 4.2dB of insertion loss and 30dB of on/off extinction. The eye pattern proved that the optical meduator, fabricated in this work, has properties good enough for application.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.400-404
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• 2000

All-optical clock recovery from a 10 Gb/s RZ signal has been demonstrated using an actively mode-locked figure-eight laser incorporating a semiconductor optical amplifier in the loop-mirror scheme. Optical pulses with 10 ps pulse width were modulated by a LiNb03 external modulator at $2^{23}-1$ PRES and injected into the clock recovery circuit to extract optical pulses with 12 ps width. Regeneration of the original bit pattern has been accomplished by modulating the recovered clock with the same modulator, and no power penalty was observed at $10^{11}$..

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.119-123
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• 2010

The transmission performance of 10Gb/s optical duobinary transmitters implemented by using a Mach-Zehnder(MZ) modulator and an optical delay interferometer is presented. We investigated the theoretical impact of transmission systems by the modulator driving voltage ratio(=driving voltage/switching voltage) and the optical interferometer time delay to improve transmission distance using computer simulation. By reducing the driving voltage ratio and optimizing the partial bit time delay, the transmission performance has been improved greatly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.95-96
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• 1998

An optical modulator with CPW electrode on Ti:LiNbO$_3$ optical waveguide was fabricated and chterized. The electrical-optical bandwidth measurement showed an optical response of -3dB at 10 GHz and S11 less than -l0dB unto 20GHz. The typical specifications are . 5.6V of driving voltage, 4.2dB of Insertion loss and 30dB of on/off extinction.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.243-247
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• 1999

We report the generation of inherently stable, high-speed, nearly transform-limited, optical pulses by chirped pulse compression, in which sinusoidally driven phase modulator generates frequency chirped pulses that are subsequently compressed by a dispersive optical fiber. Experimental results show that $sech^2$ shape pulses with a pulse width of ~14 ps and a time bandwidth product of ~0.34 are successfully generated at 10 GHz repetition rate. In contrast to other methods, such as higher order soliton compression, this approach does not depend on the optical power and thus shows promise for application to low-power lasers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.5
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• pp.347-356
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• 2001

The issues that influence the packaging of high-speed LiNbO$_{3}$ modulators are discussed, and packaging approaches that result in only minor degradation of the modulator's RF performance are described. The primary problems dealt in this paper, associated with high-speed device packaging, are fallen into the following five categories: die features, pigtailing, suppression of RF package resonance, RF launcher approach, termination approach. By considering factors to influence the modulator performance in packaging, a LiNbO$_{3}$ intensity modulator was fabricated and packaged to have S21 better than -3㏈ upto 10㎓ and S11 below -l5㏈ upto 18㎓.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.37-45
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• 2002

In this paper, the microwave characteristics of traveling-wave electroabsorption coplanar waveguide modulator have been analyzed and optimized precisely by using the 3-dimensional finite-difference time-domain method (FDTD). Microwave characteristics are affected by the thickness of intrinsic layer, the width of meas, and the distance between signal electrode and ground electrode on traveling-wave type structure. In case that intrinsic layers are composed of InAsP/InGaP (1.3Q), the optimized distance between signal electrode and ground electrode, the optimized intrinsic region thickness and the width of waveguide are founded to be $3{\mu}m,\;039{\mu}m\;and\;2{\mu}m$, respectively, to minimize microwave loss and to obtain velocity and impedance matched structure. By using the FDTD, we could design the traveling-wave electroabsorption modulator more precisely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.1
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• pp.89-95
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• 1997

X-cut y-propagation $LiNbO_{3}$ optical modulator is analyzed by finite element calculation. the purpose of this trial is the design of wide-bandwidth x-cut $LiNbO_{3}$ optical modulator with ridge wave guide, which was only applied to z-cut $LiNbO_{3}$ optical modulator. the simulation tool is examined by the comparison between our results and Becker's. And we consider the optimum position of optical waveguide to electrodes for decreasing the driving voltage. The calculated driving-voltage, characteristic impedance and microwave effective index at $1.3{\mu}{\textrm{m}}$ optical wavelength are 18 V.cm, $48.13{\Omega}$ and 2.168, respectively.