• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.175-180
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• 2006

A single sideband(SSB) modulator operating at 5.5 GHz was fabricated by polarization inversion techniques. The dimension of domain inversion in a $LiINbO_3$ Mach-Zehnder structure was precisely controlled so that the RF signal applied on two Mach-Zehnder arms gives rise to $90^{\circ}$ effective phase difference. The single sideband suppression was maximized by optimization of the polarization status of the optical input and by the DC bias value. The fabricated device showed the center frequency of 5.8 GHz and the maximum sideband suppression of 33dB, where the bandwidth of 15 dB sideband suppression ranged over a 2.5 GHz span. The optical phase delay could be regulated by the DC bias voltage, fur example, the enhanced optical modulation sideband was distinctively switched from the upper sideband to the lower sideband by changing the DC bias voltage from 1.9 V to -10.6 V.

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.181-182
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• 2006

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.20-25
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• 2007

The periodic domain-inversion in the selective areas of $Ti:LiNbO_3$ Mach-Zender waveguides was performed and band-pass modulators and single sideband (SSB) modulators were fabricated by using domain-reversal. The domain wall velocity was precisely controlled by real-time analysis of a poling-induced response current under an applied voltage. The domain wall velocity was significantly affected by the crystal orientation of the domain wall propagation which influenced the final domain geometry. In a certain case, the decomposition of $LiNbO_3$ crystal was observed, for example, under the condition of too fast domain wall propagation. The fabricated band-pass modulator with a periodic domain-inversion structure showed the maximum modulation efficiency at 30.3 GHz with 5.1 GHz 3dB-bandwidth, and SSB modulator was measured to show 33 dB USB suppression over LSB at 5.8 GHz RF.