• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.169-173
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• 2016

Terahertz (THz) generation by a GaP ridge waveguide with a collinear modal phase-matching scheme based on cascaded difference frequency generation (DFG) processes is theoretically analyzed. The cascaded Stokes interaction processes and the cascaded anti-Stokes interaction processes are investigated from coupled wave equations. THz intensities and quantum conversion efficiency are calculated. Compared with non-cascaded DFG processes, THz intensities from 11-order cascaded DFG processes are increased to 5.48. The quantum conversion efficiency of 177.9% in cascaded processes can be realized, exceeding the Manley-Rowe limit.

• Current Optics and Photonics
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• v.1 no.2
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• pp.138-142
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• 2017

Terahertz (THz) generation by periodically-poled $KTiOPO_4$ (PPKTP) with a quasi-phase-matching scheme based on cascaded difference frequency generation (DFG) processes is theoretically analyzed. The cascaded Stokes interaction processes and the cascaded anti-Stokes interaction processes are investigated from coupled wave equations. THz intensities and quantum conversion efficiency are calculated. Compared with non-cascaded DFG processes, THz intensities from 10-order cascaded DFG processes are increased to 5.53. The quantum conversion efficiency of 479.4% in cascaded processes, which exceeds the Manley-Rowe limit, can be realized.

• Current Optics and Photonics
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• v.2 no.2
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• pp.179-184
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• 2018

Terahertz (THz) wave generation by periodically poled $BaTiO_3$ (PPBT) with a quasi-phase-matching (QPM) scheme based on cascaded difference-frequency generation (DFG) is theoretically analyzed. The cascaded DFG processes comprise cascaded Stokes and anti-Stokes processes. The calculated results indicate that the cascaded Stokes processes are stronger than the cascaded anti-Stokes processes. Compared to a noncascaded Stokes process, THz intensities from $20^{th}$-order cascaded Stokes processes increase by a factor of 30. THz waves with a maximum intensity of $0.37MW/mm^2$ can be generated by $20^{th}$-order cascaded DFG processes when the optical intensity is $10MW/mm^2$, corresponding to a quantum conversion efficiency of 1033%. The high quantum conversion efficiency of 1033% exceeds the Manley-Rowe limit, which indicates that PPBT is an excellent crystal for THz wave generation via cascaded DFG.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.156-157
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• 2003

The wavelength converter is considered to be a key element of future dense WDM optical networks. It enables wavelength reuse and resolves contention problem. Moreover, the tunability of the wavelength converter enhance the flexibility of network systems by facilitating reconfigurable dynamic wavelength routing. In order to achieve optically tunable wavelength conversion, we recently proposed and experimentally demonstrated wavelength conversion and tuning based on cascaded sum and difference frequency generation in a Ti：PPLN channel waveguide. (omitted)