Estimations of Low-Inertia Cubic Nonlinearity Featured by Electro-Optical Crystals in the THz Range

Abstract

Despite the growing interest in nonlinear devices and components for light by light control in the terahertz range, there is a shortage of such materials and media used for these purposes. Here, we present the calculated values of low-inertia nonlinear refractive index coefficient for electro-optical crystals used in THz time-domain spectroscopy systems such as ZnSe, ZnTe, CdTe, GaP, and LiNbO3. The medium parameters affecting the cubic nonlinearity of the vibrational nature increase in the range of 0.5–1 THz have been determined. Comparison of theoretical calculations with known experimental results confirm the theoretical model as well as our analysis of media parameter influence on the cubic nonlinearity. In terms of applications, results obtained open up new perspectives for studying various materials in the THz frequency range.

Radiation shift from triple to quadruple frequency caused by the interaction of terahertz pulses with a nonlinear Kerr medium

“…The value is very close to the measurement result obtained by the authors of cm /W 27 . Note that in work 15 the theoretical estimate of this coefficient was cm /W, which is in good good agreement with our measurement results. The difference in exact value is due to the assumptions and approximations of our theoretical model.…”

“…This can be explained by the fact that in the THz range the value of nonlinear refractive index significantly exceeds the value for the visible and IR frequency ranges 16 . For lithium niobate, this excess is 4 orders of magnitude 15 .…”

Terahertz pump–probe of liquid water at 12.3 THz

“…[16][17][18][19][20][21][22][23][24] Intense THz can be used to perform nonlinear experiments and unveil the transient couplings of the different HB modes. [25][26][27][28][29][30][31][32][33][34] The first results detailing the nonlinear response of water in the THz frequency range are recent, 27,28,32,33,35 and the molecular interpretation is still a matter of ongoing discussion. Tcypkin et al 32,33 performed a series of z-scan measurements at B1 THz on liquid water and associated the third-order nonlinear signal to cascaded second-order anharmonicity of the intramolecular O-H stretching modes.…”

Radiation shift from triple to quadruple frequency caused by the interaction of terahertz pulses with a nonlinear Kerr medium

“…This can be explained by the fact that in the THz range, the value of nonlinear refractive index n 2 significantly exceeds the value for the visible and IR frequency ranges 16 . For lithium niobate, this excess is 4 orders of magnitude 15 .…”

“…Recently, it has been theoretically predicted and experimentally confirmed that the coefficient of the nonlinear refractive index of materials in the terahertz frequency range can be several orders of magnitude higher than its value for the same materials in the visible and near-IR spectral ranges [14][15][16] . This nonlinearity has low-inertia mechanism, which means that high-speed THz photonics devices based on nonlinear effects are promising.…”