Abstract-Experimental Estimate of the Nonlinear Refractive Index of Crystalline ZnSe in the Terahertz Spectral Range

A. N. Tcypkin, S. E. Putilin, M. C. Kulya, M. V. Melnik, A. A. Drozdov, V. G. Bespalov, X.-C. Zhang, R. W. Boyd, S. A. Kozlov

https://link.springer.com/article/10.3103%2FS1062873818120237


A modification of the Z-scan technique for measuring nonlinear refractive index n2 in the terahertz spectral region is proposed. Measurements are made at a broadband terahertz radiation intensity of 0.8 × 109 W cm−2. Coefficient n2 = 2.5 × 10−11 cm2 W−1 is estimated for semiconductor crystalline ZnSe.

Abstract-Concentration dependence of terahertz generation in jets of water and ethanol mixtures

A. N. Tcypkin, E. A Ponomareva, S. E. Putilin, S. V. Smirnov, S. A. Shtumpf, M. V. Melnik, Y. E, S. A. Kozlov, X.-C. Zhang,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10826/1082603/Concentration-dependence-of-terahertz-generation-in-jets-of-water-and/10.1117/12.2501217.short

In this work, we considered mixtures of ethanol and water in the form of jets as samples for THz generation based on laser-induced filamentation. The dependence of the output energy of terahertz radiation on the concentration of ethanol in water was experimentally studied. It is shown that the energy grows linearly, which can be explained by an increase in the ionization energy due to the linear replacement of low-efficient charge carriers (water) with highly-efficient (ethanol). The dependence of the THz generation on the optical angle of incidence on the mixture jets was also demonstrated. The results of this study can be further used to create universal source of terahertz radiation.

© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Glycerol dehydration of native and diabetic animal tissues studied by THz-TDS and NMR methods

O. A. Smolyanskaya, I. J. Schelkanova, M. S. Kulya, E. L. Odlyanitskiy, I. S. Goryachev, A. N. Tcypkin, Ya. V. Grachev, Ya. G. Toropova, and V. V. Tuchin

https://www.osapublishing.org/boe/abstract.cfm?uri=boe-9-3-1198&origin=search

The optical clearing method has been widely used for different spectral ranges where it provides tissue transparency. In this work, we observed the enhanced penetration of the terahertz waves inside biological samples (skin, kidney, and cornea) treated with glycerol solutions inducing changes of optical and dielectric properties. It was supported by the observed trend of free-to-bound water ratio measured by the nuclear magnetic resonance (NMR) method. The terahertz clearing efficiency was found to be less for diabetic samples than for normal ones. Results of the numerical simulation proved that pulse deformation is due to bigger penetration depth caused by the reduction of absorption and refraction at optical clearing.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Measurement of the nonlinear refractive index in ZnSe crystal by modified methodof Z-scan in the terahertz spectral range

 A. N. Tcypkin,  S. E. Putilin,   M. S. Kulya,  M. Siddiqui, S. Choudhary,  J. Zhao,   V. G. Bespalov, R.W. Boyd,   X. C. Zhang,  S. A. Kozlov

http://ieeexplore.ieee.org/document/8066912/

We report the measurement of the intensity-dependent refractive index m of ZnSe crystal at THz frequencies. We used a modified Z-scan method with an intense THz beam of maximum intensity 0.8×109W/cm2. We measured an extremely large m value of the order of 10−11 cm2/W, which is significantly larger than the m value of ZnSe in the near infrared.