Abstract-Nonlinear Transfer of Intense Few Cycle Terahertz Pulse Through Opaque n-doped Si

O. V. Chefonov, A. V. Ovchinnikov, M. B. Agranat, V. E. Fortov, E. S. Efimenko, A. N. Stepanov, A. B. Save'lev

https://arxiv.org/abs/1805.09611

Intense few cycle terahertz pulses exhibit complex non-linear behavior under interaction with heavily n-doped Si. Fast increase in the transmission of a 700 fs pulse (central frequency 1.5 THz) through the Si sample (low field transmission of 0:02 %) saturates at 8 % for the external field of 5 MV/cm and then drops twofold at 20 MV/cm. An electro-optical sampling measurements revealed formation of a single cycle terahertz pulse at this field due to formation of a thin ionized layer by the first intense oscillation of the terahertz field.

Abstract-Damage in a Thin Metal Film by High-Power Terahertz Radiation

M. B. Agranat, O. V. Chefonov, A. V. Ovchinnikov, S. I. Ashitkov, V. E. Fortov, and P. S. Kondratenko

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.085704

We report on the experimental observation of high-power terahertz-radiation-induced damage in a thin aluminum film with a thickness less than a terahertz skin depth. Damage in a thin metal film produced by a single terahertz pulse is observed for the first time. The damage mechanism induced by a single terahertz pulse could be attributed to thermal expansion of the film causing debonding of the film from the substrate, film cracking, and ablation. The damage pattern induced by multiple terahertz pulses at fluences below the damage threshold is quite different from that observed in single-pulse experiments. The observed damage pattern resembles an array of microcracks elongated perpendicular to the in-plane field direction. A mechanism related to microcracks’ generation and based on a new phenomenon of electrostriction in thin metal films is proposed.

• 
• 
• 
• 

Abstract-Generation of 0.9-mJ THz pulses in DSTMS pumped by a Cr:Mg2SiO4 laser

C. Vicario, A. V. Ovchinnikov, S. I. Ashitkov, M. B. Agranat, V. E. Fortov, and C. P. Hauri  »View Author Affiliations

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-23-6632

Optics Letters, Vol. 39, Issue 23, pp. 6632-6635 (2014)
http://dx.doi.org/10.1364/OL.39.006632

We report on high-field terahertz transients with 0.9-mJ pulse energy produced in a 400  mm2 partitioned organic crystal by optical rectification of a 30-mJ laser pulse centered at 1.25 μm wavelength. The phase-locked single-cycle terahertz pulses cover the hard-to-access low-frequency range between 0.1 and 5 THz and carry peak fields of more than 42 MV/cm and 14 Tesla with the potential to reach over 80 MV/cm by choosing appropriate focusing optics. The scheme based on a Cr:Mg2SiO4 laser offers a high conversion efficiency of 3% using uncooled organic crystal. The collimated pump laser configuration provides excellent terahertz focusing conditions.

© 2014 Optical Society of America