Characteristics of quasi-unipolar electromagnetic pulses formed in the interaction of high-power laser pulses with nanoscale targets

• Published in: Quantum electronics (Woodbury, N.Y.) N.Y.), 2019-08, Vol.49 (8), p.788-795
• Main Authors: Kulagin, V.V., Kornienko, V.N., Cherepenin, V.A., Gupta, D.N., Suk, H.
• Format: Article
• Language: English
• Subjects: Acceleration; Amplitudes; BEAMS; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Computer simulation; COMPUTERIZED SIMULATION; ELECTROMAGNETIC PULSES; Electromagnetic radiation; electron acceleration by laser pulses; ELECTRONS; generation of terahertz and IR radiation; High power lasers; interaction of high-power laser pulses with matter; Laser beams; LASER RADIATION; LASERS; nanoscale targets; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; NUMERICAL ANALYSIS; Pulse propagation; REFLECTION; THZ RANGE
• ISSN: 1063-7818; 1468-4799
• DOI: 10.1070/QEL16929

A new method is suggested for generating quasi-unipolar electromagnetic IR and terahertz pulses. The method is based on synchronous acceleration of electrons combined to a dense bunch with a charge of up to several tens nanocoulombs, which are forced out from a nanoscale target under an action of a high-power, sharp-leading edge laser pulse. The electromagnetic bunch moving in a field of laser radiation can generate high-power electromagnetic pulses with various spectral composition including terahertz and IR ranges. A physical mechanism underlying the formation of generated quasi-unipolar pulses of electromagnetic radiation is determined and numerically studied. The pulse characteristics are found by numerical simulation, such as amplitude and duration dependences on the angle between the pulse propagation direction and laser beam axis. It is established that in modern laser installations, the amplitudes of quasi-unipolar pulses may reach relativistic values. Reflection of a unipolar pulse from an ideally reflecting surface is numerically analysed. It is shown that the pulse retains its unipolar profile in this case.