Contrasting levels of absorption of intense femtosecond laser pulses by solids
Singh, Prashant Kumar and Cui, Y. Q. and Adak, Amitava and Lad, Amit D. and Chatterjee, Gourab and Brijesh, P. and Sheng, Z. M. and Kumar, G. Ravindra (2015) Contrasting levels of absorption of intense femtosecond laser pulses by solids. Scientific Reports, 5. 17870. ISSN 2045-2322 (https://doi.org/10.1038/srep17870)
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Abstract
The absorption of ultraintense, femtosecond laser pulses by a solid unleashes relativistic electrons, thereby creating a regime of relativistic optics. This has enabled exciting applications of relativistic particle beams and coherent X-ray radiation, and fundamental leaps in high energy density science and laboratory astrophysics. Obviously, central to these possibilities lies the basic problem of understanding and if possible, manipulating laser absorption. Surprisingly, the absorption of intense light largely remains an open question, despite the extensive variations in target and laser pulse structures. Moreover, there are only few experimental measurements of laser absorption carried out under very limited parameter ranges. Here we present an extensive investigation of absorption of intense 30 femtosecond laser pulses by solid metal targets. The study, performed under varying laser intensity and contrast ratio over four orders of magnitude, reveals a significant and non-intuitive dependence on these parameters. For contrast ratio of 10-9 and intensity of 2 × 1019W cm-2, three observations are revealed: preferential acceleration of electrons along the laser axis, a ponderomotive scaling of electron temperature, and red shifting of emitted second-harmonic. These point towards the role of J × B absorption mechanism at relativistic intensity. The experimental results are supported by particle-in-cell simulations.
ORCID iDs
Singh, Prashant Kumar, Cui, Y. Q., Adak, Amitava, Lad, Amit D., Chatterjee, Gourab, Brijesh, P., Sheng, Z. M. ORCID: https://orcid.org/0000-0002-8823-9993 and Kumar, G. Ravindra;-
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Item type: Article ID code: 55224 Dates: DateEvent9 December 2015Published5 November 2015AcceptedSubjects: Science > Physics > Optics. Light Department: UNSPECIFIED Depositing user: Pure Administrator Date deposited: 05 Jan 2016 14:05 Last modified: 04 Oct 2024 00:23 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/55224