Near-Complete Absorption of Intense, Ultrashort Laser Light by Sub-λGratings

Abstract

We demonstrate near-100% light absorption and increased x-ray emission from dense plasmas created on solid surfaces with a periodic sub-lambda structure. The efficacy of the structure-induced surface plasmon resonance, responsible for enhanced absorption, is directly tested at the highest intensities to date (3 x 10{15} W cm{-2}) via systematic, correlated measurements of absorption and x-ray emission. An analytical grating model as well as 2D particle-in-cell simulations conclusively explain our observations. Our study offers a definite, quantitative way forward for optimizing and understanding the absorption process.

Enhanced surface acceleration of fast electrons by using subwavelength grating targets

“…Targets with sub-wavelength structured surface such as foam, porous, nanometer-scale particles, clusters, nano-wires [21] have shown efficient enhancement of laser absorption and fast electron generation. Sub-wavelength grating targets, as the simplest material with structured surface of sub-wavelength (one dimension), also possesses near-complete laser absorption and enhanced x-ray emission induced by fast electrons [27]. Surface acceleration of fast electrons may prospectively be enhanced by using the targets with sub-wavelength structured surface.…”

“…4(b). Because the incident angle of laser beam departs far from the resonant angle, the improved laser absorption and fast electrons generation by using grating target should not be induced by surface plasmon resonance excitation [24][25][26][27][28].…”

Efficient ion generation in laser-foil interaction

“…At the target rear side the additional wider holes are installed to ensure the proton beam collimation based on our previous study [13] throughout the paper. Thin foil tailored targets, which have a subwavelength structure, enhance the laser energy absorption [21][22][23][24].…”

“…The subwavelength-multiholes transpiercing the planar target enhance the laser-proton energy conversion efficiency [21][22][23]. The subwavelength microstructured targets [21][22][23][24][25] are propitious to enhance the laser energy absorption. In this paper a e-mail: kwt@cc.utsunomiya-u.ac.jp This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.…”

“…The energy of ions, which are accelerated in an interaction between an intense laser pulse and a thin foil target, has been over MeV [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The ion acceleration in the laser-foil interaction is expected to be a new method of ion acceleration.…”