Swallowing laser light
doi:10.1038/nindia.2008.305 Published online 22 October 2008
Researchers have been able to achieve near complete absorption of ultra-short laser pulses on gold-coated glass surfaces1. The study results will have fascinating applications in particle acceleration and medical therapies.
The researchers devised two modified glass targets – gold-coated grating target and gold-coated smooth target. They shot ultra-short laser pulses (lasting for tens of a millionth of a billionth of a second) on the targets. The absorbed light generated hot electrons in the plasma, which gave rise to hard x-rays.
The study results promise a very attractive opportunity for tuning the absorption and controlling the flux and energies of hot electrons and x-rays from laser-produced solid plasmas. One can tune the hot electron temperature by switching the polarization state of the light and choosing the angle of incidence very precisely.
"We see almost complete absorption of light," says lead researcher G. Ravindra Kumar. The study provides direct evidence that surface plasmons (collective oscillation of the free electron gas density on the surface) enable efficient coupling of light and plasmas at intensities prevalent in intense laser-solid interaction studies, he adds.
The authors of this work from: Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai, India; Institute for Plasma Research, Bhat, Gandhinagar, India; Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing, China and Department of Physics, Shanghai Jiao Tong University, Shanghai, China.
- Kahaly, S. et al. Near-Complete Absorption of Intense, Ultrashort Laser Light by Sub-l Gratings. Phys. Rev. Lett. 101, 145001 (2008) | Article |