Strong-field physics with mid-infrared lasers

摘要

Mid-infrared gas laser technology promises to become a unique tool for research in strong-field relativistic physics. The degree to which physics is relativistic is determined by a ponderomotive potential. At a given intensity, a 10 μm wavelength CO{sub}2 laser reaches a 100 times higher ponderomotive potential than the 1 μm wavelength solid state lasers. Thus we can expect a proportional increase in the throughput of such processes as laser acceleration, N-ray production, etc. These arguments have been confirmed its proof-of-principle Thomson scattering and laser acceleration experiments conducted at BNL and UCLA where the first terawatt-class CO{sub}2 lasers are in operation. Further more, proposals for the 100 TW, 100 fs CO{sub}2 lasers based on frequency-chirped pulse amplification have been conceived. Such lasers can produce physical effects equivalent to a hypothetical multi-petawatt solid state laser. Ultrafast mid-infrared lasers will open new routes to the next generation electron and ion accelerators, ultra-bright monochromatic femtosecond x-ray and gamma sources, allow to attempt the study of Hawking-Unruh radiation, and explore relativistic aspects of laser-matter interactions. We review the present status and experiments with terawatt-class CO{sub}2 lasers, sub-petawatt projects, and prospective applications in strong-field science.