Abstract

Femtosecond mid-IR lasers in the 3—8 µm wavelength range hold great promise for numerous research areas in atomic, molecular and optical physics. There are several broad application scopes for each of the currently achievable pulse energy and repetition rate ranges. Microjoule-level sources are required for 2D mid-IR spectroscopy permitting access to ultrafast structural dynamics of molecules through bond-specific vibrational coupling. (Sub-)millijoule mid-IR pulses are required in strong-field molecular techniques to prevent premature photo-dissociation of large molecules and facilitate bond-selective photoionization. Multimillijoule mid-IR drivers, as a consequence of a λ² scaling of the ponderomotive energy, are critical in the generation of coherent [1] and incoherent [2] secondary radiation in the X-ray and THz domains [3]. Such high-energy driver pulses are also proving indispensable in femtosecond filamentation [4] because of the unique opportunity to initiate plasma-chemical reactions with hot electrons emitted through long-wave optical field ionization. Further scaling of such longwave few-cycle sources, eventually into the relativistic regime, would make it possible to exploit the wavelength scaling advantage for particle acceleration and enable replacement of single-shot dense targets by indestructible high-pressure gas targets.

© 2015 IEEE