Laser systems delivering ultra-fast multi-terawatt high energy pulses are rapidly evolving for use in multidisciplinary applications. Several designs based on optical parametric amplification (OPA) and optical parametric chirped pulse amplification (OPCPA) have been demonstrated , which offer significant potential advantages over standard laser systems. For example, parametric processes support the generation of wide-band signals with limited gain narrowing and  tunable few cycle pulses can be obtained from parametric amplifier for laser-matter interaction experiments. In addition, since OPA does not involve any energy storage mechanism in the gain medium, the amplification is instantaneous, and degradation of the temporal contrast due to fluorescence is confined within the pump pulse duration. Schemes of this kind are crucial for the success of high-intensity experiments on a 100-ps timescale (or more) , since they enhance the temporal contrast outside the 5–20-ps time window of the pulse.

Temporal contrast in OPA

 NH Stuart, D Bigourd, RW Hill, TS Robinson, K Mecseki, S Patankar, GHC New, RA Smith, "Direct fluorescence characterisation of a picosecond seeded optical parametric amplifier', Optics Communications 336, 319 (2015) 

D Bigourd, S Patankar, SI Olsson Robbie, HW Doyle, K Mecseki, N Stuart, K Hadjicosti, N Leblanc, GHC New, RA Smith, " Spectral enhancement in optical parametric amplifiers in the saturated regime " Applied Physics B 113, 627,(2013).

Pump amplifiers for few cycle OPA

K. Mecseki, D. Bigourd, S. Patankar, N. H Stuart, R. A Smith, "Flat-top ps pulses generated by chirped spectral modulation from a Nd:YLF regenerative amplifier for pumping few-cycle optical parametric amplifiers" Applied Optics, 53, 2229 (2014)