ABSTRACT
In this chapter, the authors discuss the state of the art of femtosecond optical parametric amplification (OPA) including the most recent developments. The authors briefly review the theory of optical parametric amplification and point out the features relevant to ultrashort pulses, deriving some design criteria. The authors describe another unique feature of OPAs, namely, the capability to generate, under suitable conditions, pulses with a constant carrier-envelope phase. Finally, the authors show how OPAs, thanks to their very high gain and low thermal loading, may provide an alternative route to the generation of ultrahigh peak power pulses, exceeding the PW level. At the OPA output, after the pump has been spectrally filtered, both signal and idler beams are available. In some cases, it is necessary to use a pulse compressor to restore the transform-limited duration of the pulses.
