As pulses are amplified in Vulcan the width of the frequency spread of the pulse is reduced, this process is called gain narrowing.
Gain narrowing acts as a limit to the shortest pulse that we can achieve from the laser. To achieve short pulse durations for the Petawatt target area we have to use amplifiers that maintain the required frequency spread. This is achieved by pre-amplifying the pulses from the nano-joule to milli-joule levels in the OPCPA pre-amplifier.
OPCPA stands for Optical Parametric Chirped Pulse Amplification and means that we use optical parametric amplification to amplify a chirped pulse. Optical parametric amplification is a process that occurs in non-linear crystals when an intense pump beam is used to amplify a weaker signal beam.
