How it began
In 1992 A. Dubietis, G. Jonušauskas and A. Piskarskas at the Vilnius University Laser Research Center demonstrated what they called a modified chirped pulse amplification technique, in which the laser amplifier was replaced by an optical parametric amplifier. Their paper appeared in the journal Optics Communications. The technique was named optical parametric chirped pulse amplification, or OPCPA, shortly afterward.
Before it existed
Chirped pulse amplification was invented in 1985 by Donna Strickland and Gérard Mourou at the University of Rochester. It solved the long-standing problem that amplifying ultrashort pulses damaged the laser amplifier, and it allowed the energy and power of light pulses to be raised to levels not reached before. The Vilnius work kept the stretching and compressing of pulses from that method but changed the amplifying stage.
How it works
A short pulse is stretched in time, amplified, and then compressed again. In OPCPA the amplification takes place in an optical parametric amplifier pumped by high-energy pulses instead of in a laser medium. Because the parametric process is non-resonant, it offers very high gain, low thermal load, wide freedom in choice of wavelength and a broad amplification bandwidth. The Vilnius group proposed that this would allow femtosecond pulses to be boosted to the terawatt level.
How it spread
OPCPA was quickly seen as a promising way to produce ultrashort pulses with very high peak power. The Central Laser Facility in the United Kingdom states that the 1992 publication laid the groundwork for a technology that let high power lasers pass the 1 petawatt limit. According to Dubietis, it took more than ten years for the potential of compact table-top OPCPA systems to be recognized, and progress has been strongest in the past decade.
Where it stands today
OPCPA and chirped pulse amplification together form the conceptual basis of petawatt laser facilities. Table-top OPCPA systems amplify octave-spanning spectra and produce the shortest pulses in the optical range, with peak powers from several gigawatts to several terawatts. The Vilnius company Light Conversion builds OPCPA systems, including the SYLOS systems made for the ELI-ALPS facility. The technique marked its 30th anniversary in 2022.
