Image credit: Credit: ORNL.gov

　　Researchers at the University of Strathclyde are developing groundbreaking plasma based light amplifiers that could replace traditional high power laser amplifiers.

　　The research group at the Glasgow-based University are leading efforts to take advantage of plasma, the ubiquitous medium that makes up most of the universe, to make the significant scientific breakthrough.

　　The next generation of high power lasers should be able to crack the vacuum to produce real particles from the sea of virtual particles. Example of these types of lasers can be found at the Extreme Light Infrastructure in Bucharest, Prague and Szeged, which are pushing the boundaries of what can be done with high intensity light.

　　Professor Dino Jaroszynski and Dr Gregory Vieux from Strathclyde's Faculty of Science hope that the developments can produce a very compact and robust light amplifier.

　　Professor Jaroszynski said: "The lasers currently being used are huge and expensive devices, requiring optical elements that can be more than a metre in diameter. Large laser beams are required because traditional optical materials are easily damaged by high intensity laser beams.

　　"Plasma is completely broken down atoms, which are separated into their constituent parts of positively charged ions and very light and mobile electrons, which have unique properties in that they respond easily to laser fields.

　　"We are investigating the limitations of this method of amplifying short laser pulses in plasma and hope this will lead to a more compact and cost effective solution."

　　The research was published in Scientific Reports by the publishers of Nature, through a paper entitled "Chirped pulse Raman amplification in warm plasma: towards controlling saturation". It suggests that electron trapping and wavebreaking are the main physical processes limiting energy transfer efficiency in plasma-based amplifiers.

　　The authors have demonstrated that pump chirp (chirping similar to that of a Swanni or slide whistle) and finite plasma temperature reduce the amplification factor. Moreover, the electron thermal distribution (the way the particle velocities are distributed) leads to particle trapping (particles get stuck in troughs of the waves) and a nonlinear frequency shift (the colour of the amplified lights changes), which further reduces amplification. The team also suggest methods for achieving higher efficiencies.

　　Explore further: The art of amplification: A desktop-size 10 terawatt laser

　　More information: "Chirped pulse Raman amplification in warm plasma: towards controlling saturation" Scientific Reports 5, Article number: 13333 (2015). DOI: 10.1038/srep13333

　　Journal reference: Scientific Reports

转载自：http://www.sic.ac.cn/xwzx/kjxx/201508/t20150824_4414182.html