An international study proposing that a massive fiber laser system could produce the next-generation particle accelerator has now been published. In February, scientists from the Optoelectronics Research Centre (ORC) at the University of Southampton announced they were teaming with three international research labs — École Polytechnique of Paris, the Fraunhofer Institute for Applied Optics and Precision Engineering, and CERN — under the International Coherent Amplification Network (ICAN) to investigate the use of fiber lasers as an energy source for high-energy particle accelerators such as the Large Hadron Collider (LHC). (See: Using Fiber Lasers for Particle Acceleration Technologies). Phasing the lasers to within a fraction of a wavelength previously seemed insurmountable, but “preliminary proof of concept suggests that thousands of fibers can be controlled to provide a laser output powerful enough to accelerate electrons to energies of several GeV at 10-kHz repetition rate — an improvement of at least ten thousand times over today’s state-of-the-art lasers,” said the ORC’s Dr. Bill Brocklesby, an ICAN member. “A typical CAN [coherent amplification network] laser for high-energy physics may use thousands of fibers, each carrying a small amount of laser energy. It offers the advantage of relying on well-tested telecommunication elements, such as fiber lasers and other components. The fiber laser offers an excellent efficiency due to laser diode pumping. It also provides a much larger surface cooling area and, therefore, makes possible high-repetition-rate operation,” he added. Lasers can provide petawatts of energy in femtoseconds, important for applied tasks in medicine or the environment, but two major hurdles prevent them from becoming a viable and widely used technology: an operation rate of only one laser pulse per second and an notorious inefficiency, which often produce output powers that are a fraction of a percent of the input power. A fiber drawing tower at the University of Southampton’s Optoelectronics Research Centre. Courtesy of the University of Southampton. To bridge this divide, the ICAN consortium — a European Union-funded project that includes 12 other laboratories from around the world — aims to harness the fiber lasers’ efficiency, controllability and high average power. Their plan is to replace the conventional laser’s single monolithic rod amplifier with a network of thousands of fiber amplifiers and telecommunication components. The laser system could be used for both fundamental research and more applied tasks, such as proton therapy and nuclear transmutation. Such a combined fiber laser system should provide the necessary power and efficiency that could make economical the production of a large flux of relativistic protons over millimeter lengths as opposed to a few hundred meters. One important application demonstrated, said Gérard Mourou of École Polytechnique, who leads the consortium, is “the possibility to accelerate particles to high energy over very short distances measured in centimeters rather than kilometers, as it is the case today with conventional technology. This feature is of paramount importance when we know that today high-energy physics is limited by the prohibitive size of accelerators, of the size of tens of kilometers, and costs billions of euros. Reducing the size and cost by a large amount is of critical importance for the future of high energy physics.” The results appeared in Nature Photonics (doi: 10.1038/nphoton.2013.75). For more information, visit: www.southampton.ac.uk