The acceleration of electrons using high-energy ultrafast laser pulses has a long history, but developments in lasers over the last ten years have brought the production of laser-based particle accelerators closer to reality. Impressive electron acceleration has already been demonstrated, but present high-energy ultrafast lasers have low repetition rates, so that electron bunches could only be accelerated at the rate of a few per second. The ICAN project aims to address the challenge of producing high energy ultrafast pulses at very high rates, to match the high pulse repetition rates of RF accelerators.
In order to get electron acceleration of, for example, 10 GeV in an accelerator stage, laser pulse energies of order 10 J are necessary, and a repetition rate of 10kHz implies an average laser power of 100 kW. This level of average power is difficult to achieve, but one laser technology proven to be well suited to high average power applications is the fibre laser. Fibre lases with average powers in the tens to hundreds of kW are commercially available. One major advantage of fibre lasers is that they can be extremely efficient, with wallplug efficiencies of order 50%. Ultrafast pulse fibre lasers, however, can produce only lower energy pulses because of optical nonlinearities in the fibre medium.
The ICAN project aims to harness the efficiency, controllability, and high power capability of fibre lasers to produce high energy, high repetition rate pulse sources. This will be achieved by coherent addition of the pulses from thousands of lasers, leveraging the control and mass production capabilities developed by the fibre laser community in the telecoms area. Experts from the fields of high average power fibre lasers, high pulse energy fibre lasers, and beam combination technologies are working in a consortium, together with industries involved with component mass production and high volume packaging to explore the concept of a laser system which could provide the tens of Joules energy at rates above 1 kHz by coherently combining the output of thousands of pulsed fibre lasers.