Prof. Peter Hommelhof: "Nanophotonics-based particle acceleration"
It is well known for decades that light can impart momentum to charged particles in the vicinity of a third body. With nanostructured dielectric materials and ultrafast laser pulses, this momentum transfer can become highly efficient, demonstrated in 2013 in two proof-of-concept experiments. Since then, not only acceleration has been shown but also deflection and focusing based purely on optical nearfield forces. With these ingredients at hand, we are now at a point to build an on-chip particle accelerator. Like in any accelerator, active beam confinement is as important as acceleration, in order not to lose particles while they are accelerated. For this, the alternating phase focusing scheme is employed in RF accelerators to keep an electron pulse well contained while it is accelerated. Alternating phase focusing relies on excellent electron phase space control, which is what we have achieved, at optical frequencies an in the 400-nm wide channel of an 80 micrometer long nanophotonic structure. In this talk, I will show the status of nanophotonics-based particle acceleration, including an outlook on applications of the particle accelerator on a chip, which is now within close reach. This work is funded by the Gordon and Betty Moore Foundation (Accelerator on a Chip International Program - ACHIP), ERC Advanced Grant AccelOnChip and BMBF.