Dielectric laser accelerators

Abstract

The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. We review the physics and technology of this approach, which we refer to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV/m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Due to the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

Conceptual and Technical Design Aspects of Accelerators for External Injection in LWFA

“…In Dielectric Laser Acceleration (DLA) µJ laser pulses with wavelength in the µm scale are coupled (typically perpendicularly) to a micro-structure made from a dielectric material such as SiO 2 or Si [8]. Due to the short length of the acceleration channel in the longitudinal direction, compared to the typical electron bunch length in linear accelerators, only energy modulation experiments have been realized so far, proving an energy gain of part of the electrons in the bunch of the order of tens of keV [9].…”

Isolated few-cycle radiation from chirped-pulse compression of a superradiant free-electron laser

“…A laser wakefield accelerator [7] has been proven useful to generate 10-50 fs electron bunches. It is envisaged that a future dielectric laser accelerator (DLA) [8], directly driven by a laser field, is to generate electron bunches in the attosecond time scale. It is well known that, when a radiating electron bunch is significantly shorter than the radiation wavelength, all the electrons radiate coherently with total radiation spectral energy proportional to the square of the charge in the electron bunch.…”

Towards graphene plasmon-based free-electron infrared to X-ray sources

“…These qualities, coupled with the high confinement factors -and hence small spatial periodicity -of GPs, make graphene a promising platform upon which to realize chip-scale light sources with low-energy electrons, circumventing the use of additional acceleration stages. Interestingly, recent work has already demonstrated large gradient on-chip acceleration [35,45,46], which if successfully scaled up, could create highly-compact few-MeV accelerators, thus making even the hard X-ray graphene-based source accessible on chip. The GP-based free-electron radiation source offers a rich field for further exploration.…”

“…Graphene is especially suited to our purpose due to its combination of metallic and dielectric properties: it can support electric fields stronger than any metal and even comparable to those supported by dielectric structures [22,35], while its high conductivity prevents charge accumulation that might otherwise hinder its usability. For example, the peak electric field amplitude of 3 GV/m on the graphene assumed in 2(a) is below the graphene breakdown threshold [36].…”

“…The prospect of a GP-based freeelectron laser -in which the radiation output causes the electrons to bunch coherently via selfamplified spontaneous emission [20,35,47] -is also an interesting topic of future research. In general, electrons can also excite plasmons [48,49], which might back-react on them and influence both the radiation emission and the plasmon emission.…”