Speaker
Description
Dielectric laser acceleration (DLA) applies well-known concepts of structure-based accelerators at a microscopic length scale by driving dielectric structures with strong infrared femtosecond laser pulses [1]. In DLA, the optical electro-magnetic fields take the role of the microwave fields, and the transparent dielectric structures shape the field, similar to the microwave structures in RF accelerators.
Utilizing the high damage threshold of dielectric materials at optical frequencies as compared to metallic radiofrequency cavities, it has been shown that DLAs can achieve acceleration gradients an order of magnitude larger than conventional accelerators. For relativistic energies, acceleration gradients of up to 1.8 GeV/m have been demonstrated [2], while gradients of 370 MeV/m were reached at sub-relativistic energies [3]. New material and laser pulse combinations could allow going up to 10 GV/m field strengths, further increasing the possible gradients.
In extended DLA structures and in multi-stage setups, the beam guiding inside the narrow structures plays a major role. This can be achieved by employing alternating phase focusing (APF), a scheme also adopted from microwave accelerators. While proposed for DLA in [4] and experimentally shown in [5] for guiding without energy gain, we were recently able to combine acceleration and guiding in [6], where we accelerated electrons from 28.4 to 40.7 keV in a 500 µm long structure.
While this only corresponds to a modest acceleration gradient of 22.7 MeV/m, comparable to that of microwave accelerators, this marks a breakthrough as a proof of concept for DLA technology and a good starting point for future optimization. While an application in linear colliders at multi-TeV seems possible [7], other applications in industry, science and especially medicine seem to be within closer reach. We will also show entirely new applications of electron-light coupling at dielectric nanostructures taking advantage of the quantum-coherent nature of the coupling [8].
[1] England, R. J. et al. Dielectric laser accelerators. Rev. Mod. Phys. 86, 1337 (2014)
[2] Cesar, D., Custodio, S., Maxson, J., Shen, X., Threlkeld, E., England, R. J., Hanuka, A., Makasyuk, I. V., Peralta, E. A., Wootton, K. P. and Wu, Z. High-field nonlinear optical response and phase control in a dielectric laser accelerator. Commun. Phys. 1, 46 (2018).
[3] Leedle, K. J., Ceballos, A., Deng, H., Solgaard, O., Pease, R. F., Byer, R. L. and Harris, J. S. Dielectric laser acceleration of sub-100 keV electrons with silicon dual-pillar grating structures. Opt. Lett. 40, 4344-4347 (2015)
[4] Niedermayer, U., Egenolf, T., Boine-Frankenheim, O. and Hommelhoff, P. Alternating-Phase Focusing for Dielectric-Laser Acceleration. Phys. Rev. Lett. 121, 214801 (2018)
[5] Shiloh, R., Illmer, J., Chlouba, T., Yousefi, P., Schönenberger, N., Niedermayer, U., Mittelbach, A. and Hommelhoff, P. Electron phase-space control in photonic chip-based particle acceleration. Nature 597, 498–502 (2021)
[6] Chlouba, T., Shiloh, R., Kraus, S., Brückner, L., Litzel, J. and Hommelhoff, P. Coherent nanophotonic electron accelerator. Nature 622, 476–480 (2023)
[7] Shiltsev, V. and Zimmermann, F. Modern and future colliders. Rev. Mod. Phys. 93, 015006 (2021)
[8] García de Abajo, F. J. et al. Roadmap for Quantum Nanophotonics with Free Electrons. ACS Photonics (2025)
