Dielectric laser acceleration of sub-100 keV electrons with silicon dual-pillar grating structures

Abstract

We present the demonstration of high-gradient laser acceleration and deflection of electrons with silicon dual-pillar grating structures using both evanescent inverse Smith-Purcell modes and coupled modes. Our devices accelerate subrelativistic 86.5 and 96.3 keV electrons by 2.05 keV over 5.6 μm distance for accelerating gradients of 370 MeV/m with a 3 nJ mode-locked Ti:sapphire laser. We also show that dual pillars can produce uniform accelerating gradients with a coupled-mode field profile. These results represent a significant step toward making practical dielectric laser accelerators for ultrafast, medical, and high-energy applications.

Method for computationally efficient design of dielectric laser accelerator structures

“…Furthermore, the structures that we design are fabricable. Although no DLA structures have been tested at the proposed wavelength of 2 µm, both simulations [2] and experimental results from other wavelengths [5] show gradients far below those presented here. We had limited success designing DLA structures in the relativistic (β ≈ 1) regime, especially for higher index materials, such as Si.…”

“…Several recently demonstrated candidate DLA structures consist of a planar dielectric structure that is periodic along the particle axis with either an semi-open geometry or a narrow (micron to sub-micron) vacuum gap in which the particles travel [2][3][4][5][6][7][8][9]. These structures are then sideilluminated by laser pulses.…”

“…In previous works, candidate DLA geometries were optimized for maximum acceleration gradient by scanning through parameters of a specified structure geometry [2][3][4][5][6][7][8][9]. However, this strategy has limited potential to produce higher acceleration gradient structures because it only searches a small portion of the total design space.…”

Beam quality study for a grating-based dielectric laser-driven accelerator

“…So far, two experiments have successfully demonstrated high accelerating gradients of 300 MV/m 15 and 690 MV/m 16 for relativistic electron acceleration in fused silica dual-grating structures. As for non-relativistic electron acceleration, accelerating gradients of 25 MV/m 17 for fused silica, and 220 MV/m 18 and 370 MV/m 19 for silicon structures have previously been observed.…”

Summary report of working group 3: Laser and high-gradient structure-based acceleration

“…A. Ceballos of Stanford University presented data from such gratings-based structures and a new structure based on silicon dual pillars [6]. The dual pillars can be tuned to shape and optimize the accelerating field profiles.…”