Optica Open
arXiv.svg (5.58 kB)

Boosting the efficiency of Smith-Purcell radiators using nanophotonic inverse design

Download (5.58 kB)
posted on 2023-01-12, 14:02 authored by Urs Haeusler, Michael Seidling, Peyman Yousefi, Peter Hommelhoff
The generation of radiation from free electrons passing a grating, known as Smith-Purcell radiation, finds various applications including non-destructive beam diagnostics and tunable light sources, ranging from terahertz towards X-rays. So far, the gratings used for this purpose have been designed manually, based on human intuition and simple geometric shapes. Here we apply the computer-based technique of nanophotonic inverse design to build a 1400nm Smith-Purcell radiator for sub-relativistic 30 keV electrons. We demonstrate that the resulting silicon nanostructure radiates with a 3-times-higher efficiency and 2.2-times-higher overall power than previously used rectangular gratings. With better fabrication accuracy and for the same electron-structure distance, simulations suggest a superiority by a factor of 96 in peak efficiency. While increasing the efficiency is a key step needed for practical applications of free-electron radiators, inverse design also allows to shape the spectral and spatial emission in ways inaccessible with the human mind.



This arXiv metadata record was not reviewed or approved by, nor does it necessarily express or reflect the policies or opinions of, arXiv.

Usage metrics