Method for computationally efficient design of dielectric laser accelerator structures
Here, dielectric microstructures have generated much interest in recent years as a means of accelerating charged particles when powered by solid state lasers. The acceleration gradient (or particle energy gain per unit length) is an important figure of merit. To design structures with high acceleration gradients, we explore the adjoint variable method, a highly efficient technique used to compute the sensitivity of an objective with respect to a large number of parameters. With this formalism, the sensitivity of the acceleration gradient of a dielectric structure with respect to its entire spatial permittivity distribution is calculated by the use of only two fullfield electromagnetic simulations, the original and ‘adjoint’. The adjoint simulation corresponds physically to the reciprocal situation of a point charge moving through the accelerator gap and radiating. Using this formalism, we perform numerical optimizations aimed at maximizing acceleration gradients, which generate fabricable structures of greatly improved performance in comparison to previously examined geometries.
 Authors:

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 Stanford Univ., Stanford, CA (United States)
 Louisiana State Univ., Baton Rouge, LA (United States)
 SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Publication Date:
 Grant/Contract Number:
 GBMF4744; 1254934; AC0276SF00515
 Type:
 Accepted Manuscript
 Journal Name:
 Optics Express
 Additional Journal Information:
 Journal Volume: 25; Journal Issue: 13; Journal ID: ISSN 10944087
 Publisher:
 Optical Society of America (OSA)
 Research Org:
 SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 43 PARTICLE ACCELERATORS; optical devices; gratings; subwavelength structures
 OSTI Identifier:
 1369313
Hughes, Tyler, Veronis, Georgios, Wootton, Kent P., England, R. Joel, and Fan, Shanhui. Method for computationally efficient design of dielectric laser accelerator structures. United States: N. p.,
Web. doi:10.1364/OE.25.015414.
Hughes, Tyler, Veronis, Georgios, Wootton, Kent P., England, R. Joel, & Fan, Shanhui. Method for computationally efficient design of dielectric laser accelerator structures. United States. doi:10.1364/OE.25.015414.
Hughes, Tyler, Veronis, Georgios, Wootton, Kent P., England, R. Joel, and Fan, Shanhui. 2017.
"Method for computationally efficient design of dielectric laser accelerator structures". United States.
doi:10.1364/OE.25.015414. https://www.osti.gov/servlets/purl/1369313.
@article{osti_1369313,
title = {Method for computationally efficient design of dielectric laser accelerator structures},
author = {Hughes, Tyler and Veronis, Georgios and Wootton, Kent P. and England, R. Joel and Fan, Shanhui},
abstractNote = {Here, dielectric microstructures have generated much interest in recent years as a means of accelerating charged particles when powered by solid state lasers. The acceleration gradient (or particle energy gain per unit length) is an important figure of merit. To design structures with high acceleration gradients, we explore the adjoint variable method, a highly efficient technique used to compute the sensitivity of an objective with respect to a large number of parameters. With this formalism, the sensitivity of the acceleration gradient of a dielectric structure with respect to its entire spatial permittivity distribution is calculated by the use of only two fullfield electromagnetic simulations, the original and ‘adjoint’. The adjoint simulation corresponds physically to the reciprocal situation of a point charge moving through the accelerator gap and radiating. Using this formalism, we perform numerical optimizations aimed at maximizing acceleration gradients, which generate fabricable structures of greatly improved performance in comparison to previously examined geometries.},
doi = {10.1364/OE.25.015414},
journal = {Optics Express},
number = 13,
volume = 25,
place = {United States},
year = {2017},
month = {6}
}