IPAC2022 - List of Authors (van Tilborg, J.)

Paper	Title	Page
TUPOST009	Online Correction of Laser Focal Position Using FPGA-Based ML Models	857
	J.A. Einstein-Curtis, S.J. Coleman, N.M. Cook, J.P. Edelen RadiaSoft LLC, Boulder, Colorado, USA S.K. Barber, C.E. Berger, J. van Tilborg LBNL, Berkeley, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Numbers DE-SC 00259037 and DE-AC02-05CH11231. High repetition-rate, ultrafast laser systems play a critical role in a host of modern scientific and industrial applications. We present a prototype diagnostic and correction scheme for controlling and determining laser focal position at 10 s of Hz rate by utilizing fast wavefront sensor measurements from multiple positions to train a focal position predictor. This predictor is used to determine corrections for actuators along the beamline to provide the desired correction to the focal position on millisecond timescales. Our initial proof-of-principle demonstrations leverage pre-compiled data and pre-trained networks operating ex-situ from the laser system. We then discuss the application of a high-level synthesis framework for generating a low-level hardware description of ML-based correction algorithms on FPGA hardware coupled directly to the beamline. Lastly, we consider the use of remote computing resources, such as the Sirepo scientific framework* , to actively update these correction schemes and deploy models to a production environment. * M.S. Rakitin et al., "Sirepo: an open-source cloud-based software interface for X-ray source and optics simulations", Journal of Synchrotron Radiation 25, 1877-1892 (Nov 2018).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST009
About •	Received ※ 20 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOTK062	Thermal Modeling and Benchmarking of Crystalline Laser Amplifiers	2921
	D.T. Abell, D.L. Bruhwiler, P. Moeller, R. Nagler, B. Nash, I.V. Pogorelov RadiaSoft LLC, Boulder, Colorado, USA Q. Chen, C.G.R. Geddes, C. Tóth, J. van Tilborg LBNL, Berkeley, California, USA N.B. Goldring STATE33 Inc., Portland, Oregon, USA
	Funding: This work is supported by the US Department of Energy, Office of High Energy Physics under Award Numbers DE-SC0020931 and DE-AC02-05CH11231. Ti:sapphire crystals constitute the lasing medium of a class of lasers valued for their wide tunability and ultra-short, ultra-high intensity pulses. When operated at high power and high repetition rate (1kHz), such lasers experience multiple effects that can degrade performance. In particular, thermal gradients induce a spatial variation in the index of refraction, hence thermal lensing. Using the open-source finite-element code FEniCS*, we solve the relevant partial differential equations to obtain a quantitative measure of the disruptive effects of thermal gradients on beam quality. We present thermal simulations of a pump laser illuminating a Ti:sapphire crystal. From these simulations we identify the radial variation in the refractive index, and hence the extent of thermal lensing. In addition, we present analytic models used to estimate the effect of thermal gradients on beam quality. This work generalizes to other types of crystal amplifiers. S. Cho, et al., Appl. Phys. Express, 11:092701, 2018. M. Born & E. Wolf, Principles of Optics, Cambridge Univ. Press, 1980. * The FEniCS computing platform, https://fenicsproject.org
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK062
About •	Received ※ 13 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOTK063	Open Source Software to Simulate Ti:Sapphire Amplifiers	2925
	D.L. Bruhwiler, D.T. Abell, B. Nash RadiaSoft LLC, Boulder, Colorado, USA Q. Chen, C.G.R. Geddes, C. Tóth, J. van Tilborg LBNL, Berkeley, California, USA N.B. Goldring STATE33 Inc., Portland, Oregon, USA
	Funding: This work is supported by the US Department of Energy, Office of High Energy Physics under Award Numbers DE-SC0020931 and DE-AC02-05CH11231. The design of next-generation PW-scale fs laser systems, including scaling to kHz rates and development of new laser gain media for efficiency, will require parallel multiphysics simulations with realistic errors and nonlinear optimization. There is currently a lack of broadly available modeling software that self-consistently captures the required physics of gain, thermal loading and lensing, spectral shaping, and other effects required to quantitatively design such lasers.* We present initial work towards an integrated multiphysics capability for modeling pulse amplification in Ti:Sa lasers. All components of the software suite are open source. The Synchrotron Radiation Workshop (SRW)** is being used for physical optics, together with Python utilities. The simulations are being validated against experiments. * R. Falcone et al., Brightest Light Initiative Workshop Report (2019). ** https://github.com/ochubar/srw
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK063
About •	Received ※ 14 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 16 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Online Correction of Laser Focal Position Using FPGA-Based ML Models

857

J.A. Einstein-Curtis, S.J. Coleman, N.M. Cook, J.P. Edelen
RadiaSoft LLC, Boulder, Colorado, USA
S.K. Barber, C.E. Berger, J. van Tilborg
LBNL, Berkeley, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Numbers DE-SC 00259037 and DE-AC02-05CH11231.
High repetition-rate, ultrafast laser systems play a critical role in a host of modern scientific and industrial applications. We present a prototype diagnostic and correction scheme for controlling and determining laser focal position at 10 s of Hz rate by utilizing fast wavefront sensor measurements from multiple positions to train a focal position predictor. This predictor is used to determine corrections for actuators along the beamline to provide the desired correction to the focal position on millisecond timescales. Our initial proof-of-principle demonstrations leverage pre-compiled data and pre-trained networks operating ex-situ from the laser system. We then discuss the application of a high-level synthesis framework for generating a low-level hardware description of ML-based correction algorithms on FPGA hardware coupled directly to the beamline. Lastly, we consider the use of remote computing resources, such as the Sirepo scientific framework* , to actively update these correction schemes and deploy models to a production environment.
* M.S. Rakitin et al., "Sirepo: an open-source cloud-based software interface for X-ray source and optics simulations", Journal of Synchrotron Radiation 25, 1877-1892 (Nov 2018).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST009

About •

Received ※ 20 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOTK062

Thermal Modeling and Benchmarking of Crystalline Laser Amplifiers

2921

D.T. Abell, D.L. Bruhwiler, P. Moeller, R. Nagler, B. Nash, I.V. Pogorelov
RadiaSoft LLC, Boulder, Colorado, USA
Q. Chen, C.G.R. Geddes, C. Tóth, J. van Tilborg
LBNL, Berkeley, California, USA
N.B. Goldring
STATE33 Inc., Portland, Oregon, USA

Funding: This work is supported by the US Department of Energy, Office of High Energy Physics under Award Numbers DE-SC0020931 and DE-AC02-05CH11231.
Ti:sapphire crystals constitute the lasing medium of a class of lasers valued for their wide tunability and ultra-short, ultra-high intensity pulses. When operated at high power and high repetition rate (1kHz), such lasers experience multiple effects that can degrade performance. In particular, thermal gradients induce a spatial variation in the index of refraction, hence thermal lensing*. Using the open-source finite-element code FEniCS***, we solve the relevant partial differential equations to obtain a quantitative measure of the disruptive effects of thermal gradients on beam quality. We present thermal simulations of a pump laser illuminating a Ti:sapphire crystal. From these simulations we identify the radial variation in the refractive index, and hence the extent of thermal lensing. In addition, we present analytic models used to estimate the effect of thermal gradients on beam quality. This work generalizes to other types of crystal amplifiers.
* S. Cho, et al., Appl. Phys. Express, 11:092701, 2018.
** M. Born & E. Wolf, Principles of Optics, Cambridge Univ. Press, 1980.
*** The FEniCS computing platform, https://fenicsproject.org

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK062

About •

Received ※ 13 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOTK063

Open Source Software to Simulate Ti:Sapphire Amplifiers

2925

D.L. Bruhwiler, D.T. Abell, B. Nash
RadiaSoft LLC, Boulder, Colorado, USA
Q. Chen, C.G.R. Geddes, C. Tóth, J. van Tilborg
LBNL, Berkeley, California, USA
N.B. Goldring
STATE33 Inc., Portland, Oregon, USA

Funding: This work is supported by the US Department of Energy, Office of High Energy Physics under Award Numbers DE-SC0020931 and DE-AC02-05CH11231.
The design of next-generation PW-scale fs laser systems, including scaling to kHz rates and development of new laser gain media for efficiency, will require parallel multiphysics simulations with realistic errors and nonlinear optimization. There is currently a lack of broadly available modeling software that self-consistently captures the required physics of gain, thermal loading and lensing, spectral shaping, and other effects required to quantitatively design such lasers.* We present initial work towards an integrated multiphysics capability for modeling pulse amplification in Ti:Sa lasers. All components of the software suite are open source. The Synchrotron Radiation Workshop (SRW)** is being used for physical optics, together with Python utilities. The simulations are being validated against experiments.
* R. Falcone et al., Brightest Light Initiative Workshop Report (2019).
** https://github.com/ochubar/srw

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK063

About •

Received ※ 14 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 16 June 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)