Nonlinear effects during interaction of femtosecond doughnut-shaped laser pulses with glasses: Overcoming intensity clamping

Nadezhda M. Bulgakova, Vladimir P. Zhukov, Mikhail P. Fedoruk, Alexander M. Rubenchik

Research output: Chapter in Book/Report/Conference proceedingConference contributionResearchpeer-review


Interaction of femtosecond laser pulses with a bulk glass (fused silica as an example) has been studied numerically based on non-linear Maxwell's equations supplemented by the hydrodynamics-type equations for free electron plasma for the cases of Gaussian linearly-polarized and doughnut-shaped radially-polarized laser beams. For Gaussian pulses focused inside glass (800 nm wavelength, 45 fs duration, numerical aperture of 0.25), the free electron density in the laser-excited region remains subcritical while the locally absorbed energy density does not exceed ∼2000 J/cm3 in the range of pulse energies of 200 nJ - 2 μJ. For doughnut-shaped pulses, the initial high-intensity ring of light is shrinking upon focusing. Upon reaching a certain ionization level on its way, the light ring splits into two branches, one of which shrinks swiftly toward the beam axis well before the geometrical focus, leading to generation of supercritical free electron density. The second branch represents the laser light scattered by the electron plasma away from the beam axis. The final laserexcited volume represents a tube of 0.5-1 μm in radius and 10-15 μm long. The local maximum of absorbed energy can be more than 10 times higher compared to the case of Gaussian beams of the same energy. The corresponding pressure levels have been evaluated. It is anticipated that, in the case of doughnut-shaped pulses, the tube-like shape of the deposited energy should lead to implosion of material that can be used for improving the direct writing of high-refractive index optical structures inside glass or for achieving extreme thermodynamic states of matter.

Original languageEnglish
Title of host publicationNonlinear Optics and Applications X
EditorsM Bertolotti, JW Haus, AM Zheltikov
Number of pages8
ISBN (Electronic)9781510609570
ISBN (Print)978-1-5106-0957-0
Publication statusPublished - 1 Jan 2017
Event7th Nonlinear Optics and Applications Conference - Prague, Czech Republic
Duration: 24 Apr 201725 Apr 2017

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


Conference7th Nonlinear Optics and Applications Conference
CountryCzech Republic


  • doughnut-shaped laser pulses
  • free electron plasma
  • Gaussian laser pulses
  • glass
  • Laser beam propagation
  • Maxwell's equations
  • non-linear processes


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