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Laser amplification in excited dielectrics

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  • Thomas Winkler, University of Kassel
  • ,
  • Lasse Haahr-Lillevang
  • ,
  • Cristian Sarpe, University of Kassel
  • ,
  • Bastian Zielinski, University of Kassel
  • ,
  • Nadine Goette, University of Kassel
  • ,
  • Arne Senftleben, University of Kassel
  • ,
  • Peter Balling
  • Thomas Baumert, University of Kassel

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400nm femtosecond laser pulse is coherently amplified inside an excited sapphire sample on a scale of a few micrometres. Simulations strongly support the proposed two-photon stimulated emission process, which is temporally and spatially controllable. Consequently, we expect applications in all fields that demand strongly localized amplification.

Original languageEnglish
JournalNature Physics
Pages (from-to)74-79
Number of pages6
Publication statusPublished - Jan 2018

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