Title

Time-frequency Control of Ultrafast Plasma Generation in Dielectrics

Department

Physics

Document Type

Article

Publication Date

12-1-2014

Abstract

This paper examines ultrafast laser-induced plasma generation in dielectrics by modeling ionization and pulse propagation in glass. Photoionization models for solids predict that the multi-photon ionization rate should increase for near-UV frequencies when compared to those in the visible or near-IR. Conversely, the frequency dependence of a Drude-type absorption by free electrons can produce an increased ionization yield through avalanching for frequencies in the IR. The simulations presented in this paper reveal how such frequency-dependent models influence the plasma formation during nonlinear pulse propagation in fused silica. It is further shown by a multi-rate equation model that the contribution from avalanching, when properly delayed, is reduced by an order of magnitude at near-IR frequencies throughout the propagation. A modified multi-rate equation is then introduced to model combinations of ultrashort high-frequency and low-frequency pulses that can maximize plasma generation while operating at the lowest possible fluences.

Journal

Journal of the Optical Society of America B

Journal ISSN

1520-8540

Volume

31

Issue

12

First Page

2973

Last Page

2980

Digital Object Identifier (DOI)

10.1364/JOSAB.31.002973