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 Title
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