Título: Correlation of the refractive index change at the surface and inside phosphate glass upon femtosecond laser irradiation

Autor: Puerto Garcia, Daniel; Siegel, Jan; Ferrer, Andres; Hernandez-Rueda, Javier; Solis, Javier

Resumen: [EN] A study of the surface modification induced by single femtosecond laser pulses in phosphate glass has revealed surface swelling at fluences just below the ablation threshold. This behavior is different from that observed in other dielectric materials. Optical micrographs obtained with monochromatic light show a pattern of Newton rings within the swollen region whose number scales inversely with the illumination wavelength, acting as a micro Fabry-Perot etalon. The swollen surface layer has lower refractive index than the bulk glass and can reach a maximum thickness of 820 nm. We relate these findings to results obtained during subsurface waveguide writing inside phosphate glass, which also show a refractive index decrease at energies near threshold for waveguide fabrication. We have identified low density free-electron plasma to be the trigger of the refractive index change. © 2012 Optical Society of America.

Descripción: This paper was published in JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/josab/viewmedia.cfm?URI=josab-29-10-2665&seq=0&origin=search. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law

URI: http://hdl.handle.net/10251/28774

Fecha: 2012-10

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