Dynamics of Femtosecond-Laser Modification of Glass

University Of California-Davis, Davis CA

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: Ultra-short pulse (femtosecond) laser structuring of glass is becoming increasingly important as a novel fabrication method to modify the properties of glass with three-dimensional spatial selectivity. Despite the fact that this technique has already been used for the fabrication of a variety of passive and active optical devices and lab-on-chip components, little is known about the processes by which the absorbed laser energy gets dissipated into the glass, thereby causing the structural changes. The objective of this project is to experimentally monitor the dynamics of femtosecond-laser modification in fused silica to gain a better understanding of the mechanisms involved and to determine how these depend on laser writing parameters. Highly trained graduate and undergraduate students will be the resources generated by the research in a cross-disciplinary setting. This project will offer them a unique opportunity by providing hands-on experience with state-of-the-art optical and materials characterization techniques. TECHNICAL DETAILS: The focus of the proposed research is to experimentally monitor the dynamics of femtosecond-laser modification in fused silica to gain a better understanding of the process. This is done by employing a number of different femtosecond-laser pump-probe experiments. In the first set of experiments the initial (peak) electron density resulting from the absorption of the femtosecond-laser pulse is determined as well as its dependence on laser-writing parameters such as laser wavelength, pulse energy, pulse duration and focusing conditions. The second set of experiments involves measuring the time evolution of the electron density. Once the electron density (or plasma) has decayed a hot liquid results, which then cools leaving the permanent modification. Time-dependent Raman measurements are used to probe the temperature of the hot liquid as a function of time until it has cooled completely. These experiments give important information about the mechanisms responsible for femtosecond-laser modification in glass. The findings have a major impact on the potential commercialization of this technique for optical device fabrication. This project involves foreign students and visitors through exchange programs provided by the NSF-International Materials Institute for New Functionality in Glass.