Tomography of femtosecond laser structured objects inscribed in glass

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Laser processing of glass is a young research field, yet under immense and steadily-increasing development. Especially internal glass modifications and processing could lead to various new applications that make use of laser modified properties such as refractive index, volume, birefringence, glass network connectivity or thermodynamic phase states. Possible future technologies encompass a combination of subtractive and additive glass processing fabrication and miniaturization of optomechatronic components, nanofluidics, waveguides, or optical elements. These new devices with novel properties could have a strong impact on future biomedical, optomechatronic applications. Even though a considerable amount of work on this topic has been reported in literature, the nature of laser-induced transformations is still barely understood. The main objective of this proposal is to obtain a fundamental understanding of the ultra-short pulsed laser-glass interaction for short and longer pulse durations as well as for single pulse and multi pulse irradiation since it is known from literature and preliminary results that the glass-laser- interaction is strongly dependent on the glass type and laser parameters. While localized explanations for certain types of observed interactions do exist, they lack the necessary scope to predict the glass behavior for a different glass composition or irradiation parameters. Thus, the aim of this project is to gain sufficient information to formulate an adequate model of the laser glass interaction by connecting the spatially and time resolved observation of the laser glass interaction with Raman and Brillouin spectroscopy as well as transmission electron microscopy (TEM) and time-of-flight secondary mass spectrometry (TOF-SIMS) to detect structural and chemical modifications by which the interaction history of the glass with the laser pulse can be recovered. This makes detailed modelling of the glass-laser-interaction possible. The experiments and the model will give a continuous vision on the underlying processes in a range of nanometer to millimeter for time scales from pikosecond up to infinity. The new laboratory-based, nanometric x-ray microscopy (with the CZ Xradia 810 Ultra soon becoming available in Halle) can fill the missing observation gap between 1 µm and 50 nm. A special emphasis will be given to a chemical approach of the laser matter interaction. For that a large set of glasses will be synthesized and chemically sensitive techniques such as time resolved emission spectroscopy, TOF-SIMS and XRM will help to follow specifically each chemical element through all the underlying processes.