EventDr. Yves Bellouard

Femtosecond laser three-dimensional exposure of silica substrate in the non-ablative regime: from laser-induced modifications to applications

Thanks to non-linear absorption processes, non-ablative femtosecond laser pulses applied to fused silica induce bulk morphological transformations in the material associated with a variety of local changes of physical properties. These structural changes includes locally densified glass matrices, self-organized nanostructures as well as the formation of polymorphic phases. As a direct consequence, the material experiences localized volume variation resulting in either tensile or compressive stress, which intensity and direction are both controlled by the pulse energy and the laser polarization, respectively.

Here, we will discuss these laser modifications, both from the viewpoint of stress-states and structural changes induced in the material. In particular, we will show how these controlled states along with this ability to tune material properties can be used for novel applications in optomechanics, such as tunable Duffing oscillators, embedded optical wave plate, but also, as a means to investigate mechanical properties at the small scales and for the packaging of complex optical devices. Finally, we will conclude by showing the existence of intermittent behavior observed while writing in material and illustrates how this apparent erratic behavior bearing randomness provides useful information related to fracture mechanics at small scales.

Flexures-k

About The Speaker

Yves-Bellouard

Dr. Yves Bellouard is Associate Professor in Microengineering at Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, where he heads the Galatea lab and the Richemont Chair in micromanufacturing.

He received a BS in Theoretical Physics and a MS in Applied Physics from Université Pierre et Marie Curie in Paris, France in 1994-1995 and a PhD in Microengineering from Ecole Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland in 2000. Before joining EPFL in 2015, he was Associate Professor at Eindhoven University of Technologies (TU/e) in the Netherlands and prior to that, Research Scientist at Rensselaer Polytechnic Institute (RPI) in Troy, New York for about four years where he started working on femtosecond laser processing of glass materials.

His current research interests are on new paradigms for system integration at the microscale and in particular laser-based methods to tailor material properties for achieving higher level of integration in microsystems, like for instance integrating optics, mechanics and fluidics in a single monolith. These approaches open new opportunities for direct-write methods of microsystems (3D printing).