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We are interested in studying fundamental light-matter interactions, encompassing a  rich set of experiments, from quantum mechanical state-selective laser photolysis dynamics to fundamental photonics, and in parallel, applying the resulting understanding towards novel micro/nano-fabrication technologies and optical devices.

An important effort is geared towards Cover image2providing solutions to technological problems. We recently demonstrated a new type of micro-fabrication method inside silicon, enabling truly 3D laser-written elements employing buried or “in-chip” functionalities, created without altering wafer surfaces. This is similar to direct fabrication of 3D objects, commonly referred to as 3D printing, capturing the public imagination on a scale rapidly approaching that of consumer electronics revolutions of the last decades. Notably, until recently, there was no method for 3D fabrication deep inside Si. We developed such a method, which positions us with the capability to create in-chip optical elements and realise a rich set of 3D architectures.  One example is the first truly 3D Silicon photonics elements, created directly inside Si wafers. A further exciting direction is the unique integration towards novel in-chip photonics and microfluidic devices.

Towards this goal, we often exploit the inherent optical response of materials, primarily nonlinear laser interactions. We strive to create the conditions and understand the physics of interactions, that in many cases, lead to a rich dynamics between the laser and the material. In fact, in such a scenario, the laser-material system could be considered as a dynamically evolving entity, establishing various mechanisms that may be exploited for controlling or directing the evolution of its dynamics. This is a common theme we share with our closest collaborators,  Prof. Ömer Ilday (please see UFOLAB), Prof. Serim Ilday (also see Simply Complex Lab), Prof. Oguz Gülseren, all from Bilkent University. In this broader context, we are interested in figuring out how to control self-organized pattern forming mechanisms towards engineering functional structures  at multiple scales, from micro to nano scales, and various material platforms, from crystalline silicon to surface patterns on metals, semiconductors, insulators to colloidal nanoparticles. From a thermodynamical perspective, these systems operate far from equilibrium and pattern formation is typically driven by various feedback mechanisms, similar to our method for 3D microstructuring of Si. We also collaborate with Prof. Alpan Bek (Middle East Technical University). Previous collaborators include Prof. Demirci from Stanford University, and Prof. Houston from Cornell University.

Onur Tokel