Tsinghua University is committed to developing laser fabrication techniques for preparing surface micro/nanostructures and exploring their functional applications. We have established the ability to individually and finely control micro- and nanoscale features and control how they are combined to form different types of multilayer structures.
Surface functionalization via micro/nanostructures is not only a thriving research field inspired by bionics, but also important for a variety of practical applications. The key to realizing various surface functionalities is the fabrication of surface micro- and nanostructures with controllable sizes, layers, and compositions, which drives the continuous advancement of micro- and nanofabrication technologies.
Controlled in-situ deposition opens new possibilities for ultrafast laser surface micro/nanostructures
Researchers at the Laser Materials Processing Research Center, School of Materials Science and Engineering, Tsinghua University have spent several years developing laser fabrication techniques for preparing surface micro/nanostructures and exploring their functional applications. We have established the ability to individually and finely control micrometer- and nanoscale features and how they combine to form different types of multilayer structures. Functionalities and applications we have investigated include extreme wettability, anti-icing, broadband light absorption, structural color, solar water evaporation, thermal interface management, tribological properties, surface-enhanced Raman spectroscopy, and photoelectrocatalysis for energy applications.
Using ultrafast lasers to better control structure fabrication and to develop more flexible fabrication methods is one of the focuses of our ongoing research. In addition to controlling the ultrafast laser ablation process, we have recently demonstrated that particle deposition after in-situ ultrafast laser ablation of solid surfaces can also be controlled and used as a localized micro-additive process to build up layered surface structures. The formation of plasma plumes is a common phenomenon in pulsed laser ablation of solids.
Products from the plasma plume (e.g., nanoparticles) can be collected for use in external liquids (e.g., in the case of laser ablation in liquids) or substrates (e.g., in the case of pulsed laser deposition). In contrast, during ultrafast laser surface structuring, some nanoparticles in the plasma plume are deposited in situ back onto the irradiated surface.
For specific applications, the structural features deposited in situ play an important role in enhancing surface properties such as light absorption, sensitivity and energy conversion. However, whether and how to control the in situ deposition process remains an open question.
Our recent studies have shown the ability to control the in situ deposition process, e.g., by building fortress-like structures on top of microcone arrays, rather than just producing randomly distributed nanoparticles. The revealed mechanisms of laser-matter interactions could stimulate future research interest in exploring new possibilities of using ultrafast lasers to fabricate functional surface micro/nanostructures.
