Direct laser writing of nanogratings using ultra-short pulses

Periodic nano-structures (nanogratings) formed by laser irradiation have found a wide range of applications over the past decade. Such nano-derivatives are formed to control the surface wetting of the materials, enhance sensitivity of the Raman scattering spectra, to improve the light absorption properties, to change the colour of the material used for light excitation, micro optical elements, bio-sensors, direct laser writing of Bragg reflectors and diffractive optical elements for optic fibers, etc.

Scientific novelty
Only in recent years, works emerged in the scientific literature related to formation of nanogratings in a volume of transparent material using femtosecond and picosecond pulses. In the fields of nanograting applications, the main parameter characterizing them is their period and it is therefore important to be able to control it. There is still little research works found in the scientific literature dedicated to direct laser writing of nanogratings, and this is a completely new area of science and technology that still has a lot of unknowns.

The purpose of the proposed PhD thesis is to investigate the peculiarities of nanograting formation in transparent media (quartz glass, sapphire) using ultra-short pulsed laser radiation. This is a very promising area of science and technology, as understanding the formation mechanisms of nanograting will optimize the process and write them quickly in a large area, thus extending their application capabilities. This will result in accelerated processing speed and improved quality that will improve nanograting writing technology.
Available equipment
The Department of Laser Technology (LTS), FTMC has a unique laser machining system capable of nanograting formation in volume of transparent materials. FTMC LTS has various equipment for characterizing samples and structures: optical microscopes; scanning electron microscope with EDS/WDS additives for chemical analysis; stylus profiler; atomic force microscope; spectrophotometers. FTMC LTS has a COMSOL Multiphysics software package for numerical modelling and simulation of physical processes.
For more information, please contact the theme supervisor M. Gedvilas.