Ultrashort pulse-induced periodic nanostructures in bulk glass: from fundamentals to applications in high-resolution microscopy

We investigated sub-wavelength structures, so-called nanogratings, induced by ultrashort laser pulses in the bulk of transparent materials. By using small angle x-ray scattering and focused ion beam milling we were able to show that nanogratings consist of sheet-like cavities with dimensions of (280 × 25 × 380) nm3 and (30 × 25 × 75) nm3. Their size remains constant with an increasing number of laser pulses while the number of sheets increases. This is in agreement with the continuously decreasing period obtained by diffraction measurements and SEM images. Furthermore, nanogratings were inscribed on different types of glass, such as ULE™ or borosilicate glasses. Different nanograting features, such as sheet thickness and periodicity, were obtained in borosilicate.Theoretical studies reveal that wavelength-scale plasma structures form during the interaction of laser light with glass. Their competition leads to the formation of periodic plasma patterns, which show the same orientation and period as nanogratings in glass (at low pulse numbers).Finally, nanograting-based waveplates have been successfully implemented in single shot optical sectioning analysis using the polarized-illumination-coded structured illumination microscopy (picoSIM) method.