Deep Subwavelength Laser-Induced Periodic Surface Structures on Silicon as a Novel Multifunctional Biosensing Platform.

Strong light localization inside the nanoscale gaps provides remarkable opportunities for creation of various medical and biosensing platforms stimulating an active search for inexpensive and easily scalable fabrication at a sub-100 nm resolution. In this paper, self-organized laser-induced periodic surface structures (LIPSSs) with the shortest ever reported periodicity of 70 ± 10 nm were directly imprinted on the crystalline Si wafer upon its direct femtosecond-laser ablation in isopropanol. Appearance of such a nanoscale morphology was explained by the formation of a periodic topography on the surface of photoexcited Si driven by interference phenomena as well as subsequent down-scaling of the imprinted grating period Rayleigh-Taylor hydrodynamic instability.

Harnessing of inhomogeneously polarized Hermite-Gaussian vector beams to manage the 3D spin angular momentum density distribution.

We propose vector modes based on inhomogeneously polarized Hermite-Gaussian (HG) vector beams, providing complete structural conservation of the beams during propagation. Like uniformly polarized mode beams, these beams provide structural stability (or invariance) of both the intensity and the polarization state, in turn ensuring the stability of other field characteristics, including the angular momentum. We determine the conditions imposed on the HG mode composition in the transverse components of the electromagnetic field in order to control the three-dimensional characteristics of the field, such as intensity, polarization, and spin angular momentum (SAM).

On-Fly Femtosecond-Laser Fabrication of Self-Organized Plasmonic Nanotextures for Chemo- and Biosensing Applications.

Surface-enhanced Raman scattering (SERS) and surface-enhanced photoluminescence (SEPL) are emerging as versatile widespread methods for biological, chemical, and physical characterization in close proximity of nanostructured surfaces of plasmonic materials. Meanwhile, single-step, facile, cheap, and green technologies for large-scale fabrication of efficient SERS or SEPL substrates, routinely demonstrating both broad plasmonic response and high enhancement characteristics, are still missing. In this research, single-pulse spallative micron-size craters in a thick Ag film with their internal nanotexture in the form of nanosized tips are for the first time shown to demonstrate strong polarization-dependent enhancement of SEPL and SERS responses from a nanometer-thick covering Rhodamine 6G layer with average enhancement factors of 40 and 2 × 10(6), respectively.