Theoretical seminar | 17 May 2023

The presentation will cover two topics:
(1) Hyperbolic metamaterials (HMM) are known to have remarkable optical properties, including propagation of evanescent modes and negative refraction. In this work, the design of the imaging system consisting of two adjoining HMMs with different types of hyperbolic dispersion is proposed. In such a system, light from a point source placed inside one HMM propagates along the resonant cone, is negatively refracted at the interface between metamaterials, and produces a deeply subwavelength image in the second HMM. The results of the numerical study will be presented.
(2) Laser-induced periodic surface structures (LIPSS) are a periodic modulation of the surface relief that occurs on solids under laser radiation with the energy near the damage threshold due to scattering-interference effects, material melting and ablation, and other physical mechanisms. Relatively recently, the formation of thermochemical LIPSS (TLIPSS) resulting from periodically patterned oxidation of the material has been discovered. Highly uniform TLIPSS can be fabricated on metal films via lateral scanning of the surface with femtosecond (fs) laser pulses. In this work, the TLIPSS formation on films of metals (Cr, Ti, Hf) and semiconductors (Si, Ge) using fs laser pulses is studied experimentally. The effects of film thickness, laser processing parameters, reacting environment on the morphology, chemical composition, and optical properties of TLIPSS were investigated.

Main paper/arXiv, related to the seminar, and other references

(1) Bronnikov, K., Arriaga, J., Krokhin, A. & Drachev, V. P. Sub-Diffraction-Limit Imaging System with two Interfacing Hyperbolic Metamaterials. Phys. Rev. Applied 16, 044054 (2021).
(2) 1. Dostovalov, A. V., Korolkov, V. P., Okotrub, K. A., Bronnikov, K. A. & Babin, S. A. Oxide composition and period variation of thermochemical LIPSS on chromium films with different thickness. Opt. Express, OE 26, 7712–7723 (2018).
2. Dostovalov, A., Bronnikov, K. et al. Hierarchical anti-reflective laser-induced periodic surface structures (LIPSSs) on amorphous Si films for sensing applications. Nanoscale 12, 13431–13441 (2020).
3. Bronnikov, K. et al. Uniform subwavelength high-aspect ratio nanogratings on metal-protected bulk silicon produced by laser-induced periodic surface structuring. Appl. Phys. Lett. 119, 211106 (2021).
4. Bronnikov, K. et al. Regulating Morphology and Composition of Laser-Induced Periodic Structures on Titanium Films with Femtosecond Laser Wavelength and Ambient Environment. Nanomaterials 12, 306 (2022).