Vol 117, No 1 (2023): ТЕМАТИЧЕСКИЙ БЛОК: СОВРЕМЕННЫЕ ПРОБЛЕМЫ ФОТОНИКИ ИНФРАКРАСНОГО ДИАПАЗОНА

Infrared optics is extremely widespread in modern science and technology. Almost all telecommunications equipment operates in the infrared range, thermal radiation is also most pronounced in the infrared region of the spectrum. Night vision devices are based on its detection. Therefore, infrared radiation plays an important role in nearfield radiative heat transfer and is also used in spectroscopy and many other scientific applications. In recent years, advanced nanostructuring techniques aimed at manipulating light at the nanoscale have become widespread. In particular, photonic crystals, metasurfaces and nanoresonators are actively used. In this work, we consider the possibilities of using two-dimensional layered structures in the optical and infrared ranges. In particular, we consider the possibility of using Dyakonov surface waves in confined media, as well as collective resonances in the lattices of plasmonic nanoparticles. Both types of structures make it possible to localize light on the submicroscale, enhance the interaction of light with matter, and effectively control the propagation of electromagnetic waves.

The processes of energy migration in upconvertion nanocrystals (UCNPs) governing the quantum efficiency under pulse excitation at 975 nm, which is a decisive factor for the widespread use of UCNPs, have been studied. The treatment by picosecond laser radiation leads to a controlled nanotransformation of a three-dimensional luminescent structure into a one-dimensional one through the formation of particles with a structure resembling a “medusa”.
The upconversion process in the one-dimensional structure occurs due to the energy migration between Yb3+, as in the case of nanoparticles. An approach is proposed for evaluating the efficiency of nonradiative energy transfer in a complex of UCNPs with a fluorophore. It takes into account the contribution of energy migration between sensitizer ions. The use of UCNPs in photothermal therapy is shown to be promising due to the large absorption cross section of the Yb3+ sensitizer. The cellular response to hyperthermia involving UCNPs is demonstrated by measuring heat shock protein expression.

The structure and main parameters of photosensor structures based on quasi-two-dimensional layers of elements of groups IV, V, VI and VIII of D.I. Mendeleev, such as reduced graphene oxide (rGO), tin telluride (SnTe), bismuth telluride (Bi2Te3), platinum selenide (PtSe2), material based on nitrogen-substituted graphene (C3N) are described. New photosensitive elements based on arrays of arbitrarily oriented 2D-Bi2Te3 and reduced graphene oxide (rGO) nanolayers, heterostructures from composite two-dimensional SnTe/rGO nanoparticles, rGO/(SnTe+rGO) and rGO/Bi2Te3 heterostructures have been synthesized for the first time. On the synthesized elements, photosensitivity is implemented in various areas of electromagnetic radiation. Based on the rGO and 2D-Bi2Te3, a field-effect phototransistors were fabricated, in which the effect of the dependence of the shape of the Ids(Vg) curves on illumination by various radiation sources was discovered for the first time, which opens up prospects for creating photosensors with voltage-controlled spectral sensitivity.

A new physical effect of strong low-temperature broadband (2–40 μm) IR photoconductivity in the p–n junction of silicon formed by an n-hyperdoped layer on a p-doped substrate has been studied. Broadband IR photoconductivity is provided by a clearly pronounced discrete spectrum of neutral and singly ionized donor states of the substitutional atomic impurity and sulfur clusters near the bottom of the conduction band (the so-called “intermediate” band up to 0.6 eV wide), the population distribution within which is smooth over the spectrum, well pronounced, and controlled in amplitude by thermal excitation in the range of 5–250 K. As a result, on the basis of a single silicon photocell, the choice of temperature mode allows registration of radiation in the far-near infrared range for a wide range of diverse practical problems – solar energy, thermal imaging and bioimaging.

In this review we present the results of the interdisciplinary RFBR project N18-29-20079. The project was aimed on the creation of room-temperature bulk and fiber chalcogenide glass lasers operating at wavelengths exceeding 4 μm. Before this investigation this wavelength range was inaccessible for glass lasers. Record purity Pr3+, Tb3+, Ce3+ and Nd3+ doped chalcogenide glass samples were synthesized. The analysis of their luminescent properties has made it possible to choose the promising laser transitions and the ways of their optical pumping. Lasing has been demonstrated on a number of 4.5–6 μm optical transitions of Ce3+, Pr3+ and Tb3+ ions. Previously all these transitions were never used in lasers. In a bulk sample of cerium-doped selenide glass, an output energy of up to 43 mJ per pulse and tuning in the 4.5–5.6 µm spectral range were obtained. In a continuously pumped composite optical fiber with terbium-doped selenide core in an undoped sulfide cladding 100 mW output power at ~ 5.25 µm was obtained.

The ratio of the velocity of laser-field-induced motion of electrons induced by tunneling ionization and speed of light is one of the key physical factors determining the efficiency of nonlinear optical processes in plasma media. We show that the use of powerful ultrashort pulses with a central wavelength in the mid-infrared range enhance plasma nonlinearities in air associated primarily with plasma currents induced by a intense laser field. On this basis, it is possible to implement laser-plasma schemes of the efficient generation of coherent broadband microwave and terahertz radiation, i.e. microwave–terahertz supercontinuum.