Nonlinear optics of condensed media

The laboratory conducts experimental and theoretical studies of the nonlinear dynamics of microparticles localized in radio frequency traps. In such systems, phase transitions between dynamic modes are possible, while the transition point is sensitive to external influences. Tracking the dynamics of a particle opens up new possibilities for detecting small forces.

At first glance, chaos is something that has no rules. But this is not the case. Dynamical systems move from ordered periodic to unpredictable chaotic dynamics according to certain rules. And what is interesting is that these rules can manifest themselves in systems that are completely different in nature - biological, sociological, and physical. Thus, the study of the processes of chaotic dynamics of microparticles allows us to explore literally the whole world around us. Why are microparticles trapped? Traps are characterized by different parameters, which are easy to control and see which way the dynamics will lead to chaos.

Liquid crystals combine the properties of liquids and crystals, possess internal order and high sensitivity to external influences. They are used in optoelectronics, sensors and displays. In nematic materials, electrohydrodynamic instabilities occur under the influence of an electric field — dynamic structures that cause scattering of transmitted light and fluctuations in its intensity. As the voltage increases, the size of the structures decreases, and the speed increases. Such liquid crystal cells can be used to modulate and generate controlled noise, so they are applicable in creating sources of truly random numbers and implementing computing systems (for example, Ising machines).

The laboratory is investigating the problem of optical cooling of solid-state systems, which include bulk crystals and nanocrystals doped with rare earth ions, as well as semiconductor heterostructures of various dimensions. The interest in obtaining optically cooled bulk crystals is related to the possibility of obtaining a compact, vibration-free solid-state cooler for use in various nanophotonics and optoelectronics systems. Optical cooling of nanoparticles is also in demand for the realization of the quantum state of a solid-state nanoobject in levitating optomechanics.

The ability to control the properties of semiconductor structures using optical and electric fields is becoming especially important for nanoscale systems used to create various photonics and optoelectronics devices. The effect of strong fields on nanostructures leads to a photoinduced rearrangement of both the energy spectrum of charge carriers and the vibrational spectrum of such structures. The laboratory conducts theoretical and experimental studies of the mechanisms of light-controlled energy transfer in electron-photon-phonon low-dimensional systems under conditions of optical and electrical stark effects.

The laboratory is developing a new class of accelerometers and gravimeters based on levitating optomechanical systems. Levitating nanoparticles used as a sensor in accelerometric measurements show sensitivity in measuring dynamic accelerations of the order of 1e-7 g Hz^(-0.5) (where g is the acceleration of gravity), the theoretical limit of possible sensitivity corresponds to 3e-12 g Hz^(-0.5). This paves the way for the creation of compact, high-precision sensors for basic research.

As part of the current study, we are studying the mechanical properties of cell membranes, which may form the basis for new diagnostic methods for neurodegenerative diseases. To develop techniques and understand the behavior of membranes under different conditions, various biological objects were used in experiments: from yeast (1) and erythrocytes (2) to HeLa cells, presumably carcinomas (3), and even tardigrades (4). This diversity allows us to evaluate the versatility of the approach and identify the features of the mechanical response of membranes that In the future, they may serve as sensitive biomarkers for pathological changes.