Summer School Abstracts

Dmitry Skryabin, Bath University, UK
“Maths and physics of the microresonator frequency combs”
Abstract: I will put a hystorical perspective on the interpretation of the properties of the soliton and periodic solutions of the Lugiato-Lefever model widely applicable in our days to describe frequency comb generation in micorresonators. I will review at the tutorial level and with the emphasys on theory and modelling a stream of recent results on the microresonator comb generation in the systems with Kerr, quadratic and Raman nonlinearities and in some of the lasing devices.

Oleg Prudnikov, Institute of Laser Physics, Novosibirsk
“Quantum sensors based on atom-optical interferometry”
Abstract: Advances in laser cooling and manipulation of an ensemble of neutral atoms by laser waves opened up new perspectives in the development of modern physics and in the realization of new generation devices based on the basic principles of quantum physics — quantum sensors. Ultracold atoms are widely used in the development of a new class of quantum devices such as modern optical frequency and time standards that can reach fractional frequency uncertainties of below 10-18, as well as for constructing modern atomic interferometers based on matter waves. Matter-wave interference enables the investigation of physical interactions at their fundamental quantum level and forms the basis of high-precision inertial sensors and for different application like development of gravimeters, gravitational field gradientometers for precision gravitational field sensing, development of high sensitive accelerometers and gyros for precision inertial navigation systems. Such devises allow combining high metrological characteristics of quantum sensors with compactness and mobility. Along with many fundamental applications, these highly sensitive atomic interferometers have great potential in the development of satellite-free navigation systems, the inertial navigation systems, which is an extremely important scientific and technical task. The key advantage of such systems is their noise immunity, as well as their performance in conditions where it is impossible to use standard systems, for example, in difficult terrain and underwater receiver locations. In some cases, the presence of such safe, stable and autonomous navigation systems is absolutely necessary.

 Dmitry Kolker, Novosibirsk State University
“MID-IR optical parametric oscillators for different applications”
Abstract: The MID –IR spectral region is of great interest to different applications. In this spectral range there are a number of fundamental vibrational-rotational absorption lines of various gases. These gases are provisionally located by using of various methods of laser spectroscopy: Photo acoustic spectroscopy, differential absorption LIDAR systems and others. The main “windows of transparency” of the atmosphere are located in the ranges of 3-5 microns and 8-12 microns. Fan-out quasi-phase-matched nonlinear-optical structures are attractive for laser frequency down-conversion from near-IR to mid-IR region in optical parametric oscillator (OPO), or wise version for up-conversion by second-harmonic generation (SHG). A variation of period for the same propagation direction inside of the fan-out structure provides flexible phase-matching condition for nonlinear-optical interactions. I will talk also about OPO systems pumped by 1-2 mkm laser (Nd:YLF, Nd:YAG, Tm:YAG, Ho:YAG and cascade OPO) based on LiGaS2, HgGa2S4, BaGa4S7, BaGa4Se7 nonlinear crystals and OP-GaAs (OP-GaP) structures.

Morteza Kopae, Aston University, UK
A fibre-optic communication system based on the Inverse scattering transform
Abstract: The fibre channel is substantially different from other telecommunication media used over the past century. It provides means to have a directive signal propagation but poses some new challenges that the available, long-thought methods cannot overcome. The convenient approach of accommodating the solutions, which are designed for the well-known linear communication, to these new challenges, is shown to only partially exploit the resources that are made available by fibre. On the other hand, a radical new standpoint where the physical characteristics and traits of the fibre are considered when designing the communication system seems to put forward new possibilities to reach the limits of fibre-optic communication. Using inverse scattering transform (IST) is an attempt along this way of problem-solving when a communication system is tailored to the evolution of signal as it travels in fibre. Different types of IST and various applications of it in a fibre-optic system will be explained and the latest experimental results will be discussed.

Alexey Balakin, Institute of Applied Physics, Nizhniy Novgorod,
Coherent propagation and compression of laser pulses in optical multi-core fibre
Abstract: A review of the study of the self-action dynamics of the wave field in an array of weakly coupled passive and active optical fibers is presented. Possibilities and limitations on the capture of radiation into the a single fiber are shown. Stable exact solutions are found for intense wave beams, allowing long-distance coherent transport of radiation in a small-sized set of optical fibers. The total beam power in this case can exceed several times the critical power of self-focusing in the continuous medium. The self-compression mechanism of laser pulses was proposed basing on the found solutions.

Anatoly M. Kamchatnov, Institute of Spectroscopy, Troitsk, Moscow
Dispersive shock waves in nonlinear optics
Abstract: The lecture gives an introduction to main results and theoretical methods of investigation of dispersive shock waves in nonlinear optics. After short presentation of the most spectacular experimental observations of dispersive shock waves in various physical situations, we review the basic method of their theoretical description – Whitham theory of modulations of nonlinear waves. It will be shown how to find the wave breaking moment in evolution of nonlinear pulse after which the dispersive shock wave starts to form, and how to calculate the main parameters of the shock for given initial data. The main attention is paid to the general theory applicable to wide class of nonlinear wave equations beyond the celebrated class of so-called “completely integrable equations”. Thus, the knowledge of the Inverse Scattering Transform method is not necessary for understanding the lecture.

Alexey Taichenachev, Institute of Laser Physics, Novosibirsk
Generalized Ramsey spectroscopy of forbidden transitions for atomic clocks
Abstract: We present a review of the rapidly growing field of generalized Ramsey spectroscopy followed by a detailed discussion of several novel techniques that were developed and studied in our group: hyper-Ramsey spectroscopy, auto-balanced Ramsey spectroscopy, displaced frequency-jump Ramsey spectroscopy and combined error signal spectroscopy. The use of these techniques in optical atom clocks as well as in atom clocks based on coherent population trapping has reduced instabilities from variations in light-shift parameters by several orders of magnitude, opening ways to new horizons.

Oleg Morozov, Kazan National Research Technical University
Symmetry breaking as a source of information in microwave photonics
Abstract: The relationship of symmetry / asymmetry and information is considered by modern science in various aspects, covering both the fundamental questions of the self-development of matter at all its structural levels, and the applied questions of the development of individual fields of science. In a sense, the categories of symmetry and information are opposite. An increase in the object symmetrizing signs should lead to a decrease in the amount of information. Conversely, a decrease in the number of symmetry elements in an object should always be associated with an increase in the amount of structural information. Moreover, these relations are not always linear. These questions are examined in a lecture in relation to and from the standpoint of the development of microwave photonics systems. Topics included: generation of special signals (for example, solitons), design of transmission links and filters of microwave signals, optical vector network analyzers and sensor systems (with a new type of fiber Bragg gratings — addressable). All these systems use symmetric and asymmetric amplitude-phase forming and probing methods and phase-amplitude methods for processing information generated in them.

Boris Luk’yanchuk, Lomonosov Moscow State University
Higher order Fano-resonances in microsphere: extreme effects in field localization
Abstract: We reveal optical super-resonance modes supported by dielectric microspheres. These resonances present high order Fano resonances with extra high values of electric and magnetic fields. This permits to enhance the magnetic field of light (which is typically small) to a few order of magnitudes for optical frequencies. It produces magnetic nanojet and giant magnetic fields within the particles with high refractive index. It is attractive for a number of promising applications, e.g. enhanced absorption effect, ablation caused by magnetic pressure, etc.

Natalia G. Berloff, Skolkovo Institute of Science and Technology and Department of Applied Mathematics and Theoretical Physics, University of Cambridge
Polaritonic networks as a route to unconventional computing
Abstract: For a long time two pervasive topics of modern science — dynamics of coupled oscillators and simulations of many-body solid state systems — have barely crossed their paths.
Complex dynamic behaviour of networks of coupled oscillators arise in various scientific disciplines ranging from biology, physics, and chemistry to social and neural networks as well as established and emerging technological applications. Such networks are paradigmatic models for understanding the mechanism of various different collective phenomena. At the other end of spectrum of nonlinear dynamical studies lies the complex many-body solid-state systems that are often considered as powerful platforms for simulating various elaborate Hamiltonians. A number of systems were realised using neutral atoms, ions, electrons in semiconductors, polar molecules, nuclear spins, superconducting circuits etc. These are typically equilibrium systems that realise ground or excited states of their structure Hamiltonians. Recently, photonic and polaritonic lattices have emerged as promising platforms for many-body quantum and classical simulations. These systems are typically of a gain-dissipative nature, capable of symmetry breaking and spontaneous pattern formation, and have constant nonzero fluxes even at the steady state. Furthermore, as I argue in my talk, when the lattice elements have photonic component and the gain-dissipative nature the wavefunction packets evolve, interact and synchronise in a close resemblance to the coupled oscillators that governed by the universal order parameter equations. As a result, on one hand, many classical phenomena found in such networks can be explained or predicted by the behaviour of the corresponding system of coupled oscillators, one the other hand, strong nonlinearities, spin-orbit coupling, sensitivity to magnetic fields, and individual site control greatly enrich possible states and dynamical regimes that can be generated in such lattices.
In my talk I will propose and theoretically justify the use of networks of exciton-polaritons (polaritonic networks) as a flexible universal platform to realise a vast array of known and extensively studied systems of coupled oscillators such as Kuramoto, Sakaguchi-Kuramoto, Stuart-Landau, Lang-Kobayashi oscillators and beyond.
The networks of polariton condensates are therefore capable of implementing various regimes acting as analogue Hamiltonian optimisers, producing Chimera states, exotic spin glasses and large scale secondary synchronization of oscillations, probe new exotic dynamical regimes and to create novel states of matter.

Alexander Apolonskiy, Ludwig Maximilian University of Munich, Germany and Max Planck Institute of Quantum Optics, Garching, Germany
Mid-infrared spectroscopies for studying human biofluids
Abstract: In the absence of objective medical diagnostics capable of detecting a broad set of diseases, photonics technologies are now considered as a promising way to establish them. Due to fundamental absorption bands, mid-infrared spectroscopies of different types allow to detect organic molecules even at low concentrations. Nowadays, there is a growing interest in detecting specific organic molecules of human biofluids in relation to diseases. The status of the most promising types of spectroscopies for studying biofluids will be discussed in terms of their critical physical parameters, and the best results of blood and breath studies known so far will be shown.