## 1 Introduction  
Since the early days of physics, spectroscopy has been a platform for many fundamental investigations. One of the central concepts in spectroscopy is a resonance, with its corresponding resonant frequency. Types of spectroscopy can also be distinguished by the nature of the interaction between the electromagnetic field (EM-field) and the condensed matter (as examples, one may mention absorption and emission of light, Raman and Compton scattering, nuclear magnetic resonance, etc.). The first period in the development of spectroscopy is associated with atomic and molecular spectroscopy. Atoms of different elements have distinct spectra, and therefore, atomic spectroscopy allows for the identification of a sample's elemental composition. The spectral lines obtained by experiment and theory can be mapped to the Mendeleev Periodic Table of the Elements. Spectroscopic studies at this time, were central to the development of quantum mechanics. The second period in the making of spectroscopy is associated with a wide range of applications to different types of chemical substances: gases, liquids, crystals, polymers, etc. The combination of atoms or molecules into macroscopic samples leads to the creation of many-particle quantum states, whereby different materials have distinct spectra. Therefore, spectroscopy observations in a wide frequency range (from microwave until gamma-ray) became an irreplaceable tool for the identification of a sample's structure, chemical composition, quality, etc. in material engineering, physical chemistry, and biophysics. Recent progress in electronics and informatics is associated with the development of nanotechnologies and synthesis of different types of nano-objects. The distinct spectra became the attribute of nano-objects of various spatial configurations, but the same chemical composition. In this context, the future of spectroscopy development would probably be associated with the spectroscopy of a whole range of electronic devices, or their rather large components. This trend will provide tools of the tunable spectroscopy adapted for such types of tasks. The promising examples from this point of view are based on the strong and ultrastrong interactions of condensed matter with EM-field. The strong-coupling field-matter interaction is defined as a regime, in which the EM-field does not correspond to the small perturbation [1]. It leads to the periodical transitions of a two-level quantum system between its stationary states under the action of ac driving field (Rabi-oscillations--RO) [1]. The phenomenon was theoretically predicted by [PERSON] on nuclear spins in radio-frequency magnetic field [2], and afterwards, discovered in various physical systems, such as electromagnetically driven atoms [3], semiconductor quantum dots [4], and different types of solid-state qubits [5; 6; 7; 8; 9]. The simplest physical picture of the [PERSON] effect is given by the model of a single atom [1]. It can be essentially modified by a set of additional features, such as broken inversion symmetry [10], spatial RO propagation in the arrays of coupled Rabi-oscillators (Rabi-waves), and local field depolarization effects [11; 12; 13; 14; 15; 16]. The early quantum theory of electrical conductivity in crystal lattices by [PERSON], [PERSON] and [PERSON] [17; 18; 19; 20], led to the prediction that a homogeneous dc field induces an oscillatory, rather than uniform, motion of the electrons. These so-called Bloch-oscillations (BO) have never been observed in natural crystals because the scattering time of the electrons by the lattice defects is much shorter than the Bloch period [21]. In semiconductor superlattices, the larger spatial period leads to a much shorter Bloch period, and BO have been observed through the THz radiation of the electrons [22].