Monochromatic Microwave Radiation Research Articles

Acoustoelectric Study of Microwave-Induced Current Domains.

Surface acoustic waves (SAW) have been utilized to investigate the properties of a two-dimensional electron system subjected to a perpendicular magnetic field and monochromatic microwave radiation in the regime where the so-called microwave-induced zero-resistance states form. Contrary to conventional magnetotransport in Hall bar and van der Pauw geometries, the collimated SAW beam probes only the bulk of the electronic system exposed to this wave. Clear signatures appear in the SAW propagation velocity, corroborating that neither contacts nor sample edges are a root source for their emergence. By virtue of the directional nature of this probing method and with the assistance of theoretical modeling, we were able to demonstrate that the SAW response depends on the angle between its propagation vector and the orientation of domains that spontaneously form when zero-resistance is observed in transport. This confirms in unprecedented manner the formation of an inhomogeneous phase under these nonequilibrium conditions.

Thermally induced monochromatic microwave generation in magnon polaritons

We propose thermal induced generation of monochromatic microwave radiation in magnon-polariton. Mechanism of thermal to microwave energy transformation is based on intrinsic energy loss compensation of coupled magnon and microwave cavity oscillators by thermal induced "negative damping". A singularity at an exceptional point is achieved when at the critical value of "negative damping" the damping of the system is fully compensated. At the exceptional point, the input energy is equally distributed between the magnon and photon subsystems of the magnon-polariton. The efficiency of transformation of thermal energy into useful microwave radiation is estimated to be as large as 17 percent due to magnon-photon coupling mediated direct conversation of spin current into microwave photons.

Evidence for non-Markovian electron dynamics in the microwave absorption of a two-dimensional electron system

We have studied the absorption of monochromatic microwave radiation in high-quality two-dimensional electron systems for the frequency span from 10 to 380 GHz using a bolometric method. For frequencies above 100 GHz the absorption exhibits an anomalous magnetic field dependence. Minima form at harmonics of the cyclotron resonance frequency. The results contrast previously reported data for other frequency ranges. Quasiclassical memory effects originating from the non-Markovian dynamics of electrons in a disorder potential containing short-range scatterers on top of a smooth potential background favorably account for the observed behavior.

Relief Restoration of Complicated form Objects by Monochromatic Microwave Radiation

Article demonstrates possibility of monochromatic radiation usage for relief restoration. There is a problem with restoration when scanned object is not flat and it is not parallel to the scanning plane. It was discovered that two-dimensional phase distribution could be applied for distance determination. It is reliable way to solve problems listed above. In conclusion offered methods allow monochromatic microwave radiation usage for screening system development.

Emission of monochromatic microwave radiation from a nonequilibrium condensation of excited magnons

The observation of monochromatic emission of radiation from a nonequilibrium Bose-Einstein-like condensate of magnons suggests the possibility of creating a monochromatic microwave generator pumped by incoherent broadband sources. The device would have a tunable emitted frequency as a function of the applied constant magnetic field. We present an analysis of the mechanisms of interaction between the condensate of magnons and the radiation field producing the super-radiant emission of photons. The conditions for the emergence of the super-radiance are described, as well as an analysis of its dependence on the thickness of the sample and the applied static magnetic field intensity.

Monochromatic microwave radiation from the system of strongly excited magnons

A conversion of a broadband microwave energy accumulated by a system of strongly excited magnons into a monochromatic microwave is demonstrated. The mechanism is based on recently discovered room-temperature Bose–Einstein condensation of nonequilibrium magnons. A realization of an electronically tunable microwave generator pumped by an incoherent broadband sources and the achievable linewidth of the monochromatic radiation are discussed.

Josephson Parameters of Bicrystal Junctions of a New Type Based on Metal Oxide Semiconductors

We have studied symmetric bicrystal Josephson junctions of a new type based on metal oxide superconductors in which the base planes are misoriented relative to the [100] direction by an angle within 22°–28°. These junctions exhibit record high values of the critical parameters at T = 77 K: the critical current density reaches I C = (2−5) × 105 A/cm2 and the characteristic voltage is V C = I C R N = 0.6−0.9 mV. The properties of the new junctions have been determined for the first time under the influence of monochromatic microwave radiation in the millimeter wavelength range and have been studied as functions of the magnetic field and temperature. The observed dependences of the critical current and the Shapiro step height on the electromagnetic field amplitude agree well with the theoretical predictions according to the resistive shunted junction model of the Josephson junction. The new junctions can be used in real superconducting devices operating at liquid nitrogen temperatures.

Selective interaction of a train of laser pulses with an aerosol medium

Stimulated scattering of light by oscillations of the shape of aerosol particles, excited resonantly by a train of high-intensity laser pulses, was detected and investigated. The excitation of natural oscillations of fog drops could be used to determine their size, to induce selective fragmentation, and to generate monochromatic microwave radiation in the presence of an external electric field.

Effect of High-Intensity Microwave Radiation on Optical Transitions of Atomic Hydrogen

Interaction of atomic systems with high intensity monochromatic microwave radiation leads to characteristic splittings of optical spectral lines