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Two geometries of the superheterodyne amplification of electromagnetic pulses of the optical range are investigated theoretically in the waveguides on the base of n-GaN and n-InN films. In the first geometry the pump optical wave moves oppositely to the signal wave, in the second geometry all interacting waves move in the same direction. This amplification is the transfer of the amplification of the...
It is investigated theoretically the excitation of short monopulses of space charge waves with a wide spectrum in THz range due to the negative differential conductivity in nitride films of submicron thicknesses. In n-GaN and n-InN films it is possible to generate the pulses of ≤5 ps durations of high values of the electric field. The influence of the nonlocal dependence of the average electron velocity...
The nonlinear properties in THz range of 3D electron gas in narrow-gap n-InSb semiconductor and 2D one in graphene are investigated theoretically. The nonlinear dependencies of the density of electric current on the applied electric field have been computed from the kinetic approach under finite temperatures. A comparison has been done with the analytic dependencies obtained when an influence of the...
It is investigated the frequency multiplication of terahertz electromagnetic radiation in dielectric waveguides on the base of the crystalline paraelectric SrTiO3 at the temperatures 77 K when a bias electric field is applied. The frequency dispersion and the transverse width of the waves affect the generation of higher harmonics. It is possible to select the certain numbers of higher harmonics due...
The giant resonant excitation of the second harmonic of THz radiation in planar "dielectric — graphene — dielectric…" metamaterial is investigated. Oblique incidence of sand p-polarized first harmonics is considered, using kinetic and hydrodynamic approaches. The reflection into the second harmonic reaches the values of 0.1 for intensities and more.
It is investigated the generation of terahertz radiation with using the oscillations of crystalline lattices. The numerical simulations are presented of the instability of the optical phonons of THz range in the semiconductor structures with quantum wells under the drift of 2D electron gas. The main obstacle for the realization of this instability is the heating of the electron gas. Therefore the...
It is investigated the modulation instability of transversely bounded long THz pulses in waveguides on the base of the paraelectric SrTiO3 at the temperatures 77 K. The cubic nonlinearity and the frequency dispersion correspond to existence of envelope solitons and the modulation instability of long input pulses, whereas in the transverse direction the instability is absent. There exists a possibility...
We develop farther our “three-level” approach to graphene metamaterials including “metamaterial treatment” of 2D beams of electron (BE) in graphene with 2D inhomogeneous and nonlinear electromagnetic waves in graphene-dielecric multlayered structres. A possibility of resonant behaviour of the components of the electron disrribution function in 2D “diffraction grating”, with 1D periodicity along a...
Starting from the kinetic expression of 2D nonlinear electric current in the graphene, the new equation is derived, to simulate nonlinear THz electromagnetic wave propagation through layered graphene - dielectric lossy structures. A possibility of nonlinear switching of short THz pulses in multilayer structure is shown.
We study the propagation of electromagnetic waves through a slab of graphene metamaterial composed of the layers of graphene separated by dielectric slabs. Starting from the kinetic expression for two-dimensional electric current in graphene, we derive a novel equation describing the nonlinear propagation of terahertz electromagnetic pulses through the layered graphene-dielectric structure in the...
Tunable, nonlinear and active metamaterials are discussed, as a basis of optical instrumentation and signal processing such as filters, birefringent devices, lenses etc. The new method for modeling nonlinear field and energy concentrators is reported, which includes the combination of the new version of complex geometrical optics (CGO) and full-wave nonlinear electromagnetic solution (FWNES) used...
A new method for modeling layered media with layers of active bi-anisotropic metamaterial and propagation of nonlinear waves is developed. Numerical estimations are done for backward wave amplification in the active media
A possibility of formation of the nonlinear structures under the parametric interaction of nonlinear pulses of the backward volume magnetostatic waves (BVMSWs) in the ferrite film (FF) is shown
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