Electromagnetic fluctuations in anisotropic dielectric crystals

Landau and Lifschitz's theory of electromagnetic (EM) fluctuations in dielectric media is applied to anisotropic dielectric crystals. In the limit of zero damping the spectra of the autocorrelation functions of the EM-field in unaxial crystals are calculated. With the aid of these spectra a generalized Planck's law of radiation is reported.     

Probe fluctuations in a phase-conjugate resonator

Analytical expression are derived for the conjugated and specular reflections from a phase-conjugate resonator probed by a fluctuating beam. Phase fluctuations are described by a diffusion model. The results, demonstrating a strong dependence on the coherence time, are shown to coincide with expressions based on abrupt phase changes. Amplitude fluctuations, represented by a sudden-jump model, are shown to play almost no role in the behaviour of the resonator.     

Synchronization of wakefield modes in the dielectric resonator

Multimode excitation of a wakefield in a planar dielectric resonator by a regular sequence of relativistic electron bunches is studied analytically and numerically. It is shown that, if the wakefield being excited consists of a large number of radial modes, the fields from the regular sequence of the bunches add together. Conditions under which this sequence provides synchronization of the dielectric resonator modes are found. Acceleration of a test bunch in the wakefield of the bunch sequence is studied.     

Polaron self-energy in a dielectric slab

The lowering of the ground state energy of an electron below the bottom of the conduction band by virtue of its interaction with the longitudinal optical phonons is calculated as a function of the dielectric's thickness. The bulk result, —α$\text{h}\text{?}$;ω, is found as the thickness approaches infinity.     

Whispering-gallery modes in a barrel-shaped dielectric resonator

We experimentally study a new type of resonator, namely, a barrel-shaped dielectric resonator with whispering-gallery modes which is formed by the cutting dielectric hemisphere. Compared with a hemispherical dielectric resonator, the E type oscillation spectrum of such a resonator is rarefied with respect to the azimuthal index. Comparative analysis of the electromagnetic characteristics of the barrel-shaped dielectric resonator and half-disk dielectric resonators shows that the radiation losses of the mode energy from the spherical surface are smaller than those from the cylindrical surface. This fact stimulates the high values of the internal Q-factor of modes of the barrel-shaped dielectric resonator. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 12, pp. 1041–1048, December 2005.     

Quasioptical open resonator with dielectric filling

Radiophysics and Electronics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 31, No. 5, pp. 591–599, May, 1988.     

Vacuum lightcone fluctuations in a dielectric

A model for observable effects of time modulated electromagnetic vacuum fluctuations is presented. The model involves a probe pulse which traverses a slab of nonlinear optical material with a nonzero second order polarizability. We argue that the pulse interacts with the ambient vacuum fluctuations of other modes of the quantized electric field, and these vacuum fluctuations cause variations in the flight time of the pulse through the material. The geometry of the slab of material defines a sampling function for the quantized electric field, which in turn determines that vacuum modes whose wavelengths are of the order of the thickness of the slab give the dominant contribution. Some numerical estimates are made, which indicate that fractional fluctuations in flight time of the order of 10⁻⁸$10^{-8}$ are possible in realistic situations. The model presented here is both an illustration of a physical effect of vacuum fluctuations occurring in a finite interval of time, and an analog model for the lightcone fluctuations predicted by quantum gravity.     

Open resonator for measuring high-losses dielectric

The three-mirror open resonator (OR) with the prism of total-internal-reflection (TIR) for measuring dielectric constants of high-losses dielectrics is presented. The calculations of the resonator characteristics in approximation of wave beams have been carried out. Parameters of the system such as coupling gap value and dielectric constant of the prism which provide the high sensitivity of experiment were determined.     

The input impedance of the dielectric resonator antenna

Dielectric cylinders of very high permittivity have been used in the past as resonant cavities, but since the structure is not enclosed by metallic walls, electromagnetic fields do exist beyond the geometrical boundaries of the structure and part of the power is radiated. Through the proper choice of geometry and permittivity this radiation can become the dominant feature of the structure and become an efficient antenna for use at millimeter wave frequencies. Both experimental and theoretical investigations of a variety of these dielectric resonator antennas have been undertaken. In particular, the input impedance of a probe-fed cylindrical structure was examined in detail and a comparison of theoretical and experimental results was made.     

35 GHz dielectric resonator stabilised gunn oscillator

A 35 GHz dielectric resonator oscillator(DRO) using GaAs Gunn diode in microstrip configuration has been designed and developed. The oscillator, with an integral waveguide-to-microstrip transition, delivered an output greater than 18 dBm. Phase noise of the oscillator is found to be better than –80 dBc/Hz at 100 KHz away from the carrier. A frequency drift of about ±25 MHz has been observed over the temperature range from –10 °C to 50 °C.     

Low temperature behaviour of the blackbody radiation energy in the infinite slab resonator

The total radiation energy between two infinite extended metallic plates with distance L is studied. A low temperature representation of the energy is calculated the leading term of which is proportional to T³.For L·;T < 0.1 cmK this term is the dominant one and all other contributions may be neglected.     

Pulse propagation in a nonlinear dielectric slab waveguide

The evolution of an optical pulse in a single-mode, step index dielectric slab waveguide which is characterized by an intensity dependent dielectric function in the core and cladding regions is treated by means of differential equation techniques. A cubic order non-linearity is considered. The electromagnetic field distribution in the slab waveguide region satisfies a non-linear wave equation. This field can be represented in terms of even TE guided modes with a slowly varying envelope amplitude function.Then using the well known approximation, based on the slowly varying character of the amplitude function, a non linear partial differential equation is obtained for the amplitude function. As the coefficients of this equation depend on the distance across the transverse direction X, an averaging technique over x is applied to reduce the nonlinear partial differential equation into a form that is easily transformed to the so-called non-linear Scroedinger differential equation.This equation is then attacked by means of the well known Inverse Scattering method in the case of reflection less potentials. The single and double soliton solutions are obtained explicitly for a single-mode slab waveguide. Finally numerical results are presented in the time domain.     

Spherical dielectric resonator in near zone of waveguide radiator

The results of an experimental study of the electric field near a dielectric resonance sphere located at the open end of a rectangular waveguide or in the near zone are presented. The field distributions at the resonance frequencies of reflection and transmission and far from resonance are studied. The results are compared with the case of an unloaded waveguide radiator.Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 5, pp. 451–457, May, 1992.     

Nonlinear waves guided by a dielectric slab

An exact solution of Maxwell's equations is found for TM-polarized nonlinear guided waves which are guided by a linear dielectric slab embedded between two nonlinear uniaxial media. Additional waves in comparison with the linear case arise. Some of these waves have no counterpart in linear systems. Similarities and differences with respect to TE-polarized nonlinear guided waves are pointed out.     

Nonlinear waves guided by a dielectric slab

We consider dispersion relations and field structure of TE-polarized guided waves travelling along an asymmetric dielectric slab surrounded by two different nonlinear media. For a given configuration there are four types of guided waves. Three of this four types possess at least one field maximum outside the slab region and have no counterpart in linear waveguide optics. The solutions of the dispersion relations depend now on an additional parameter making them more flexible with respect to the linear limit.     

Theoretical analysis of whispering-gallery mode ring dielectric resonator

A new type of whispering-gallery mode ring dielectric resonators are first proposed. Theoretical analysis and a method for determination of the resonant frequencies is presented by the mode matching method. The numerical results show good agreement with theoretical analysis.