Controlled Changes in Spectra of Open Quasi-Optical Resonators

Abstract

Abstract-The efficiency of different ways for controlled changes of spectral characteristics of open electrodynamic resonant structures are studied and evaluated in the paper.

An FFT-Accelerated FDTD Scheme With Exact Absorbing Conditions for Characterizing Axially Symmetric Resonant Structures

“…Replacing the nonlocal EAC (16) on the virtual boundary L 1 with its local equivalent, EAC (25), yields a new estimate for the total computational cost:…”

“…Discretized EACs are integrated in the FDTD scheme in the following way: The EAC (18) on the virtual boundary L 2 is discretized and integrated in the FDTD scheme similarly; but one should remember that on this boundary U i (ρ, z, t) = 0 and U (ρ, z, t) = U s (ρ, z, t). (25) and (26) Here the discretization of the EAC (25) on the virtual boundary L 1 is derived first. The discretization of the EAC (26) on L 2 can be done in a similar way.…”

“…On L 1 the total field is a sum of the scattered field and the incident wave: U (ρ, z, t) = U s (ρ, z, t) + U i (ρ, z, t), and one should remember that (25) is formulated for the scattered field and the problem (45) is being solved for the total field. Approximating the derivatives in the left side of the auxiliary initial-boundary value problem in (25) with the central differences, and using the secondorder one-sided differences to approximate the derivatives in the righthand side, an explicit three-step scheme that updates the grid function…”

“…It should be noted here that the proposed method allows the transient analysis to be carried for long time intervals and can provide highly accurate and reliable numerical data pertinent to physical processes under resonant conditions [14,[23][24][25]. The proposed method is especially useful for accurate analysis of long-duration processes in resonant radiators and energy compressors with different types of storage units (e.g., waveguide and open resonators with metal, semitransparent, and frequency-selective mirrors) and switches (e.g., distributed grating-type switches, interference and resonant switches).…”

Evolution of Transient Electromagnetic Fields in Radially Inhomogeneous Nonstationary Medium

“…Projection of the set of Maxwell equations onto the Modal Basis permits to get the set of Evolutionary Equations. Actually, the MBM is one of varieties of the method of incomplete separation of variables [2,14] for more general statements of problems. MBM allows to exclude the dependence of functions on transversal coordinates from Maxwell Equations and leave the dependence of functions on longitudinal coordinate and time that permits to satisfy the causality principle in solution of the problem.…”