Singularity expansion method for modeling of transients in dynamic open resonators and waveguides

Accurate analysis of electromagnetic fields evolution in a whispering gallery (WG) mode resonator with time dependent material parameters and in a circular waveguide with transient core is presented. The excited fields are described by means of a rigorous mathematical approach that is based on an analytical solution in the Laplace transform domain and accurate evaluation of residues at singular points of the obtained functions. Transient response of waveguide and resonator modes on a sole time switching material parameters as well as on a packet of pulses is considered.