Study of electromagnetic wave transmission due to temporal modulation of permittivity in a spatially confined region of a medium

The paper investigates the scattering caused by a temporally modulated permittivity in a spatially confined region of a medium due to an external source. A realistic model of temporal variation of electrical permittivity in an arbitrarily bounded over space, causal medium—compliant with the Kramer-Kronig relation—has been adopted to study the transmission across such a perturbed region. The transmission through the modulated region is compared with the corresponding results obtained from an equivalent Fabry-Pérot etalon to gauge the difference between the resulting structural and temporal scattering. The temporal modulation was found to induce dispersive behavior in a non-dispersive medium. Additionally, it is observed that an incident Gaussian pulse on the modulated region causes the medium to transmit pulses for a longer duration than an equivalent non-dispersive slab.