A new time-domain asymptotic solution for transient WG mode radiation fields excited by a pulse source

We have derived the new time-domain (TD) asymptotic solution for the transient whispering gallery (WG) mode radiation fields. By comparing with the reference solution, we have confirmed the validity of the new TD asymptotic solution. We have shown that the proposed TD asymptotic solution improves the accuracy compared with the conventional asymptotic solution in the early time and late time responses. It is also clarified that the TD asymptotic solution derived here is easy to understand the radiation and diffraction phenomena of the transient WG mode radiation.