Finite-Difference Complex-Frequency-Domain Method for Optical and Plasmonic Analyses

The finite-difference frequency-domain (FDFD) method is one of the most effective methods for obtaining the frequency responses of specific optical components, such as thin films and guided wave structures. This letter describes an efficient algorithm based on the FDFD method to perform optical and plasmonic analyses. Solutions to the Maxwell's equations in the complex-frequency-domain are obtained by the finite-difference scheme and are numerically transformed into the time domain using the fast inverse Laplace transform. Reliable time and frequency responses of electromagnetic waves can be obtained through a simple and fast procedure. Furthermore, the time increment and observation time can be selected freely, while maintaining the accuracy. These are verified by performing the electric near-field analyses of a metallic cylinder. The computational results by our method are compared with the exact solution and the finite-difference time-domain (FDTD) method. Some details of performing inverse Laplace transform are also discussed.