Harmonic Analysis using Time-domain Simulation of Sinusoidally Time-varying Materials

It is shown how spectra of any harmonic order may be obtained from time-domain simulation of devices involving sinusoidal modulation of the constituent materials. The technique involves conducting multiple simulations in which the global phase of the modulating signals is progressively incremented. The ensuing simulation results are linearly combined to extract the harmonic order of interest. The technique is demonstrated via finite-different time-domain analysis of a space-time modulated surface which shows good agreement with theoretical calculations.