Subgridding in the finite-difference time-domain method for simulating the interaction of terahertz radiation with metal

Simulating the interaction of electromagnetic terahertz radiation with metals poses difficulties not encountered in the optical regime. Owing to a penetration depth small compared to the wavelength, such simulations in the terahertz frequency range require large discretization volumes with very small grid spacings. We present a unique subgridding scheme that accurately describes this interaction while keeping computational costs minimal. Bidirectional coupling between grids allows for the complete integration of subdomains into the simulation volume. Implementation in one and two dimensions is demonstrated, and a comparison with theoretical and experimental results [Opt. Express 15, 6552 (2007)] [Phys. Rev. B 69, 155427 (2004)] is given. Using our technique, we are able to accurately simulate plasmonic effects in terahertz experiments for the first time. (C) 2008 Optical Society of America.