The above simulation is for a single cycle Terahertz pulse generated inside a silicon lens and propagating forward in time. The simulation method is Finite Difference Time Domain (FDTD) implemented through Matlab. This propagates the electric field by solving Maxwell's equations in small time increments over a very fine spatial grid. Notice how the field couples to the strongly curved surface of the lens and seems to creep along the surface before the pulse detaches from the lens. This is known, surprisingly, as the creeping wave (or surface wave) and is evident when electromagnetic radiation interacts with objects that are on the same size as a wavelength.
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