We analytically describe light transmission through a single subwavelength slit in a thin perfect electric conductor screen for the incident polarization being perpendicular to the slit, and derive simple, yet accurate, expressions for the average electric field in the slit and the transmission efficiency. The analytic results are consistent with full-wave numerical calculations and demonstrate that slits of widths similar to 100 nm in real metals may feature nonresonant (i.e., broadband) field enhancements of similar to 100 and transmission efficiency of similar to 10 at infrared or terahertz frequencies, with the associated metasurface-like array of slits becoming transparent to the incident light. (C) 2016 Optical Society of America
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