Giant optical transmission of a subwavelength slit optimized using the magnetic field phase.
In this Letter, we show that the energy equivalent to that incident on a 4.7 microm wide strip can be squeezed through a 50 nm wide slit in a metal film surrounded by grooves. This corresponds to a transmission efficiency of 9400%, which can be even further enhanced by increasing the number of grooves. We use the phase of the magnetic field to explain that the ideal slit-to-groove distance is just over half the plasmon wavelength. In addition, we also optimize the groove depth and width. Such optimized transmission enhancement is very important for near-field devices.
Optics Research Group, Delft University of Technology, 2628CJ Delft, The Netherlands.
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Janssen
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Urbach
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't Hooft