Time Reversal in Subwavelength-Scaled Resonant Media: Beating the Diffraction Limit
Figure 6
(a) Unit cell of the SRR used in our numerical simulations and experiments. 4 basic SRR are used to design this cell in order to suppress the electric resonance. The SRR parameters are given in the text. (b) S parameters of a single cell obtained numerically using CST Microwave Studio. The S12 (transmission, solid blue curve) shows a sharp deep around 1.6 GHz while the S11 (return loss, dashed red curve) has a maximum at 1.6 GHz. Both curves indicated a sharp resonance of the SRR at 1.6 GHz. (c) Band structure of a plane of such SRRs arranged a square array of period 1.1 cm. The lower branch is the one that coupled evanescently to our source. Those modes are evanescent perpendicularly to the array since the band lies under the light line. The upper branch shows leaky modes (with good coupling to free space radiations and limited ) that are not interesting for our concept. Clearly the interesting subwavelength branch is dispersive which is crucial for our concept.
