Significant enhancement of evanescent spatial harmonics inside the slabs of media with extreme optical anisotropy is revealed. This phenomenon results from the pumping of standing waves and has the feature of being weakly sensitive to the material lo
sses. Such characteristics may enable subwavelength imaging at considerable distances away from the objects.
Evanescent wave amplification is observed, for the first time to our knowledge, inside a half-wavelength-thick wire medium slab used for subwavelength imaging. The wire medium is analyzed using both a spatially dispersive finite-difference time-domai
n (FDTD) method and a full-wave commercial electromagnetic simulator CST Microwave Studio. In this work we demonstrate that subwavelength details of a source placed at a distance of one-tenth of a wavelength from a wire medium slab can be detected inside the slab with a resolution of approximately one-tenth of a wavelength in spite of the fact that they cannot be resolved at the front interface of the device, due to the rapid decay of evanescent spatial harmonics in free space.
This is a comment on Guiding, Focusing, and Sensing on the Subwavelength Scale Using Metallic Wire Arrays by G. Shvets, S. Trendafilov, J. B. Pendry and A. Sarychev published in Phys. Rev. Lett. 99, 053903 (2007), which demonstrates that the endoscop
e proposed in the letter does not demonstrate satisfactory subwavelength imaging performance.
