Plasmonic endoscope: guiding, magnifying and focusing of infrared radiation on a nanoscale

摘要

It has recently been shown that tapered arrays of thin metallic wires can guide and manipulate electromagnetic fields on the sub-wavelength spatial scale. Our computations demonstrate that two types of nanoscale imaging applications using terahertz and mid-infrared waves are enabled: image magnification, where the tapered wire array acts as a multi-pixel endoscope by capturing an electromagnetic field profile created by deeply sub-wavelength objects at the endoscope's tip and magnifying it for observation, and radiation focusing, where the image of a large mask at the endoscope's base is projected onto a much smaller image at the tip. The most important result of this work is the demonstration of a new computational technique that enables extracting TE, TM and TEM modes from a full 3-D electromagnetic simulation. Through extraction of the TEM electric field from the total electric field we show that the physical mechanism of the image propagation along the guiding structure is indeed the TEM modes of the multiconductor array.