Optical Tunneling through an Adjustable Liquid Metal Gap

First results were obtained with a scanning near-field optical microscope (SNOM) whose gap is filled with a droplet of a liquid metal alloy. The transmission of light through a metal layer may be considered a photon tunneling process. As to be expected on theoretical grounds, we find that the transmission vs. gap width varies on a scale of 5 to 10 mm, which is much more rapid than in any other NFO scheme. A correspondingly high lateral resolution may be anticipated. Successful operation of the device requires good wetting between the liquid metal, probe and sample.