Nano-coax cable

This was a good idea just waiting to happen:

“Subwavelength waveguide for visible light”: J. Rybczynski et al., Applied Physics Letters 90, 021104 (2006).

The authors demonstrate transmission of visible light through metallic coaxial nanostructures many wavelengths in length, with coaxial electrode spacing much less than a wavelength. Since the light frequency is well below the plasma resonance in the metal of the electrodes, the propagating mode reduces to the well-known transverse electromagnetic mode of a coaxial waveguide. They have thus achieved a faithful analog of the conventional coaxial cable for visible light.

Or, in simpler terms, a coaxial cable made from a carbon nanotube (CNT)! Here’s a picture that nicely summarizes the ‘device’:

The CNT is shown in (a) and is grown on the glass substrate using plasma-enhanced chemical vapor deposition (CVD); it is then coated with aluminum oxide (b) and chromium (c) by sputtering. To have an open end, the authors used a mechanical ‘polishing’ technique.

The end result? Nanoscale coaxial cables that are able to “strongly transmit light in the entire visible frequency range, without frequency cut-off… the propagation is essentially via the conventional TEM mode of a common coaxial cable.