A complementary study to "Hybrid hollow core fibers with embedded wires as THz waveguides" and "Two-wire terahertz fibers with porous dielectric support:" comment

In a recent paper, Anthony et al. [Opt. Express 21, 2903 ( 2013)] demonstrated broadband terahertz pulse propagation through the hollow core fibers with two embedded Indium wires. In another paper by A. Markov et al. [Opt. Express 21, 12728 ( 2013)], we proposed a plasmonic THz fiber featuring two metallic wires held in place by the porous dielectric cladding functioning as a mechanical support. Although the cross sections of the two waveguides look very similar, we were surprised to find that the guidance mechanisms for these two waveguides are quite different. In fact, waveguide considered by A. Markov et al. was guiding a plasmonic mode, while the waveguide presented by Anthony et al. was guiding a dielectric waveguide-like mode. Finally, we have realized that by reducing the waveguide dimensions by a factor of similar to 10-20 one can transition from the dielectric waveguide guidance as it is demonstrated by Anthony et al. to plasmonic guidance as reported in A. Markov et al. Therefore, we conclude that both waveguide are essentially identical, while their guidance mechanism changes as a function of the waveguide overall size. (C) 2013 Optical Society of America