Hollow Waveguides

Abstract

Hollow-core waveguides (HCWs) are comprised of a central hole surrounded by a highly reflective inner wall. The core can be filled with air, inert gas, liquid, or vacuum, allowing these waveguides to transmit a broad range of wavelengths with low attenuation. HCWs are of particular interest for the transmission of infrared (IR) to THz radiation, where it is otherwise difficult to find materials that have the optical, thermal, and mechanical properties required for use in solid-core optical fibers. Therefore, IR-transmitting hollow waveguides can be an attractive alternative to solid-core IR fibers. Hollow waveguides can be made from plastic, metal, or glass tubes that have highly reflective coatings deposited on the inside surface. These waveguides have losses as low as 0.1 dB/m at 10.6 mm and may be bent to radii less than 5 cm. For use in high-power laser delivery applications, the waveguides have shown to be capable of transmitting up to 3 kW of CO2 laser power. They are also finding uses in both temperature and chemical fiber sensor applications. This chapter will give a brief review about the progress in hollow waveguide technology with emphasis on the available hollow waveguides that have been developed. © Springer International Publishing Switzerland 2014.