Optical properties of dual-core hollow waveguides

A new type of hollow glass waveguide has been fabricated that transmits radiation from visible to infrared wavelengths with low loss. The broadband transmission is achieved with a structure consisting of two distinct core regions; a silica annulus for transmission of wavelengths from 0.3 to 2.0 mu m and a hollow core for transmission from 2.0 to 12.0 mu m. Losses in the silica core at 633 nm are 0.3 dB/m. Losses in the 575-mu m bore hollow core at 10.6 mu m are 0.6 dB/m. Bending loss is negligible for radiation transmitted in the solid silica core, whereas the hollow guide loss exhibits a 1/R dependence. The dual-core waveguide can transmit broadband radiation, is lugged and flexible, and therefore, is a good candidate for medical or sensor applications. (C) 1996 Optical Society of America