Fig. 1
From: Hollow-core conjoined-tube negative-curvature fibre with ultralow loss

Demonstration of an ultralow-loss broadband CTF. a Scanning electron microscope (SEM) image of the fabricated CTF with outer diameter of 295 µm. The yellow numbers label the five dielectric layers in the cladding. b Measured transmission spectra of the 330 m (black) and 5 m (blue) long CTF under the same launching condition. c Measured cut-back loss (black) and simulated loss (grey, including both CL and SSL). The spectral extension of the optical telecommunication O, E, S, C and L bands are also shown for comparison