Highly multi-mode anti-resonant hollow core fibres

We report the characterisation of anti-resonant hollow core optical fibres guiding at least 50 spatial modes in the infrared. Their propagation losses were measured to be between 0.1 and 0.2 dB/m from 1000 to 1500 nm wavelength, with bend losses of less than 3 dB/turn for bend radii of 7.5 cm despite core radii greater than 60 times the guided wavelengths.