Development and study of Bragg fibres with a large mode field and low optical losses

A silica Bragg fibre with optical losses lower than 10 dB km^-1 is fabricated for the first time. The Bragg fibre manufactured by the MCVD method is intended for operation at a wavelength of 1.06 μm and has the mode-spot diameter 18.5 μm (the mode-spot area is 270 μm²). The fibre is considerably less sensitive to bending than step-index fibres and microstructure fibres with the same mode-spot size. The possibility of fabricating a Bragg fibre with the record mode-spot area (530 μm² at the operating wavelength of 855 nm) for all-silica fibres is demonstrated.