26 km-long polarisation-maintaining optical fibre

The letter describes the development of a long-length and large-diameter preform for polarisation-maintaining optical fibres. The preform was 470 mm in length and 48 mm in diameter. As a result, a 26 km-long PANDA fibre is developed. This fibre achieves crosstalk of ¿22 dB, corresponding to h = 2.4 × 10-7m-1 and a transmission loss of 0.3 dB/km at a wavelength of 1.56 ¿m. These fibres will be useful for future high-speed and medium-span coherent optical communications.