{'fraction_non_alphanumeric': 0.011235955056179775, 'fraction_numerical': 0.0, 'mean_word_length': 4.796747967479675, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Optical properties of Bragg fibres

The electrodynamic problem of propagation of light in a fibre with a cladding made of coaxial dielectric layers with alternating values of the refractive index is solved. The fibre core is a dielectric, in particular, air with the lowest permittivity in the fibre structure. A method is described for determining the structure of the multilayer cladding of a fibre having the minimal optical loss of the guided radiation for a particular mode. Losses in a fibre with a cladding with quasi-periodic layer thicknesses are calculated and the dispersion properties of the fibre are analysed. The analysis is performed for the lowest TE and TM modes and for the lowest hybrid mode.