Design of Broadband Single Fundamental Mode Hollow Core Bragg Fibre

The condition of the single fundamental mode (HE₁₁) transmission in hollow core Bragg fibres is investigated theoretically by the transfer matrix method. The influences of core size and cladding parameters on the single HE₁₁ mode bandwidth are analysed, showing that the maximal bandwidth is more sensitive to the core size than the cladding. The numerical results show that sufficiently broad bandwidth of single HE₁₁ mode transmission can be achieved by proper fibre design. A simple and fast method based on improved
hollow metal waveguide model is proposed to optimize fibre structure parameters for the maximal single HE₁₁ mode bandwidth.