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 improvedhollow metal waveguide model is proposed to optimize fibre structure parameters for the maximal single HE11 mode bandwidth.