High-order operating mode selection using second-order bandgap in THz Bragg fiber

This paper demonstrates a novel design technique for single-TE₀₁-mode Bragg fiber using a second-order bandgap achieving signal propagation loss less than 1.2 dB/m from 0.85 THz to 1.15 THz. The TE₀₁ mode intrinsically has a null point in the electric field close to the interface region between the core and the cladding. This makes the TE₀₁ mode preferable to other modes since it shows low signal propagation loss and low electromagnetic interference from cladding defects. Bragg iîber can exhibit a strong mode selectivity as a result of modal-iîltering effects. A large loss discrimination between the desired TE01 mode and competing modes can be designed by appropriately tailoring the photonic bandgap.