Large Mode Area Single Mode Fiber with a Twisted Polygon-Shaped Core

We present numerical studies on twisted polygon-shaped core fibers for achieving single mode operation with a large mode area propagation in this paper. These large mode area fibers can achieve single mode operation due to twisting-induced high losses to higher order modes and coupling higher order modes with leaky modes. A tail-like profile will appear in higher order modes when they couple with leaky modes, and the tail-like profile also indicates that these modes carry angular momentum. Numerical simulations show that twisted octagon-shaped core fiber with a core diameter of 80 mu m can obtain first higher order mode losses larger than 19 dB/m while maintaining fundamental mode losses at about 0.15 dB/m. In the case of twisted heptagon-shaped core, an 80 mu m diameter fiber design exists with more than 17 dB/m first higher order modes propagation losses and less than 0.14 dB/m fundamental mode losses.