Modeling of the twist-induced effect in circular photonic crystal fiber transmitting orbital angular momentum modes

Abstract

The influence of twist-induced effect on the performance of anisotropic optical fiber is investigated theoretically and numerically. First, we study the light propagation in the twisted optical fiber with twist-induced mechanical stress using the analytical solution of the vector wave equation. Second, under the twist-induced effect, the twisted orbital angular momentum (OAM) fiber simulation model is established using circular photonic crystal fiber (PCF) as an example. Compared with the ordinary ring fiber, PCF has higher refractive index contrast without doping, larger fiber bandwidth, better mode quality, lower confinement loss, and larger manufacturing tolerance. Moreover, we analyze the mode quality and transmission characteristics of the twisted OAM fiber. The results show that the twist-induced effect on the high-order vector mode is different from that of the fundamental mode. The twist-induced effect introduces coupling in the high-order vector mode and changes the structure of the eigenmodes under different torsional effects. These superior optical properties are advantageous to twisted OAM fibers for stable data transmission in large-capacity and long-distance optical fiber communication systems.