Optical properties of a Moire-lattice photonic crystal fiber with controllable magic angle

Inspired by the unique electrical properties of bilayer-twisted graphene with moire superlattice, the light manipulation using photonic moire structures has attracted tremendous research interest. In this paper, the moire-lattice arrangement is introduced into the cladding of fiber to construct the moire-lattice photonic crystal fiber (PCF) with two identical triangular-lattice or square-lattice layers of air holes rotated by a certain angle. The optical properties of the moire-lattice PCF are studied in detail by varying the rotation angle with regards to the dispersion, effective mode field area, nonlinear coefficient and bending loss. Numerical results show that the optical properties of guiding mode can be flexibly regulated and optimized by the rotation angle. Moreover, the fiber can maintain single-mode transmission and low bending loss at different rotation angles. This moire-lattice PCF provides a new way of regulating the structure for optimizing the fiber properties and offers a guidance for engineering moire-lattice fiber devices.