Anti-torsion solid-core polarization-maintaining photonic crystal fiber based on anisotropy of stress distribution

An anti-torsion solid-core polarization-maintaining photonic crystal fiber based on anisotropy of stress distribution, the photonic crystal fiber comprising a core and a cladding that includes an inner layer arranged around the core and an outer layer between the inner layer and an outer wall of the cladding, wherein

• the inner layer has multiple layers of first air holes, each having a first diameter, arranged for constructing optical properties and two micron-size air holes arranged along an x-axis extending through a center of the inner layer for guaranteeing birefringence in the fiber, wherein the micron-size air holes are each larger than each of the first air holes;
• the outer layer has multiple layers of second air holes, each having a second diameter, arranged around a y-axis, wherein the y-axis is perpendicular to the x-axis, wherein the multiple layers of second air holes are arranged to be evenly distributed and enclosed in two equilateral triangles, each with one side parallel to the x-axis and corresponding to an inner border or an outer border of the outer layer of the cladding;
• the second diameter is different from the first diameter;
• the inner layer and the outer layer as a whole are symmetric with respect to the x-axis and the y-axis as a whole;
• and
• the multiple layers of second air holes are configured in a way as to cause the bending stiffness of the photonic crystal fiber along the x-axis to be different from the bending stiffness along the y-axis.