Absolutely single polarization photonic crystal fiber based on a structure of sub-wavelength hole pitch

An absolutely single polarization photonic crystal fiber (ASP-PCF) with periodic structure of sub-wavelength hole pitch is proposed. Circular air holes and elliptical air holes with diameters smaller than the operation wavelength are employed in the fiber cladding area and the fiber core area, respectively. Calculation results show that both ultra-high birefringence and ASP operation are achieved over a large wavelength range covering the fiber optical communication window from 1300 nm to 1600 nm for the proposed ASP-PCF. The ASP operation bandwidth can be further enlarged based on the optimized designs.