High-Flexible Single-Polarization Single-Mode Photonic-Crystal Fibre

We propose a new type of high flexible single-polarization single-mode (SPSM) photonic crystal fibre (PCF). Numerical analysis indicates that the SPSM PCF proposed guides only one polarization mode over a wavelength band broader than the conventional SPSM fibres. The position and the bandwidth of the single polarization mode region depend flexibly on the structure parameters such as the hole diameters d 1 and d 2 and the hole pitch Λ of the SPSM PCFs. A 200-nm SPSM region can be obtained for the SPSM PCF with Λ = 2.55 μm, d 1 /Λ = 0.3 and d 2 /Λ = 0.833 and the modal birefringence at the wavelength 1.31 μm can reach 1.8 × 10 −3 .