Novel Passive Polarization Rotator Based on Spiral Photonic Crystal Fiber

In this letter, a novel design of a passive ultra-compact polarization rotator based on soft glass equiangular spiral photonic crystal fiber (ES-PCF) is proposed and analyzed using full vectorial finite difference approaches. The suggested ES-PCF has eight arms with a central elliptical air hole, which can be shifted in $x$ and $y$ directions to achieve complete polarization conversion. In addition, the major axis of the elliptical hole is rotated by 45 $^{\circ}$ , which offers 99% polarization conversion ratio with ultra-compact device length of 96 $\mu{\rm m}$ . It is also evident from the numerical results that the polarization rotation would be more than 98% over the 1.5–1.6 $\mu{\rm m}$ wavelength range.