A novel highly birefringent photonic crystal fiber (PCF) with hybrid cladding is proposed. In this hybrid structural PCF, some air holes of the cladding are selectively filled with high refractive index material. The increased birefringence mainly results from that the symmetry is destroyed further in the designed PCF. The birefringence is theoretically investigated with variant structural parameters and refractive index of the filled material. The plane wave expansion method (PWE) and full-vector finite-element method (FEM) are respectively employed to investigate the optical properties of the proposed PCF. The numerical results show that the designed PCF can provide high birefringence and be well tuned by the structural parameters and refractive index of the filled material. It can be used as all-fiber polarization controllers and highly sensitive sensors.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.