High birefringent rectangular-lattice photonic crystal fibers with low confinement loss employing different sizes of elliptical air holes in the cladding and the core

Based on the full-vector finite element method with anisotropic perfectly matched layers, modal birefringence and confinement loss for the fundamental mode in rectangular-lattice photonic crystal fibers with different sizes of elliptical air holes in the cladding and the core are investigated numerically. The results show that the modal birefringence in this proposed photonic crystal fibers can be up to 5.64 × 10−2 at the wavelength of 1.55 μm. Moreover, when the birefringence is higher than 4 × 10−2, the confinement loss of x-polarized mode can be kept less than 0.005 dB/km at 1.55 μm. It means that the tradeoff between the high birefringence and the low confinement loss is overcome.

► Ultrahigh birefringence (5.64 × 10−2) can be achieved at 1.55 μm.
► The confinement loss of x-polarized mode can be kept less than 0.005 dB/km at 1.55 μm.
► The tradeoff between the high birefringence and the low loss can be overcome.
► The proposed PCFs can be used as low confinement loss and high birefringence polarization maintaining fiber.