Ultrahigh birefringent dual-slot silica photonic crystal fiber with ultralow nonlinearity

We proposed a new type of photonic crystal fiber (PCF) using two nano-scale elliptical air holes in the core region to control the property of birefringence and reduce the performance of nonlinearity simultaneously. Benefiting from the slot effect induced sub-wavelength mode confinement, the nonlinear coefficients of quasi-TE mode and quasi-TM mode at 1.55 μm are as low as 0.0143 W−1 m−1 and 0.02 W−1 m−1, respectively. More importantly, ultrahigh birefringence of 0.0293 is obtained at the wavelength of 1.55 μm thanks to the asymmetry of the fiber design. Owing to these excellent optical characteristics, the proposed dual-slot silica PCF will have great potential for high-speed telecom applications.