Ultra-flattened nearly-zero dispersion and ultrahigh nonlinear slot silicon photonic crystal fibers with ultrahigh birefringence

•A new type of slot silicon crystal fiber is proposed.•Ultrahigh birefringence up to 0.0736 at 1.55μm is achieved.•The nonlinear coefficient of quasi-TE mode at 1.55μm is as high as 211.48W−1m−1.•Ultra-flattened dispersion of 0.49ps/(nmkm) for quasi-TE mode is also obtained.•The proposed PCF is suitable for all-optical polarization maintaining signal processing. A slot silicon photonic crystal fiber (PCF) is proposed to simultaneously achieve ultrahigh birefringence, large nonlinearity and ultra-flattened nearly-zero dispersion over a wide wavelength range. By taking advantage on the slot effect, ultrahigh birefringence up to 0.0736 and ultrahigh nonlinear coefficient up to 211.48W−1m−1 for quasi-TE mode can be obtained at the wavelength of 1.55μm. Moreover, ultra-flattened dispersion of 0.49ps/(nmkm) for quasi-TE mode can be achieved over a 180nm wavelength range with low dispersion slope of 1.85×10−3ps/(nm2km) at 1.55μm. Leveraging on these advantages, the proposed slot PCF has great potential for efficient all-optical signal processing applications.