Broadband polarization beam splitter based on a negative refractive lithium niobate photonic crystal slab

Using a lithium niobate(LN) material, we propose a broadband polarization beam splitter(PBS) with high efficiency by employing a negative refractive photonic crystal(PhC) wedge slab with an angle of 60°. It can split the incident light into two parts at about 90° with TE and TM polarizations. The transmissions of polarized light for an LN-based PBS are more than 80% with a broad angle and wavelength bandwidth of 8° and 70 nm at1.55 ^rni, while with a Si-based PhC, no PBS with high efficiency can be realized for the relatively lower transmission of TM output light.