Optimal design of sub-wavelength metal rectangular gratings for polarizing beam splitter based on effective medium theory

A novel optimal design of sub-wavelength metal rectangulargratings for the polarizing beam splitter (PBS) is proposed. Themethod is based on effective medium theory and the method ofdesigning single layer antireflection coating. The polarizationperformance of PBS is discussed by rigorous couple-wave analysis(RCWA) method at a wavelength of 1550~nm. The result shows thatsub-wavelength metal rectangular grating is characterized by a highreflectivity, like metal films for TE polarization, and hightransmissivity, like dielectric films for TM polarization. Theoptimal design accords well with the results simulated by RCWAmethod.