Efficient spin beam splitter based on PB metasurfaces

We propose a spin beam splitter based on dielectric metasurfaces, designed according to the PB phase. This structure consists of elliptical nanocolumns made from GaAs material, with a quartz substrate. The spectral intensity consistently exceeds a threshold of 0.8 when exposed to right-handed circular polarization (RCP) and left-handed circular polarization (LCP) within the wavelength range of 930 to 1000nm. Besides, the spectral angle can be adjusted, varying from 14.97° to 16.12°, allowing for precise control over these optical properties within the specified parameters. When the working wavelength is 944nm, the spectral intensity is as high as 0.936 and the beam splitter angle is 15.5°. Under linearly polarized (LP) incident light, the beam splitter can divide the light into RCP and LCP beams, and both of them can maintain high transmission intensity close to 0.5. In addition, the effects of wavelength and oblique incidence on the beam splitting performance of the device are studied. By changing the incident angle from 10° to 40°, we observed a important influence on the intensity and angle of the beam splitter. The engineered beam splitter could serve major functions in the development of photonic devices moving forward and may be instrumental in domains such as quantum computing, photonics, and information processing.