Space-multiplexing Fiber Meta-tip for Efficient Polarization Conversion in Near-infrared Regime

In this paper, a four-channel space-multiplexing fiber meta-tip is successfully realized. The fiber meta-tip is implemented by integration of a polarization conversion metasurface and a four-channel fiber-tip. The designed a-Si metasurface achieves linear-to-circular polarization conversion at wavelength of 833 nm to 868 nm. The ellipticity of transmitted light is designed to be 0.98, and measured up to 0.951 at 852 nm. In addition, the ellipticity of the four-channel fiber output is measured as 0.918, 0.917, 0.914, and 0.897. Using the integration approach proposed in this paper, the four-channel space-multiplexing fiber meta-tip can be further extended to more channels.