Metalens polarization detection technology in the C-band

Polarization, as one of the key degrees of freedom of light, offers additional information beyond intensity and wavelength, and plays a significant role in various applications such as target recognition, remote sensing, and quantum communication. In recent years, polarization detection technology in the infrared spectrum has attracted considerable attention. With the rapid advancement of metasurface technology, the miniaturization and integration of high-performance polarization detection devices have become a central focus of research. This paper presents a multifocal metalens structure based on geometric phase for polarization detection in the C-band. The proposed metalens has three foci, enabling the measurement of the full-Stokes parameters of incident polarized light. Despite the fact that current nanofabrication techniques have significantly enhanced the precision of metasurface manufacturing, small fabrication errors are still inevitable and typically remain within ±10 nm. Simulation results demonstrate that the polarization detection scheme remains robust and performs well even under such error conditions. This study provides novel design concepts and practical implementation approaches for achieving high-precision and high-stability infrared polarization detection devices.