Infrared dual-band multi-focus full Stokes metalens for polarization detection

Infrared polarization detection has attracted wide applications in military and civilian fields by demonstrating more accurate target detection and identification capabilities due to more dimensional target information. A multifocal metalens for simultaneous detection of the polarization state of incident light at dual wavelengths is proposed based on the independent control of orthogonally polarized light. When light is incident at different wavelengths, the metalens array splits and focuses the light on three different polarization bases to form six focal points with various positions. When the incident light with varying states of polarization of dual wavelengths to be detected passes through the substrate and reaches the metalens array, the incident light detected in each wavelength forms six focal points at different positions of the focal plane of the metalens. The Stokes parameters are calculated based on the intensities of the six polarization components in the same focal plane to determine the polarization data of the azimuthal and elliptic angles of the incident light detected in each wavelength. In addition, the theoretical Stokes parameters of incident light with different polarization states at two wavelengths are compared with the reconstructed Stokes parameters, proving our method's validity. The device can directly examine the polarization state of the incident light in mid-wave infrared and long-wave infrared, significantly simplifying the polarization detection system.