Abstract
Mid-wavelength infrared (MWIR) full-Stokes detection is critically important for diverse applications. Although metasurfaces enable compact MWIR full-Stokes polarimetry, two major challenges remain: the high absorption loss of plasmonic metasurfaces, and the general reliance on external sensors for complete Stokes measurement. This paper proposes an on-chip integrated MWIR full-Stokes detection scheme based on germanium (Ge) metasurfaces and mercury cadmium telluride (HgCdTe) detectors. Six-channel dielectric Ge metasurfaces are designed to selectively transmit specific polarization states. Numerical simulations and particle swarm optimization (PSO) are used to optimize the geometry. The design shows a linear extinction ratio (ER) of 48 dB at 4 μm and a circular dichroism (CD) of about 0.98. The chiral channel exhibits a full width at half maximum (FWHM) of 0.74 μm, while the linear channel maintains an ER above 24 dB over a 300 nm bandwidth. Full-Stokes parameters are reconstructed from six-channel transmittances using a calibration matrix, yielding root-mean-square errors (RMSE) of 0.024%, 0.013%, and 0.007% for S1, S2, and S3, respectively. Through future integration with HgCdTe detectors bonded to the metasurface, the device is expected to achieve on-chip MWIR full-Stokes polarimetry with in-situ readout of polarization-selective photocurrent.