A mid-infrared high-performance spectropolarimetry filter based on dual-mode independent modulation

Spectropolarimetry detection provides multi-dimensional accurate information with broad applications from biomedicine to remote sensing. Existing methods for simultaneously obtaining spectra and polarizations are either large and complex systems or miniaturized devices with too low spectral resolution or poor polarization selectivity, which inherently generate cross-talk of substantial information. Here, we propose a compact and single-chip integrated high-performance mid-infrared spectropolarimetry filter (SPF), whose narrowband spectral and polarization characteristics can be independently modulated by different polarization modes. A SPF is designed with a polarization extinction ratio (ER) over 10⁶, spectral resolution (SR, λ/Δλ) up to 822 and a transmission efficiency of 90% in the mid-infrared band. The experimental ER and SR are over 3 × 10⁴ and up to 387 respectively with a transmission efficiency of 60%. These results agree well with the theoretical results and can accurately obtain spectral and polarization information simultaneously. This device has been used in tumor diagnostics to well distinguish striated muscle and rhabdomyosarcoma tissue for demonstration. It can be easily extended to different wavelength ranges and provides a new and powerful approach for multi-dimensional optical information acquisition, target detection and accurate identification.