Mid-infrared semimetal polarization detectors with configurable polarity transition

On-chip polarization-sensitive photodetectors offer unique opportunities for next-generation ultra-compact polarimeters. So far, mainstream approaches have relied on the anisotropic absorption of natural materials or artificial structures. However, such a model is inherently restricted by correlation between the polarization ratio (PR) and diattenuation, leading to small PR values (1 < PR < 10). Here, we report nanoantenna-mediated semimetal photodetectors, which enable configurable polarity transition by exploiting the vectorial and non-local photoresponse in semimetals. By tuning the orientation of nanoantennas, PR values vary from positive (unipolar regime) to negative (bipolar regime), covering all possible numbers (1 -> infinity/-infinity -> -1). In particular, the PR values at the polarity-transition point could approach infinity. Such a polarity transition hereby transcends the conventional PR-diattenuation relationship. Furthermore, our device allows the subtle measurement of polarization-angle perturbation down to 0.02 degrees Hz(-1/2) in the mid-infrared range. Our findings highlight the potential of semimetals as a promising material platform for miniaturized polarimetry. Mid-infrared polarization detectors based on nanoantenna-mediated few-layer graphene are demonstrated. By tuning the orientation of nanoantennas, the polarization ratios vary from positive to negative, and cover values from 1 to infinity/-infinity then to -1.

Automated summary

A nanoantenna-mediated semimetal photodetector, capable of configurable polarity transition and covering a wide range of polarization ratios from positive to negative values, has been reported. This device breaks the conventional relationship between polarization ratio (PR) and diattenuation, allowing for PR values to approach infinity at the polarity-transition point.