Polarization-Resolved Chlorophyll Imaging for Non-Invasive Plant Tissue Assessment Using a Silicon-Rich Nitride Metalens Array

Abstract

Polarization-sensitive imaging enhances contrast and reveals structural features in biological tissues that are often missed by intensity-based methods, but its adoption is limited by bulky optics. We present a compact silicon-rich nitride (SRN) metalens array for high-resolution, polarization-resolved imaging of plant tissue at the chlorophyll absorption peak (660\,nm). The array integrates orthogonally sensitive metalenses to simultaneously capture X- and Y-linearly polarized transmission images, enabling real-time, label-free assessment of plant microstructure and stress responses. Polarization fusion and difference mapping reveal structural anisotropy and pigment variation in both healthy and stressed leaves. The SRN metalens, designed via an inverse approach using birefringent meta-atoms and fabricated through CMOS-compatible processes, achieves a large numerical aperture, high transmission, and spectral alignment with biological absorbers. This work demonstrates the feasibility of compact, integrated polarization-resolved imaging, offering a scalable alternative to conventional systems. The approach holds potential for biomedical and agricultural applications, where detecting subtle polarization-dependent changes could enable early diagnosis and tissue characterization