As a critical technology for high spatial resolution and accurate polarization detection, the division of focal plane (DoFP) polarization detectors is achieved via the integration of micro-polarizer arrays (MPAs) with image sensors. These detectors are pivotal in numerous applications, ranging from remote sensing and biomedical imaging to military surveillance and industrial process monitoring. However, their potential is restricted by performance problems caused by crosstalk, which degrades the extinction ratio (ER) and reduces detection accuracy. Arising from both optical and electrical interactions, crosstalk negatively influences polarization measurement precision, thereby limiting the broader adoption of DoFP polarization detectors in high-performance systems. Despite their increasing importance, comprehensive analyses of crosstalk mechanisms and effective mitigation strategies remain insufficient. We aim to systematically investigate the origins and effects of crosstalk, analyze its influence on ER, and introduce an innovative solution to suppressing crosstalk by a novel optoelectronic isolation design. This approach addresses both optical and electrical crosstalks for enhancing the functionality and reliability of DoFP polarization detectors.

Key findings of our study include the following aspects. 1) Theoretical analysis. Our study starts with a systematic analysis of crosstalk mechanisms to identify contributing factors. Optical crosstalk is primarily caused by diffraction and reflection processes within the detector’s structural layers, and electrical crosstalk arising from charge diffusion across adjacent pixels is quantified and evaluated. Meanwhile, their collective effects on ER are modeled to highlight critical performance bottlenecks. 2) Numerical simulation. Simulations play a central role in validating the theoretical findings and exploring mitigation strategies. A front-side illuminated (FSI) dual-pixel DoFP detector model is developed and simulated by adopting the FDTD and CHARGE modules in Ansys Optics Launcher 2024 R1. The simulations focus on electromagnetic field distributions and charge transport phenomena, enabling accurate predictions of pixel-level crosstalk. By employing these tools, the ER is evaluated based on simulation-derived electrical parameters, which provides quantitative insights into the degradation mechanisms and tests of the proposed design concepts for mitigating crosstalk. 3) Experimental verification. MPA is directly fabricated on the photosensitive surface of a commercial CMOS image sensor (CMV4000) based on focused ion beam (FIB) technology. The detector contains 0°, 60°, and 120° polarization strips, which are composed of sub-wavelength Al gratings. Additionally, a line shape light source polarization testing system based on a cylindrical mirror is built to measure the polarization transmittance and quantify the crosstalk between pixels [Figs. 7(b) and 9].

Crosstalk mechanisms. Analysis reveals that optical crosstalk primarily originates from diffraction phenomena in the thick passivation layers and scattering by internal metallic structures, particularly the electrodes. In contrast, electrical crosstalk arises from carrier migration across pixel boundaries, significantly impairing ER. Finally, the undesired interference degrades ER. Fabrication and testing. The fabricated DoFP polarization detector demonstrates polarization transmittance curves with distinct sinusoidal characteristics. The measured crosstalk percentages for adjacent pixels reach as high as 19.26% (Table 2). Optoelectronic isolation design. To mitigate crosstalk, we propose a novel optoelectronic isolation strategy, which leverages Al conductors embedded within silicon dioxide insulators to block both photon migration and electron migration (Fig. 11). Simulations of this design demonstrate a substantial reduction in crosstalk, leading to significant ER improvements. Notably, the electrical ER reaches values that approach the intrinsic limits set by the MPA design itself (Fig. 12), thereby emphasizing the effectiveness of the proposed solution.

We systematically half-quantify the influence of crosstalk on the performance of DoFP polarization detectors and introduce a novel optoelectronic isolation strategy as an effective countermeasure. By combining theoretical modeling, numerical simulations, and experimental validation, we provide a comprehensive understanding of the mechanisms underlying optical and electrical crosstalks. The proposed design successfully suppresses both forms of interference, leading to significant enhancements in ER and overall detector performance. These findings provide both a valuable foundation for the design and development of high-performance DoFP polarization detectors and a reference for the integration of other array metasurfaces and planar array detectors. In the future, more complex detector models, real structures, and doping parameters will be adopted to quantitatively study the influence of photoelectric isolation.