Circular dichroism is at the core of chiral spectroscopy and polarization light manipulation. However, achieving metal-based devices with high efficiency, compactness, and easy integration in the near-infrared band remains a significant challenge. Traditional metal chiral microstructures, such as broken open rings, helical lines, or waveplates–polarizers I confirm., are limited to circular dichroism values below 50% due to their inherent ohmic losses, severely restricting practical applications. To overcome this bottleneck, this paper proposes a twisted double-layer plasmonic metasurface composed of two anisotropic metal metasurfaces. This design breaks the mirror symmetry of the structure by precisely controlling the in-plane twist angle between the layers, inducing strong coupling and interference effects in the chiral optical response. Simulation results show that this device achieves excellent multi-wavelength circular dichroism control. At a wavelength of 1660 nm, the circular dichroism value reaches 0.48, and it further increases to 0.84 at 2200 nm, significantly surpassing the performance limits of traditional metal structures. This work not only provides a simple and scalable design paradigm for high-performance chiral optical devices but also opens up new avenues for advanced applications such as chiral molecular sensing, polarization coding, and quantum optics in the near-infrared band.

Infrared cameras with narrow-band detection capability are widely used for SF6 gas detection, which is an essential part of power equipment inspection. Narrow-band detection is usually achieved by a combination of quantum well infrared photodetectors (QWIPs) and narrow-band filters. Improving the quantum efficiency of QWIPs and reducing the detection bandwidth are important ways to improve camera performance. In this study, a back-incident-type device of quantum well micropillar array targeting at a 10.5 μm central wavelength is designed and studied by three-dimensional simulation. The operating mechanism of the device was determined by investigating the effect of the device geometry on the quantum efficiency. The enhanced absorption capability of the device mainly comes from the Fabry–Pérot resonance and the antireflection effect. The final device exhibits a remarkable peak quantum efficiency of 83% at 10.5 μm and an ultra-narrow spectral bandwidth of 0.2 μm. These excellent properties are achieved without an antireflective film and narrow-band filter, which can significantly improve the narrow-band capability and integration of the system; the dark current reduces to be 0.2762 times due to the low-duty cycle. These properties indicate that the structure of the quantum well micropillar array is of great significance to the development of QWIPs used in gas detection.

Compared with conventional detectors, a circularly polarized detector operating at 4.26 μm effectively suppresses background noise (e.g., solar scattering and atmospheric interference), enabling high-precision CO₂ monitoring across ecosystems like farmland, forests, and wetlands. This capability allows the precise quantification of carbon sink potential and ecosystem health. Our design employs a mid-wave HgCdTe detector—a well-established platform—combined with a CMOS-compatible Si/SiO₂ metasurface. Geometric displacements were applied to break C₂ symmetry, achieving a chiral design. Through multiparameter optimization, we realized a circularly polarized photodetector (CPPD) with a CPER of 18 dB, expected to demonstrate superior CO₂ monitoring performance. These advances may offer researchers and practitioners a robust tool for both fundamental studies and field deployments.

The on-chip detection of circularly polarized light is pivotal for advancing applications in quantum optics, information processing, and spectroscopic sensing. However, conventional chiral metasurfaces often suffer from complex multilayer fabrication, material incompatibility, or modest performance, hindering their integration with photonic circuits. Here, we introduce a monolithic all-silicon metasurface that overcomes these limitations through a singular structural innovation. By strategically truncating four corners of a conventional Z-shaped meta-atom, we induce a hybridization of optical modes that profoundly enhances chiral light–matter interaction. This deliberately engineered perturbation yields a colossal circular dichroism with an extinction ratio exceeding 66 dB, a performance that surpasses existing state-of-the-art designs by approximately three orders of magnitude. Furthermore, the proposed metasurface exhibits remarkable fabrication robustness, owing to its single-layer architecture and CMOS-compatible material. We demonstrate that this exceptional metasurface can be directly integrated with a Mercury Cadmium Telluride (MCT) photodetector to form a highly efficient, compact circular polarization detector. Our work provides a simple yet powerful paradigm for creating high-performance chiral photonic devices, paving the way for their widespread adoption in integrated optoelectronics.

Conventional chiral metasurfaces are typically restricted to a single resonant wavelength, which limits their ability to satisfy the requirements of broadband detection and multi-channel polarization manipulation. To overcome this limitation, this study numerically proposes a chiral metasurface based on an oracle-bone-inspired geometry. By combining dislocation with rotational symmetry breaking, the proposed structure enables pronounced circular dichroism responses at three wavelengths in the long-wave infrared region, reaching 0.68@λ₁ = 10.43 μm, 0.79@λ₂ = 10.8 μm, and 0.6@λ₃ = 10.9 μm. This design overcomes the single-wavelength limitation of conventional chiral metasurfaces and establishes a new paradigm for multi-wavelength chiral light-field manipulation. This research not only broadens the design scope of chiral photonics, but also provides a promising technical path for the development of highly integrated infrared polarization devices and multi-wavelength chiral sensing systems.

Mercury Cadmium Telluride (MCT) photodetectors operating in the long-wave infrared (LWIR) band play an indispensable role in infrared sensing and imaging. However, conventional MCT detectors respond only to the intensity of incident light and lack the ability to resolve polarization information—polarization being a critical dimension of the electromagnetic field essential for target recognition and scene understanding in complex environments. We overcome this fundamental limitation by monolithically integrating a compact module composed of six individual bilayer metallic metasurfaces onto a planar junction MCT detector, enabling full-state detection of the polarization state of incident light. The metasurface module includes four linear polarization filters with a peak transmission efficiency of 83% and extinction ratios up to 74 dB, as well as two circular polarization filters achieving a transmission efficiency of 94% and an extinction ratio of 36 dB. The circular polarization functionality is realized by tuning the twist angle between the upper cross-shaped metal nanoparticles and the lower trapezoidal structures, thereby breaking spatial symmetry and inducing strong chiral optical responses. The observed ultra-high efficiency arises from the hybridized coupling between localized surface plasmon resonances (LSPRs) supported by the two metal layers. This fully polarimetric MCT photodetector offers both high efficiency and a compact architecture, demonstrating considerable potential for polarimetric infrared imaging, target detection, and quantum information processing.