Enhancing light absorption in two-dimensional (2D) materials, particularly few-layer structures, is critical for advancing optoelectronic devices such as light sources, photodetectors, and sensors. However, conventional absorption enhancement strategies often suffer from unstable resonant wavelengths and low-quality factors (Q-factors) due to the inherent weak light–matter interactions in 2D materials. To address these limitations, we propose an all-dielectric metasurface graphene-perfect absorber based on toroidal dipole bound state in the continuum (TD-BIC) with an ultra-narrow bandwidth and stable resonant wavelength. The proposed structure achieves tunable absorption linewidths spanning three orders of magnitude (6 nm to 0.0076 nm) through critical coupling modulation. Furthermore, the operational wavelength can be flexibly extended to any near-infrared region by adjusting the grating width. This work establishes a novel paradigm for enhancing the absorption of 2D materials in photonic device applications.

The absence of natural sources of circularly polarized light has created a critical demand for high-performance polarization converters in emerging technologies such as quantum information processing, biomedical diagnostics, and advanced magneto-optical recording systems. Despite significant efforts, linear-to-circular polarization converters that combine high efficiency with tunability remain scarce. In this paper, we present a multifunctional and tunable device with 99.9% efficiency for converting linear to circular polarization in the telecom wavelength range. It can also function as a phase-only compensator with a controllable phase range of 1.93$\pi$ while maintaining a reflectance above 99%. The angular sensitivity analysis indicates that the device can tolerate incidence angles ranging from 8 to 10.4 degrees. This high-efficiency polarization conversion device offers significant advantages in integrated optics due to its multifunctionality and tunability and has promising applications in optical phased-array radars and quantum communication.