Two-dimensional layered material/semiconductor heterostructures have emerged as a category of fascinating architectures for developing highly efficient and low-cost photodetection devices. Herein, we present the construction of a highly efficient flexible light detector operating in the visible-near infrared wavelength regime by integrating a PdTe₂ multilayer on a thin Si film. A representative device achieves a good photoresponse performance at zero bias including a sizeable current on/off ratio exceeding 10⁵, a decent responsivity of ~343 mA/W, a respectable specific detectivity of ~2.56 × 10¹² Jones, and a rapid response time of 4.5/379 μs, under 730 nm light irradiation. The detector also displays an outstanding long-term air stability and operational durability. In addition, thanks to the excellent flexibility, the device can retain its prominent photodetection performance at various bending radii of curvature and upon hundreds of bending tests. Furthermore, the large responsivity and rapid response speed endow the photodetector with the ability to accurately probe heart rate, suggesting a possible application in the area of flexible and wearable health monitoring.

We systematically investigated the tunable dynamic characteristics of a broadband surface plasmon polariton (SPP) wave on a silicon-graded grating structure in the range of 10–40 THz with the aid of single-layer graphene. The theoretical and numerical simulated results demonstrate that the SPPs at different frequencies within a broadband range can be trapped at different positions on the graphene surface, which can be used as a broadband spectrometer and optical switch. Meanwhile, the group velocity of the SPPs can be modulated to be several hundred times smaller than light velocity in vacuum. Based on the theoretical analyses, we have predicted the trapping positions and corresponding group velocities of the SPP waves with different frequencies. By appropriately tuning the gate voltages, the trapped SPP waves can be released to propagate along the surface of graphene or out of the graded grating zone. Thus, we have also investigated the switching characteristics of the slow light system, where the optical switching can be controlled as an “off” or “on” mode by actively adjusting the gate voltage. The slow light system offers advantages, including broadband operation, ultracompact footprint, and tunable ability simultaneously, which holds great promise for applications in optical switches.