Synergistic-potential engineering enables high-efficiency graphene photodetectors for near- to mid-infrared light

This indicates that both the slit structure and back-gate voltage can improve the device responsivity by enhancing the interface electric field. This observation also helps clarify whether the interface electric field can effectively affect the photogating mechanism for such structures (More details can be seen in Supplementary Figs. 9 and 10 of Supplementary Note 2). Polarization sensitive detection The configurable dielectric structure provides us with a platform that can be flexibly designed according to our requirements to achieve functional detection with high responsivities, such as polarization sen- sitive detection. Currently, on-chip integrated polarization-sensitive detectors mainly rely on anisotropic two-dimensional materials or metasurface structures7,24,46–49. Anisotropic metal metasurface struc- tures can compensate for the low polarization ratio of anisotropic materials. However, most face the problem of low responsivity. Here, the gain induced by electrical field engineering can synergistically interact with the anisotropic distribution of light field. By designing the dielectric material that can serve as photogating trap material into an anisotropic structure, we can effectively achieve polarization sensitive detection with high responsivity. With the design parameters set to DC = 0.3, H = 160 nm, and L = 1 µm, the structure exhibits a high reflec- tion polarization ratio for light of 1.55 µm in the X (perpendicular to the grating) and Y (parallel to the grating) polarization directions, as shown in Fig. 4a. The simulation (dots) and experimental measurements (lines) of far-field characteristics are highly consistent (See Supplementary Fig. 11 for different DCs). We can refer to the points with the strongest and weakest reflections as R point and A point. The electric field dis- tribution caused by the incidence of polarized light inside the grating exhibits significant differences. From the near-field characteristics of the light field intensity distribution corresponding to the incident light at 1.55 µm (Fig. 4b), it can be seen that Y-polarized light is largely reflected (R point). In contrast, X-polarized light is localized around the silicon strip (A point), leading a difference in absorption of graphene, as shown in Supplementary Fig. 12. Supplementary Fig. 13 in Supplementary Note 3 shows the near-field distribution under different polarization angles of light. Hence it will have an impact on the number of photo- generated carriers participating in the photogating process, further leading to varying degrees of gain. The measured chopping signals with different polarization angles are shown in Fig. 4c. The linear polarization state of the incident light at 1.55 µm is controlled via rotation of the half- wave plate (HWP). It can be observed that as the polarization angle of the incident light changes, the near-field enhancement of the structure and the measured photocurrent show a high degree of correlation, including the corresponding “R” and “A” points, as shown in Fig. 4d. Through multiple measurements, a sinusoidal function relationship between the photocurrent and the polarization angle can be obtained, as shown in Fig. 4e. The maximum polarization ratio is 10, and the responsivity is about 1.43 A/W. In addition, by adjusting the structural DC to 0.8, polarization sensitive detection can be achieved at wave- length of 4 µm, as shown in Fig. 4f (See Supplementary Fig. 14). Never- theless, in the case of the 2D slitstructure, no particular resonance mode exists for the test wavelength range, making it suitable for emphasizing its remarkably high responsivity characteristics. Based on these struc- ture, more flexible designs can be achieved, for example, by modulating the conductivity of graphene through gate voltage, one can tailor polarization ratio and wavelength, as shown in Supplementary Fig. 15 of Supplementary Note 3. Blackbody characterization of device Blackbody detection, as a detection standard for practical applica- tions, is used to demonstrate the infrared detection performance of photodetectors. Further, we investigated the devices for blackbody detection at room temperature. Figure 5a presents the schematic diagram of the blackbody detection system. The blackbody source is Cisystems SR200N with an adjustable temperature from 500 K to 1200 K. The device was placed in front of the aperture