▎ 摘　　要

We demonstrated a polarization-sensitive photodetector based on periodically crossed graphene ribbons theoretically. Localized surface plasmon is generated by patterned graphene structure with significantly enhanced incident light absorption. Broadband detection is observed from 10.5 to 16.5 mu m. Moreover, the photoresponsivity reaches up to 1.717 A W-1 at the wavelength of 12.58 mu m under 0 degrees polarization, and the photoresponsivity is 0.212 A W-1 under 90 degrees polarization. The tunability of photodetectors is achieved by changing the gate voltage to modulate the chemical potential of graphene. The finite difference time domain solutions are used to predict the performance of the photodetector with different polarization angles for longwave infrared (LWIR) light. The polarization-sensitive, tunable and broadband graphene photodetector provides a promising direction for high performance LWIR detection at room temperature.