(a) The schematic of the resonant cavity enhanced graphene photodetector and the corresponding electric field distribution. Red arrow: the position of graphene. (b) The dashed lines indicates the calculation result: reflection R (red), transmission T (green), and absorption A (blue), while the solid lines indicate the measurement result: reflection (red) and photocurrent (blue). A 26-fold absorption enhancement at the cavity resonance wavelength (855 nm). Inset: calculated theoretical results. (c) Schematic diagram of the resonant cavity enhanced graphene/Si Schottky photodetector. (d) The response spectrum of the device with and without Au mirror. A 3-fold absorption enhancement can be observed in the presence of Au mirror. The blue shift of the resonance peak is caused by the difference between different devices. Panels (a)–(b) are reproduced from Ref. [123] with permission from the American Chemical Society. Panels (c)–(d) are reproduced from Ref. [124] with permission from the American Chemical Society.