Optical absorption enhancement of bilayer graphene-based integrated microcavity

Bernal stacking bilayer graphene is a promising candidate with controllable energy gap for large scale optical devices. However, the initial weak light absorption of bilayer graphene precludes many optoelectronic applications. Here, we theoretically propose a bilayer graphene-based integrated microcavity structure consisting of two distributed Bragg mirrors to enhance the absorptance. Our results demonstrate that the absolute light absorptance of proposed microcavity can be improved for more than 41 times compared with free standing monolayer graphene. A strong dependence of enhancement on the top mirror’s pairs and the cavity length is found, which alerts a more strict accuracy demand on their thickness controls. The pairs of bottom mirror need to be considered evenly between high reflectance and processing. Besides, the range of bilayer graphene’s spatial position for attenuation less than 0.1 dB from peak absorptance occupies one-fifth of the cavity length. This favorable enhancement of bilayer graphene’s absorption could provide a thrilling path toward high-responsivity, ultrafast response and wavelength-selectivity optoelectronic devices.