All-optical control of a single resonance in a graphene-on-silicon nanobeam cavity using thermo-optic effect

We propose and demonstrate on-chip all-optical control of a single resonance in a graphene-on-silicon nanobeam cavity using thermo-optic (TO) effect. In the design, the graphene sheet covered on the nanobeam cavity is patterned in a U shape, which enables the device to maintain a constant quality factor and a high extinction ratio (ER) after graphene transfer. Benefiting from the ultra-small optical mode volume of the nanobeam cavity and the high thermal conductivity of graphene, efficient all-optical control of a single resonance is implemented with a tuning efficiency of 0.0346 nm/mW. All-optical switching is also demonstrated with a switching power of 47 mW at a high ER of ~16 dB. Moreover, the 10%90% switching times are 3.24 s and 5.52 s for the rising edge and the falling edge, respectively. Such graphene-assisted device potentially could be a good candidate to realize efficient on-chip all-optical control of an individual resonance with a high ER.