  Thermally-tuning silicon micro-cavities are versatile and beneficial elements
in low-cost large-scale photonic integrated circuits (PICs). Traditional metal
heaters used for thermal tuning in silicon micro-cavities usually need a thick
SiO2 upper-cladding layer, which will introduce some disadvantages including
low response speed, low heating efficiency, low achievable temperature and
complicated fabrication processes. In this paper, we propose and experimentally
demonstrate thermally-tuning silicon micro-disk resonators by introducing
graphene transparent nano-heaters, which contacts the silicon core directly
without any isolator layer. This makes the graphene transparent nano-heater
potentially to have excellent performances in terms of the heating efficiency,
the temporal response and the achievable temperature. It is also shown that the
graphene nano-heater is convenient to be used in ultrasmall photonic integrated
devices due to the single-atom thickness and excellent flexibility of graphene.
Both experiments and simulations imply that the present graphene transparent
nano-heater is promising for thermally-tuning nanophotonic integrated devices
for e.g. optical modulating, optical filtering/switching, etc.
