Continuously tunable heterostructure air-slot nanocavities in two-dimensional photonic crystals

We present tunable double and multistep heterostructure air-slot nanocavities in two-dimensional silicon photonic crystals by introducing structural changes. Through changing the air-slot width, air hole radius and air hole position in the cavity region, the continuous tunability in resonant frequency and Q value can be realized synchronously in a wide frequency bandwidth. Finite-difference time-domain methods are used to study the optical properties of the nanocavities and the attainable Q exceeds 106 in a wide frequency range of 0.0152 a/λ. The results show that our designs may be promising for constructing flexible photonic devices with broadband and controllable frequency tuning.