Frequency tuned air-slot mode-gap cavities in two dimensional photonic crystals

•Frequency tuned air-slot mode-gap nanocavities are obtained.•Frequency can be continuously tuned almost covering the entire mode gap region.•The cavity’s resonant frequency is very sensitive to the shape alteration.

We present frequency tuned air-slot mode-gap nanocavities in two dimensional photonic crystals by introducing elliptical air holes in the cavity region. Shape alteration from the regular circle to ellipse offers a great structural freedom to tune the optical properties of the nanocavities. By changing the ellipticity and orientation angle of the ellipse, the resonant frequency of nanocavities can be continuously tuned almost covering the entire mode gap region. It is also found that the resonant frequency is very sensitive to the shape alteration and the fine tuning of the cavity resonant frequencies can be performed. The results show that our designs can be used to construct flexible PC devices with broadband and controllable frequency tuning.