Slow light in dual-periodic photonic crystals based slotted-waveguide coupled cavity

Abstract

Considering the capacity of the nanoscale width area with the low-refractive index can confine light waves, the dual-periodic slotted photonic crystals, which is constructed by coupling low-refractive index's slotted-waveguide with high-refractive index's cavity is proposed in this paper. The best slow light properties and the optimal slotted-waveguide coupled cavity are achieved by adjusting the slotted-width and the period of cavity respectively. In this structure, the slow-light properties are simulated by Plane Wave Expansion (PWE), the result reveals that the group velocities are all three orders of magnitude smaller than the speed of light in vacuum, the slowest value is 7.96×10−4c when the slotted-width is 0.54a and the period of cavity is 0.95a. Moreover, the corresponding Normalized Delay-Bandwidth Product (NDBP) values are larger than 0.24. Besides, the slotted-waveguide coupled cavity can be reconfigured, which accordingly changes the corresponding slow-light property. At last, the numerical results provide a new thought and method for decreasing group velocity and potential application for optical buffer in photonic crystals field.