High-Q cavity based on gradated one-dimensional photonic crystal

A high quality-factor (Q) cavity based on a one-dimensional (1D) photonic crystal with gradated elliptical holes was designed using FDTD simulation. Different gradient profiles of the mirror holes were found to correspond to different Q-values of the cavities. A simple strategy is proposed to construct high-Q cavities by using an S-shaped gradient profile for the elliptical holes' minor axes, such as a cosine function or Gaussian function. Using such a strategy, a Q value exceeding two million is obtained with only ten mirror holes in a cavity.