High-Q Photonic Crystal Cavity in a Single-Mode Silicon Ridge Waveguide

We demonstrate experimentally a high-Q one-dimensional photonic crystal cavity in a widely-used 450×220 nm single mode silicon ridge waveguide. Transmission spectrum measurement is performed by using the vertical fiber-grating coupling characterization method. The Q factor up to 2.6×10⁴ is found by fitting the line shape of the transmission spectrum, and the normalized transmission of nearly 20% is achieved. Three-dimensional finite difference time domain calculations show that the modal volume of the fundamental mode is 1.1(λ/n)³. With the standard silicon waveguide width, the demonstrated 1D PhC cavity may be used as a building block for integrated photonic circuits and on-chip sensing applications.