High-Q Fano resonance based on degenerate modes in a single dielectric point-defect photonic crystal cavity with x-y asymmetry

We designed multiple degenerate modes in a single-point-defect photonic crystal cavity with x-y-asymmetry to act as bright and dark modes to produce Fano resonances. Under suitable operating parameters, the power-flows in incident-direction for two degenerated modes cancel each other, resulting high Q-factors for Fano modes. Extremely-high Q-factor of Fano resonances exceeding 10(8) with transmittance larger than 0.867 is obtained based on modes with Q-factors less than 10(4), and in further exploration, the Q-factor can reach 3 x 10(10). This method provides a basis to design compact, high-Q Fano devices for extremely high-sensitivity biosensing, switching and lasing. (C) 2020 The Japan Society of Applied Physics.