Tuning of High-Q Photonic Crystal Microcavities by a Subwavelength Near-field Probe

(Dated: Prepared for Phys. Rev. December 15, 2004)We demonstrate that the resonance frequencies of high-Q microcavities in two-dimensional pho-tonic crystal membranes can be tuned over a wide range by introducing a subwavelength dielectrictip into the cavity mode. Three-dimensional finite-difference time-domain (FDTD) simulationsshow that by varying the lateral and vertical positions of the tip, it is possible to tune the resonatorfrequency without lowering the quality factor. Excellent agreement with a perturbative theory isobtained, showing that the tuning range is limited by the ratio of the cavity mode volume to theeffective polarizability of the nano-perturber.