Spectral tuning of multimode three-dimensional photonic crystal cavities for enhanced anti-Stokes Raman scattering

Multimode hollow microcavities in three-dimensional (3D) photonic crystals (PhCs) are designed for achieving enhanced coherent anti-Stokes Raman scattering, which requires a cavity to have three high quality-factor (Q) modes with equally spaced resonant frequencies. Cavities in 3D PhCs allows more flexibility in design and tuning than their 2D slab counterparts, since radiation loss that degrades Q can be suppressed by the 3D photonic band gap. We first tune all the mode frequencies simultaneously by changing the material and geometry of the cavity based on perturbation theory. Spectral spacings between the multiple modes are adjusted according to the symmetry, volume and field distribution of their mode profiles. The frequency and field distribution of the resonant modes are computed by solving Maxwell's equations in the frequency domain.