Extended Data Fig. 2: Simulated mode profiles and mode volumes for the unit cell and the photonic crystal defect modes build on this cell.
From: High-Q slow light and its localization in a photonic crystal microring
a,b, Top view and cross-section view of s0 FEM-simulated mode profiles in a unit cell with m = 162 and A = 1150 nm. The calculated resonance frequency is 191.0 THz, within 1 THz of the experimental data (Fig. 2e). The mode volume for a unit cell is 0.20 μm3, that is, 0.40(λ/n)3, with η = 86 % confinement factor in Si3N4. The mode volume of s0 over the whole ring is 64(λ/n)3. c, Photonic crystal (PhC) defects can be built based on (a). Such dPhC cavity modes are created by a reduction in A (Δ) by 10 % (magenta) to 30 % (black) at the defect center, and a quadratic grading in A over N cells is shown. The mode volumes can be further optimized by using a larger Δ and an optimized N, or using material stacks with larger refractive index contrasts, for example, silicon on insulator (SOI). d,e, Two examples of the dPhC mode (g) with {N, Δ} = {16, 30 %} and {48, 10 %}, with mode volumes of 3.3(λ/n)3 and 5.5(λ/n)3, respectively.
