Fig. 2
From: Ultrafast perturbation maps as a quantitative tool for testing of multi-port photonic devices
Validity of the reciprocity-based model for sub-wavelength perturbations. The photonic structure is a 1 × 2 MMI device of length L = 33.2 μm and width W = 6.0 μm operating at 1.55 μm (see Methods for more details). a Norms of the background electric field generated by ingoing excitations from the fundamental modes of the input and upper output waveguides, \(\left| {{\bf{E}}_{{\mathrm{b}},m}^ + } \right|\) and \(\left| {{\bf{E}}_{{\mathrm{b}},n}^ + } \right|\), respectively. b Resulting perturbation map as predicted using Eq. (8) for a cylindrical perturbation of diameter 2R = 10 nm and refractive index variation Δn = −0.25. c Comparison between the perturbation curves for the same system along a cut (black dotted line in b) obtained from a-FMM performed for each perturbation position (fully-numerical, blue solid line), and predicted from the reciprocity-based model (yellow dotted line)
