Fig. 4: Fast simulations with coupled mode theories (CMTs).
a Far-field intensity simulation of a metasurface using temporal coupled mode theory (TCMT)32. a.i Schematic of a large-area metasurface comprising M interconnected resonators. a.ii Comparison of normalized intensity profiles derived from the CMT and finite element method (FEM). a.iii Comparison of the computation times of CMT (black squares) and FEM simulations (red circles), achieving faster results by several orders of magnitude. a.iv Total field intensity from a metalens with a size of 10,000λo. b Multi-resonance characteristic simulations using multi-resonance TCMT87. b.i Emission spectrum of an infinite array of coupled hBN ribbons. b.ii Comparison of the computation times of the CMT (blue) and rigorous coupled-wave analysis (RCWA; red). b.iii Structure and absorbance result of the neural network–combined CMT model. c Far-field intensity simulation of a metasurface using the spatial coupled mode theory (SCMT)90. c.i Schematic of a large-area metasurface comprising interconnected waveguides. c.ii Point spread functions of the SCMT (red) and finite difference time domain (FDTD; black). c.iii Focal efficiency comparison designed by local periodic approximation and SCMT. c.iv Comparison of the computation times of the SCMT (red) and FDTD (black). d Nonlocal metasurfaces with spatially invariant meta-atoms using TCMT and those with spatially variant meta-atoms using spatiotemporal coupled mode theory78. e Schematic of the quasi-normal coupled mode theory system82.
