Resonance search

What it finds

For 1D grating a search of incident plane wave resonance with a waveguide mode supported by the multilayer grating structure is available. This function includes search of double resonances in two different diffraction orders. The search results are effective refractive indexes of structure modes, resonance positions, resonance width and associated with the resonance poles parameters [13] in a complex plane with the wave vector projection on a grating and radiation coefficient as a coordinates.

In the documentation's words, the search is aimed at anomalies of the reflected and transmitted waves when the incidence angle is changed in a fixed incidence plane, caused for example by excitation of the waveguide modes of the dielectric structure. When the Resonance page opens, the software first estimates the waveguide parameters by computing the mode effective indices of the multilayer with the grating regions averaged into uniform layers, and the exact search then starts from those estimates for the selected polarization.

What it feeds

The pole parameters are what the Analysis dialog uses in its pole approach to the reflection and transmission of a finite Gaussian beam — the alternative to its FFT approach — so a resonance search followed by an analysis gives the beam response of a resonant mirror or filter without scanning it. Resonance positions can also be the targets of the optimizer's criterion function in the collinear codes.

Where

Available in the four one-dimensional codes; added to the conical and the 2D versions in the 2016-11-02 release. The modes-interference study follows these resonances into high-contrast gratings.

Resonance search is a Full-edition feature; the Light edition computes diffraction efficiencies only.