Band-Gap Analysis of a Photonic Crystal
Application ID: 798
This model investigates the wave propagation in a photonic crystal that consists of GaAs pillars placed equidistant from each other. The distance between the pillars determines a relationship between the wave number and the frequency of the light, which prevents light of certain wavelengths from propagating inside the crystal structure. This frequency range is called the photonic bandgap. There are several bandgaps for a certain structure, and this model extracts the bandgaps for the lowest bands of the crystal.
There are two main complications with a bandgap analysis. Firstly, the wave vector must be ramped to produce the band diagram, which is addressed with a parametric sweep. Secondly, the refractive index of GaAs is frequency dependent, creating a nonlinear problem. This is handled with the use of a nonlinear eigenfrequency solver. The nonlinear solver finds the correct eigenfrequencies, then, with the use of mode following, sorts these into the applicable bands.
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