change in phase in a optical modulator using dc voltage should be first simulated in CHARGE, and then import the carrier density as np density attribute. Please refer to this example: https://optics.ansys.com/hc/en-us/articles/360042456054-Electro-absorption-modulator
or
https://optics.ansys.com/hc/en-us/articles/360042328774-Traveling-Wave-Mach-Zehnder-Modulator
https://optics.ansys.com/hc/en-us/articles/360034901753-np-Density-and-Temperature-Index-Perturbation-Simulation-objectÂ
The data should be effective index vs voltage for INTERCONNECT use.
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