Electro-absorptive modulator


Dear Sir,
I am new to lumerical. does lumerical support “franz keldysh effect”? Can u provide me any example related to electro-absorptive modulator?


Hi @sourabh.jain, Yes Lumerical solvers can help you model Franz-Keldysh effect in an electro-optic modulator. You will have to first perform an electrical simulation of your modulator using the CHARGE solver in DEVICE. The electrical simulation will give you the electric field in the modulator. Next you can transfer this electric field data into Lumerical’s optical solver (either MODE or FDTD depending on your specific design) and calculate the variation in the optical index of the electro-optic material. Finally you can run an optical simulation in the optical solver to calculate the optical performance of the modulator.

A relevant example for you would be this photonic crystal modulator example in KB: Nanobeam PC Modulator. Note that the example uses a “structure group” in FDTD to create a new material whose index is calculated using the electric filed data saved by the CHARGE solver. You can use the same structure group in MODE as well (if that is the more suitable solver for your device). The only thing to remember is that you will have to use your own equation for the index perturbation (suitable for the electro-optic material used in your device).


Thankyou for replying sir. I have one more question,
can i do same thing using charge monitor? and what is basic difference change and electric field monitor?


Hi @sourabh.jain, As the names suggest the charge monitor allows you to record the charge density over a certain volume/area while the electric field monitor allows you to record the electric field over the same. Since the Franz-Keldysh effect perturbs the index due to electric field in the material you will need an electric field monitor. If you are also interested in modeling the plasma dispersion effect which perturbs the optical index as a function of variation in charge density then you will need to use a charge monitor.


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