Giving a electrical Input (Voltage input) to a Optical ring resonator


Anybody Can help me with how to provide a voltage input to designed ring resonator using lumerical FDTD.

  1. Can we provide a Voltage input to device in FDTD solutions
  2. Please explain the steps to be followed to provide a electrical(voltage) input.


DC electrode Design for Optical tuning

Dear @durga.prasad0348

Can you please explain what you are trying to simulate and what will be the effect of applied voltage?

You can not apply a voltage to simulations in FDTD. If applied voltage modifies the effective index of the material, you can add the modified material as a new sampled 3D data. For more information please visit the links below:



Hi @bkhanaliloo,
I need to monitor the optical behavior of the ring resonator by applying the voltage. Other than adding a new material can I achieve this using Lumerical Device?..
If possible can you explain how can I do it (like requirements, procedure)

Durga P.


Dear @durga.prasad0348

I am not still quite sure what you are trying to simulate. Can you please explain what would be the effect of applied voltage on material? If, for example, applied voltage modifies the dopant distribution you can use DEVICE to simulate it. Then you can add this material as index perturbed material in FDTD. Please see the link below for more information:

The procedure will be similar to as thermo optic modulators in which you know the temperature at each point of your structure and how material index will be modified by temperature. An step by step explanation on how you can study a heat perturbed material is provided here:



Hi @bkhanaliloo ,
I need measure change in the refractive index when the bias is applied. I created a design for ring resonator in device along with electrodes with following components:

  1. Charge monitor
  2. Charge solver
  3. Electrical contact with voltage 5V
  4. Band structure monitor
  5. Cathode and anode electrodes

I imported the .mat file into np density in lumerical FDTD.

I am not able to see any refractive index change.

Can you help me to solve this.

If any design of ringresonator with charge to index is there please share it with me.



Dear @durga.prasad0348

Thanks for the updates Durgaprasad. Did you introduce an index perturbed material in your material library? Please see the links below:

You can also take a look at PIN Mach-Zehnder KB example, which shows how to use the np grid attribute in MODE, but procedure should be identical to FDTD.

If this did not solve the problem, please update your simulation file for a review.