Learning Forum

[bailin.zhang]

Hello,

How to write the merit figure function to optimize a grating to obtain a specific diffraction efficiency for example 10% for the first order?  Thank you.

[Kyle]

Hello,

To optimize for a specific value you can minimize the difference between the result and the target value. For example:

FOM = abs(diffraction_efficiency - 0.1)

[bailin.zhang]

Thank you for the answer, Kyle

by the way another question about the optimiztion: For the RCWA link between and zemax opticstudio. Due to there are optimization for both of them. The practical optimization merit function is decided by the one in zemax opticstudio ?  and the parameters are limited by Lumerical FDTD? 

[Kyle]

You're welcome. Yes, I think your understanding is correct. If you are using the Zemax-Lumerical RCWA dynamic link to do the optimization, then you are only using the Zemax optimization features, the Lumerical optimization tools are not involved at all.

The parameters of the grating on the Zemax side are treated like normal Zemax parameters for the optimization. These parameters changed by Zemax's optimization features, and are passed to Lumerical to modify the grating geometry according to the parameters.

The results of the diffraction efficiency simulations with those parameters are then calculated by Lumerical RCWA and passed back to Zemax.