I am running an optimization similar to what I have described in a previous post with the same Lumerical version:
I am running into an issue where the optimization works quite nicely (and I am able to achieve quite low loss structures), but occasionally lumopt freezes at what I assume is the gradient calculation. Usually it takes a minute or two to calculate the gradients, but when it freezes, I can wait for several hours, and nothing happens. See figure below for where it exactly freezes:
If I run the same optimization again, it freezes at exactly the same spot. I have been able to circumvent this problem by changing the input parameters slightly, which also changes the gradients, but this is not a solution to the problem.
I was wondering what could be causing this.