Sweep over TWLM length


I am working on a DFB laser design, and currently I am interested in how different model parameters affect the modulation bandwidth. I use a circuit from this example and function from this example to get the bandwidth.

The problem appears when I want to see how laser length affects the bandwidth, because when I sweep over length value, TWLM divides different lengths into different number of sections, therefore output matrices are of different size, and Lumerical does not save the sweep results.

So the question is, is it possible to make a sweep over length of TWLM element in INTERCONNECT? I have a hunch that maybe I need to change sample rate value simultaneously with length, in this case the number of sections after division stays the same, but then time domain fracturing is affected, so again I get matrices of different dimensions at the output and cannot analyze the result meaningfully.

Hi @a.zozulia,

To follow up on Kyle’s point, the number of sections is resolved by the solver automatically so you are right that increasing the sample rate may affect it’s value. And if you know the max number of sections used in the sweep, you may change the minimum number to be it. Other than this, you can add sample rate dependency on the laser length, but rather than directly collect the results from the analyzers (as mentioned with different number of samples, the total length of the data varies), you can add some script into the Root Element analysis script tab to format the result first, then use those results as the sweep result. Let me know if this sounds reasonable and I can help to write up an sample example for this.

Note that you can also change the sample rate, but keep the same number of samples in the simulation if this is reasonable to your design.

Hope this can help.