Transient response of DFB TWLM element

Dear community,

I have a problem with the transient response of a DFB laser using the TWLM element. I try to reproduice the response of a DFB laser with parameters took from the reference [1] (as you can see down below), that’s look like the right figure:

,Transiant resp

So here is my current circuit with a OOSC_1 to visualize its transient response.


But, as you can see on the right, I get a very noisy response that I still can’t understand. However, the model should technically give the same output as the paper one since it’s also simulate a TD-TWM.

my concern is to know if there is an error in the definition of my parameters in the TWLM element.

Thank in advance for your help.


M. M. Bouchene and R. Hamdi, ‘The effect of facets reflectivity on the static characteristics of (DFB) semiconductor laser’, in 2018 International Conference on Electrical Sciences and Technologies in Maghreb (CISTEM) , Oct. 2018, pp. 1–4

DFB_laser_model.icp (362.7 KB)

Hello @keshia.mekemezaona,

Sorry for the slow reply. It looks like the carrier density at this current with these settings is not reaching the carrier density at transparency, which is why the output just looks like noise. In general it seems like the settings used in this paper are fairly similar to the settings in our DFB laser example, except for the recombination coefficients.

I don’t have access to that paper so I can’t check to make sure their model is the same as ours, but I noticed that the gain compression factor in your file is off by a few orders of magnitude. It should be 5e-23 m^3 (note that you can also change the units for the TWLM element to cm^3 to match the paper).

In this table three coupling coefficients are listed. Do you know which was used to get this result?