gregmoille / pyLLE

Lugiato Lefever Equation Solver in Python/Julia
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A question about the simulation length "Tscan" #33

Open llllrrrrrr opened 2 years ago

llllrrrrrr commented 2 years ago

We have some questions about one of the parameters, Tscan. How is this value determined? When we changed it (up or down), we found that it made a big difference to the results, and there was no such amount in the actual experiment, so we didn't know what the basis for the adjustment was. We would appreciate it if you could answer us at any time! :)

gregmoille commented 2 years ago

The Tscan parameter is to define the scan time with respect in unit of round trip time. The numerical result are expected to be different for different Tscan for several reason:

  1. The soliton number one reach is stochastic. If you keep the exact same parameter you should get the same result yet if one slight change occur you might end up with a different behavior to reach solitonic stage. Yet if if you are slow enough to be adiabatic, the soliton behavior once reached should be the same.
  2. This also control the adiabaticity. The faster the scan is, the faster the detuning ramp is. If your detuning ramp is too fast, you might not be adiabatic anymore and reach weird behavior. So there is a trade off between too fast, and too long of a simulation

I hope this helps

llllrrrrrr commented 2 years ago

Thanks for your answer, we understand that Tscan with the tuning range can control the laser tuning rate together . However, we still have some doubts:

  1. You said that considering adiabatic, the speed should not be too fast. If the simulation time is not taken into account, will the slower speed be more friendly to the simulation results? We increased the Tscan in the case that we originally have a soliton state, but there is no single-soliton any more, should we use the smaller Tscan or continue to increase?

  2. If other parameters such as power and dispersion remain unchanged, and we use different tuning speeds (changing Tscan and tuning range) to reach the single soliton stage, should the corresponding optical frequency comb be the same?

Thanks again for your kind answer, it helped us a lot!