any one can help me

[alihashemi7272]

respectfully,

I have a problem to use this code for my structure. i have used split step method for solving nonlinear schrodinger equation written by dudley 2010 in Matlab.

I convert the complex time-domain at last raw to npz files. then run the python codes but the output right figure has stopped at zero frequency. the input wavelength for my structure is about 6 micrometer. there is a mismatch frequency between AT Matlab output and Et input python codes. what is the difference between them?

So, I would ask you please guide me the implementation & figure drawing codes of spectrogram, if may. I'll be gratitude if you consider and reply me.

I'am eagerly seeking your response.

Thanks in advance. Sincerely yours Ali

[omelchert]

Dear Ali,

the optfrog utility is designed to work for the analytic signal related to the real optical field. This involves the actual optical angular frequency in terms of an unidirectional propagation approach for which negative frequencies are omitted.

In contrast, the nonlinear Schroedinger equation (NSE) introduces the concept of a carrier frequency and involves a frequency detuning relative to that carrier frequency.

So, by using the optfrog-utility in a naive way, you omit the negative frequencies. This is correct for the propagation method for the analytic signal, while is does not directly carry over to the NSE (so, your negative frequency detunings appear to be cut off).

There are several possibilities to proceed:

(1) shift and zero-pad your signal to represent the actual optical
frequency and use the optfrog utility as is, or

(2) send me your data that produced the figure you enclosed (i.e. your
input data to the optfrog utility and script you used to produced the figure). I have a concise python script that generates spectrograms for data generated using a NSE employing frequency detunings. However, I am quite busy and it
might take until monday to respond.

Best, O

Quoting alihashemi7272 notifications@github.com:

respectfully,

I have a problem to use this code for my structure. i have used split step method for solving nonlinear schrodinger
equation written by dudley 2010 in Matlab.

I convert the complex time-domain at last raw to npz files. then run
the python codes but the output right figure has stopped at zero
frequency. the input wavelength for my structure is about 6
micrometer. there is a mismatch frequency between AT Matlab output
and Et input python codes. what is the difference between them?

So, I would ask you please guide me the implementation & figure
drawing codes of spectrogram, if may. I'll be gratitude if you
consider and reply me.

I'am eagerly seeking your response.

Thanks in advance. Sincerely yours Ali

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