A section of SMF introduces a time-delay, thus for different input optical wavelengths, different spectral phases ought to be introduced. In order to demonstrate this phenomenon, I tried two simulation experiments (a and b in attached file 1), but both failed.
Experiment a: a1) and a2) use the same SMF (0.01km, disabled GVD), and the same laser diode except for different frequencies.
a1) LD: fre=193.1THz，linewidth=0，initial phase=0
after SMF transmission, measured spectral phase=1.37rad @193.1THz
a2) LD: fre=193.11THz，linewidth=0，initial phase=0
after SMF transmission, measured spectral phase=1.37rad @193.11THz
As additional spectral phase=SMF group delay*input optical frequency, and SMF group delay is around the same, for different input optical wavelengths, why do they have the same spectral phase?
Experiment b: SMF length=1 m
As the refraction index of fiber core is around 1.5, a time delay of around 5-ns ought to be introduced after 1-m SMF transmission. For comparison, the input and output optical pulses are presented in attached file 2. As can be seen, no time delay exists between two pulse trains.
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