Scattering of pumping radiation in the backword direction that is caused by initiation of stimulated Brillouin scattering (SBS) nonlinearity in the gain medium;
As mismatch between the states of polarization of the input signal and the pumping radiation can directly impact FWM and, therefore, also the idler generation process, it was decided to analyse gain polarization dependence of parametric amplifiers before estimating the impact of FOPA pump-phase modulation on the idler spectral components.
While obtaining the dependence of idler generation efficiency on the mutual mismatch of the states of polarization between the signal and the pumping radiation, it was decided to simplify the simulation model as much as possible to avoid impact of other factors on the obtained results.
The most effective way to suppress SBS is to modulate the phase of the pumping radiation, in such a wa broadening its spectrum .
075 center frequency, 650 GHz -3 dB two-sided bandwidth) at the output of the amplifier were chosen in a way to filter out the signal and the pumping radiation, thus letting through only the idler spectral components.
Phase modulation of the pump was required in order to broaden the spectrum of the pumping radiation, in such a way mitigating the impact of stimulated Brillouin scattering.
78 THz, in order to suppress the pumping radiation and the idler spectral components that were produced in the HNLF during the process of amplification.
The same pump wavelength as mentioned above was used to find the most appropriate power of the pumping radiation.
It also can be seen, that the level of the pumping power is high enough to generate third order spectral components, so a small part of the pumping radiation was lost due to generation of these parasitic harmonics.