In this paper, we describe experimental observation and characterization of emission of photons pairs through FWM in a silica nanofiber, with high Coincidence to Accidental Ratio (at best greater than 20000 in the CW regime at pump power 24mW and 40000 in the pulsed regime at pump around 150µW) and high pair emission rate (above 1MHz in the pulsed regime with CAR around 100 at a pump power around 7mW), despite residual presence of Raman spontaneous scattering (in the vicinity of the 12 th silica Raman band) on the Idler side. Moreover, these pairs of photons are observed with either single longitudinal mode source or a multimode source (as well as a pulsed source) showing a factor of two increase of emission rate with the multimode source thanks to its random temporal fluctuation coupled to the quadratic response of FWM.