  We study the generation of correlated photon pairs via spontaneous four wave
mixing in a 15 cm long micro/nano-fiber (MNF). The MNF is properly fabricated
to satisfy the phase matching condition for generating the signal and idler
photon pairs at the wavelengths of about 1310 and 851 nm, respectively. Photon
counting measurements yield a coincidence-to-accidental ratio of 530 for a
photon production rate of about 0.002 (0.0005) per pulse in the signal (idler)
band. We also analyze the spectral information of the signal photons originated
from the spontaneous four wave mixing and Raman scattering. In addition to
discovering some unique feature of Raman scattering, we find the bandwidth of
the individual signal photons is much greater than the calculated value for the
MNF with homogeneous structure. Our investigations indicate the MNF is a
promising candidate for developing the sources of nonclassical light and the
spectral property of photon pairs can be used to non-invasively test the
diameter and homogeneity of the MNF.
