  We study the generation of correlated photon pairs and heralded single
photons via strongly non-degenerate spontaneous four-wave mixing (SFWM) in a
series of identical micro-/nano fibers (MNF). Joint spectral intensity of the
biphoton field generated at the wavelength of about 880 nm and 1310 nm has been
measured under excitation by 100 ps laser pulses demonstrating good agreement
with the theoretical prediction. The measured zero-time second-order
autocorrelation function was about 0.2 when the emission rate of the heralded
photons was of 4 Hz. The MNF-based source perfectly matches standard
single-mode fibers, which makes it compatible with the existing fiber
communication networks. In addition, SFWM observation in a series of identical
MNFs allows increasing generation rate of single photons via spatial
multiplexing.
