A continuous-wave photon-pair source operating in L-band through spontaneous four-wave mixing in birefringent ZBLAN fiber

A continuous-wave (CW) photon-pair source operating in the L-band was successfully realized based on spontaneous four-wave mixing (SFWM) by using short length of a birefringent ZBLAN fiber. A type-III phase-matched SFWM process was utilized by pumping a birefringent ZBLAN fiber with pump photons polarized along the slow axis, where signal and idler photons were generated with polarizations aligned to the vertical axis of the birefringent ZBLAN fiber. The phase-matching curve was calculated, and the joint spectral intensity was analyzed under 1310 nm pumping conditions. Then, we experimentally generated signal and idler photons with center wavelengths of 1117 and 1578 nm using a 1310 nm CW laser as a pump light source and measured their quantum optical properties. The maximum coincidence-to-accidental ratio was calculated to be 22, resulting in a photon-pair brightness of 3.16 × 10⁴ pairs/s/nm/mW. The results show the feasibility of using ZBLAN fibers in quantum optics as an efficient platform for generating a quantum light source.