In this Letter, the generation of 1.5 {\mu}m discrete frequency entangledtwo-photon state is realized based on a piece of commercial polarizationmaintaining fiber (PMF). It is connected with a polarization beam splitter torealize a modified Sagnac fiber loop (MSFL). Correlated two-photon states aregenerated through spontaneous four wave-mixing process along the twopropagation directions of the MSFL, and output from the MSFL with orthogonalpolarizations. The quantum interference of them is realized through a 45{\deg}polarization collimation between polarization axes of PMFs inside and outsidethe MSFL, while the phase difference of them is controlled by the polarizationstate of the pump light. The frequency entangled property of the two-photonstate is demonstrated by a spatial quantum beating experiment with a fringevisibility of (98.2+/-1.3)%, without subtracting the accidental coincidencecounts. The proposed scheme generates 1.5 {\mu}m discrete frequency entangledtwo-photon state in a polarization maintaining way, which is desired inpractical quantum light sources.
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