This study demonstrates a versatile entanglement source in the telecom band for fiber-based quantum internet. The source features a narrow linewidth (sub-MHz), high entanglement fidelity (>95%), and Bell-state generation even with frequency multimode. Two-photon correlation is observed after 20 km of fiber distribution, despite the limited bandwidth of the wavelength converter. This approach is promising for efficient entanglement distribution compatible with quantum memory and frequency-multiplexed long-distance quantum communication.
