  A frequency-multiplexed entangled photon pair and a high-dimensional
hyperentangled photon pair are useful to realize a high-capacity quantum
communication. A biphoton frequency comb (BFC) with entanglement can be used to
prepare both states. We demonstrate polarization entangled BFCs with over 1400
frequency modes, which is approximately two orders of magnitude larger than
those of earlier entangled BFCs, by placing a singly resonant periodically
poled LiNbO3 waveguide resonator within a Sagnac loop. The BFCs are
demonstrated by measuring the joint spectral intensity, cross-correlation, and
autocorrelation. Moreover, the polarization entanglement at representative
groups of frequency modes is verified by quantum state tomography, where each
fidelity is over 0.7. The efficient generation of a massive-mode entangled BFC
is expected to accelerate the increase of capacity in quantum communication.
