Frequency entangled photon-pairs are widely used in quantum technologies such as quantum metrology
and quantum information processing. Increasing the bandwidth of frequency entangled photon-pairs is very important
because broadening the bandwidth improves the depth resolution of quantum optical coherence tomography,
enhances the efficiency of two-photon absorption, and extends the bandwidth of quantum communication. Ring
resonators can generate frequency entangled photon-pairs via four-wave mixing process and are expected to be used
as a photon source for integrated optical quantum circuits. We have constructed an ultra-broadband frequency filter
and investigated the generation of broadband frequency entangled photon-pairs using an on-chip ring resonator
made of high-index contrast doped glass.