Generation of telecom-band correlated photon pairs in different spatial modes using few-mode fibers

We experimentally demonstrate the production of photon pairs at 1555 nm in LP01 mode and at 1566.8 nm in LP11 mode, respectively, via the spontaneous intermodal four-wave mixing in a 100-m-long few-mode fiber. We achieve a coincidence to accidental-coincidence ratio of 28, which clearly indicates the existence of quantum correlation. We also discuss the contribution of spontaneous Raman scattering to the background noise of photon pairs. Our source of photon pairs, compatible with the low-loss multiplexing and de-multiplexing components for space division multiplexing optical fiber communication, can be used for generating higher-dimensional entanglement.