We demonstrate a hybrid approach to detecting a short fringe period of two-photon interference with high brightness, by combining spontaneous parametric down-conversion (SPDC) and up-conversion techniques. Photon pairs were generated at the wavelength of 1550 nm via SPDC, and converted to 516.7 nm through up-conversion process with the pump light 775 nm in efficiency ∼90%. The two-photon interference of the up-converted photon pairs exhibited a fringe period of 258.3 nm with high event rate (∼2000 counts s−1), which was 6 times shorter than the original wavelength, demonstrating that the energy-time correlation of the photon pairs was preserved. The technique simultaneously provides short fringe period beyond the classical limit and high brightness of the photon pairs.
- photon pairs
- two-photon interference