Engineering the spectral profile of photon pairs by using multi-stage nonlinear interferometers

Using the quantum interference of photon pairs in N-stage nonlinear interferometers (NLIs), contour joint spectral function can be modified into an islands pattern. We perform two series experiments. One is that all fibers pulse pumped NLIs are identical; other lengths N pieces different. not only demonstrate how pattern changes with stage number N, but also characterize relative intensity island peaks varies N. The results well agree theoretical predictions, revealing NLI following binomial distribution provide a better active filtering function. Our investigation shows effect multi-stage useful tool for efficiently engineering factorable two-photon state—a desirable resource information processing.