Recently, a method of engineering the quantum states with a nonlinear interferometer was proposed to achieve precise state engineering for near-ideal single-mode operation and near-unity efficiency (L. Cui et al., Phys. Rev. A 102, 033718 (2020)), and the high-purity bi-photon states can be created without degrading brightness and collection efficiency. Here, we study the coarse or fine tunability of the nonlinear interference method to match constructive interference patterns into a transmission window of standard 100-GHz DWDM channels. The joint spectral intensity spectrum is measured for various conditions of the nonlinear interference effects. We show that the method has coarse- and fine-tuning ability while maintaining its high spectral purity. We expect that our results expand the usefulness of the nonlinear interference method. The photon-pair generation engineered via this method will be an excellent practical source of the quantum information process.
Supermode-based second harmonic generationin a nonlinear interferometer
