A coherent, entangled photon source which uses a continuous wave laser to replace pulsed photon excitation sources in multiphoton nonlinear processes. In various embodiments, the device comprises a continuous wave photon laser creating electromagnetic radiation at a specific frequency and narrow linewidth. The emitted beam may be conditioned by an optical fiber to allow for efficient interaction with a nonlinear crystal. The nonlinear material is designed and fabricated in a specific manner, enabling the quantum mechanical process of a single photon with well-defined energy being converted into two or more photons which display quantum correlations. The nonlinear material and subsequent fiber-optic or free space components control the temporal, spatial, and polarization-related quantum correlations such that the entangled photons can create a signal in multiphoton nonlinear processes that is the same or exceeds that of a pulsed photon source but at the average and peak powers of a continuous wave laser.