We suggest that closed-loop quadratic nonlinear waveguide arrays can be used as a compact interferometrically stable integrated source of discrete orbital-angular-momentum (OAM) entangled biphoton state. We describe analytically and numerically the process of biphoton generation through spontaneous parametric down-conversion in triangular waveguide arrays, and reveal that the generated biphoton quantum states can be precisely controlled by changing the pump phase and wavelength, including the case of photon-pair generation with pure OAM.

• Received 8 April 2013

DOI:https://doi.org/10.1103/PhysRevA.87.063814