Bright narrowband photon pairs generated in an intra-cavity 2N walk-off compensating configuration

We studied theoretically the influence of the walk-off effect on the spectral brightness of the type-I cavity-enhanced spontaneous parametric down-conversion. The results show that the spectral brightness of the generated entangled photon pairs can be improved significantly by using a 2N walk-off compensating configuration, in which N pairs of nonlinear crystals with their walk-off angles of opposite signs are stacked and bonded in sequence along the propagation direction. The spectral brightness of the entangled photon pairs are expected theoretically to be 1.27×105 pairs/(smWMHz) for N = 4 with a submegahertz bandwidth in a triple-resonant cavity configuration. Our results provide a solid theoretical basis for the generation of entangled photon-pair sources of high spectral brightness and narrow bandwidth, which may have potential applications in quantum technology. •We study the spectral brightness of photon pairs in an intra-cavity configuration.•The influence of the walk-off effect on the spectral brightness is investigated.•The brightness can be enhanced by combining the 2N walk-off compensating scheme.