Tunable cavity-enhanced photon pairs source in Hermite-Gaussian mode

The spatial modes of light have grasped great research interests because of its great potentials in optical communications, optical manipulation and trapping, optical metrology and quantum information processing. Here we report on generating of photon pairs in Hermite-Gaussian (HG) mode in a type-I optical parametric oscillator (OPO) operated far below threshold. The bandwidths of the photon pairs are 11.4 MHz and 20.8MHz for two different HG modes respectively, which is capable to be stored in cold Rubidium atomic ensembles. From correlation measurements, non-classical properties of HG modes in different directions are verified by tuning the cavity. Our study provides an effective way to generate photon pairs with narrow bandwidth in high order spatial modes for high dimensional quantum communication. In modern optical science, the spatial degree of freedom of photon has grasped great research interests for its wide applications in many fields including optical communications [1-3], optical manipulation and trapping [4], optical metrology [5-7] and quantum information processing [8-12], etc. Quantum information processing benefits greatly from improved manipulation of different photonics degrees of freedoms [13, 14]. Various studies of photon’s spatial degree of freedoms are motivated that such modes can increase greatly the information carried by photons [15-18]