We report generation of near-infrared photon pairs in fundamental spatial
modes via type-II spontaneous parametric down-conversion in a periodically
poled potassium titanyl phosphate (KTiOPO4) nonlinear waveguide supporting
multiple transverse modes. This demonstrates experimentally a versatile scheme
for controlling the spatial characteristics of the produced nonclassical light
based on exploitation of intermodal dispersion. The down-converted photons are
characterized by the measurement of the beam quality factors in the heralded
regime.Comment: 4 pages, 3 figures. To appear in Optics Letter
