  Light with orbital angular momentum (OAM) has great potentials in both
classical and quantum optical communications such as enhancing the transmission
capacity of a single communication channel because of its unlimited dimensions.
Based on OAM conservation in second order nonlinear interaction processes, we
create a classical to quantum optical network link in OAM degree of freedoms of
light via sum frequency generation (SFG) following by a spontaneous parametric
down conversion (SPDC). A coherent OAM-carrying beams at telecom wavelength
1550nm is up-converted to 525.5nm OAM-carrying beams in the first crystal, then
up-converted OAM-carrying beam is used to pump a second crystal to generate
non-degenerate OAM entangled photon pairs at 795nm and 1550nm. By switching the
OAM carries by the classical party, the OAM correlation in the quantum party is
shifted. High OAM entanglements in two dimensional subspaces are verified. This
primary study enables to build a hybrid optical communication network contains
both classical and quantum optical network nodes.
