  We propose a method for generation of entangled photonic states in high
dimensions, the so-called qudits, by exploiting quantum correlations of Orbital
Angular Momentum (OAM) entangled photons, produced via Spontaneous Parametric
Down Conversion. Diffraction masks containing $N$ angular slits placed in the
path of twin photons define a qudit space of dimension $N^2$, spanned by the
alternative pathways of OAM-entangled photons. We quantify the high-dimensional
entanglement of path-entangled photons by the Concurrence, using an analytic
expression valid for pure states. We report numerical results for the
Concurrence as a function of the angular aperture size for the case of
high-dimensional OAM entanglement and for the case of high-dimensional path
entanglement, produced by $N \times M$ angular slits. Our results provide
additional means for preparation and characterization of entangled quantum
states in high-dimensions, a fundamental resource for quantum simulation and
quantum information protocols.
