  We compare the bipartite entanglement and EPR-steering properties of the two
different schemes which produce third harmonic optical fields from an input
field at the fundamental frequency. The first scheme uses second harmonic
cascaded with sum-frequency generation while the second uses triply degenerate
four-wave mixing, also known as direct third harmonic generation. We examine
and compare the two schemes in both the travelling wave and intra-cavity
configurations. We find that both schemes produce continuous-variable bipartite
entanglement and EPR-steering. The direct scheme produces a greater degree of
EPR-steering while the cascaded scheme allows for greater flexibility in having
three available bipartitions.
