  In this work we analyse and compare the continuous variable tripartite
entanglement available from the use of two concurrent or cascaded $\chi^{(2)}$
nonlinearities. We examine both idealised travelling-wave models and more
experimentally realistic intracavity models, showing that tripartite entangled
outputs are readily producible. These may be a useful resource for such
applications as quantum cryptography and teleportation.
