  We present the full experimental reconstruction of Gaussian entangled states
generated by a type--II optical parametric oscillator (OPO) below threshold.
Our scheme provides the entire covariance matrix using a single homodyne
detector and allows for the complete characterization of bipartite Gaussian
states, including the evaluation of purity, entanglement and nonclassical
photon correlations, without a priori assumptions on the state under
investigation. Our results show that single homodyne schemes are convenient and
robust setups for the full characterization of OPO signals and represent a tool
for quantum technology based on continuous variable entanglement.
