Tomographic characterization of OPO sources close to threshold

Pattern function quantum homodyne tomography (QHT) has been used for characterizing the ouput of a degenerate below-threshold type-I OPO. The recovered photon number distributions deviated from those relative to Gaussian thermal states. The Kurtosis of the homodyne data confirmed these deviations, thus proving the power of QHT to highlight unexpected features of quantum states. © 2005 Optical Society of America.