Teja J, Wong N
Opt Express. 1998 Feb 2;2(3):65-71. doi: 10.1364/oe.2.000065.
We demonstrate a low-threshold twin-beam generator using a cw triply resonant optical parametric oscillator consisting of two coupled cavities: one that resonates the signal and idler waves and the other the pump field. An intensity correlation of 5.5 dB was observed at 3 MHz for a type-II phase-matched KTP optical parametric oscillator.