Squeezing and Einstein-Podolsky-Rosen correlation in the mirrorless optical parametric oscillator

This work analyses the quantum properties of counterpropagating twin beams generated by a mirrorless optical parametric oscillator in the continuous-variable regime. Despite the lack of the filtering effect of a cavity, we show that in the vicinity of its threshold it may generate high levels of narrowband squeezing and Einstein-Podolsky-Rosen correlation, completely comparable to what can be obtained in standard optical parametric oscillators.