Multimode squeezed light generation in a three-plane-mirror confocal cavity

In this paper, we propose a kind of degenerate optical parametric oscillator below threshold and use the thin crystal approximation to analyze the quantum noise reduction of the spectrum emitted from this cavity, and get the relation between the squeezing level and the pump field or the cavity detuning. We found that better squeezing level could be obtained only by properly choosing the phase of the local field, the amplitude of the pump field and the cavity detuning of the confocal cavity