Abstract
We study the squeezing properties of the second-harmonic mode of a degenerate parametric oscillator coupled to an independent two-mode squeezed vacuum reservoir employing the linearization procedure. It is found that for the second-harmonic mode the cavity radiation exhibits squeezing even when coupled to a vacuum reservoir. Moreover, coupling the oscillator to the squeezed vacuum reservoir enhances the degree of squeezing exponentially. For the output radiation the correlation of the quadrature operators evaluated at different times also exhibits squeezing, which is the reason for quenching of the overall noise in one of the quadrature components of the fundamental mode irrespective of the squeeze parameter of the reservoir.