Abstract

The degenerate parametric oscillator is an important source of squeezed light. If the pump mode is adiabatically eliminated, its operation is governed by two dimensionless parameters: the pump parameter λ and the coupling constant g. The pump parameter controls the threshold behavior predicted by semiclassical theory (threshold is reached for λ = 1). The coupling constant g determines the strength of the quantum fluctuations. The optical parametric oscillators used to generate squeezed light have g ~ 10^–4 ≪ 1.¹ Therefore, in these systems the quantum fluctuations only produce very small perturbations about semiclassical states. We have recently shown how the steady state of the degenerate parameter oscillator changes as a function of coupling strength.² In the strong coupling limit, major departures from semiclassical states occur; for g² ≫ 1 and 2λ²/g² ≪ 1 the steady state approches the coherent state superposition $|{\psi }_{+}〉=|\sqrt{\text{λ}/g}〉+|-\sqrt{\text{λ}/g}$.

© 1989 Optical Society of America