Non-linear and quantum optics of a type II OPO containing a birefringent element Part 1: Classical operation

We describe theoretically the main characteristics of the steady state regime of a type II Optical Parametric Oscillator (OPO) containing a birefringent plate. In such a device the signal and idler waves are at the same time linearly coupled by the plate and nonlinearly coupled by the χ crystal. This mixed coupling allows, in some well-defined range of the control parameters, a frequency degenerate operation as well as phase locking between the signal and idler modes. We describe here a complete model taking into account all possible effects in the system, i.e. arbitrary rotation of the waveplate, non perfect phase matching, ring and linear cavities. This model is able to explain the detailed features of the experiments performed with this system. PACS. 42.65.-k Nonlinear optics – 42.65.Yj Optical parametric oscillators and amplifiers – 42.60.Fc Modulation, tuning, and mode locking – 42.25.Lc Birefringence