ABSTRACT
Nondegenerate four-wave-mixing (fwm) is a process by which one or two pump fields generate two signal beams, with conservation of the total photon energy and momentum. The signal beams can be distinguished by their frequency, or by their wave vector, or by their polarization. When the nonlinear medium which creates the fwm process is contained in a resonant cavity, the signal generation is caused by an instability, because the signal fields experience gain (fwm gain), and when this gain overcomes the cavity losses the signal beams build up. This chapter discusses several static and dynamical instabilities which arise from nondegenerate fwm. It considers a cavity with plane mirrors and examines the properties of quantum noise reduction which arise in the intensity difference between the signal beams generated by the fwm process. The chapter illustrates the problem of Gauss-Laguerre transverse modes in a ring cavity with spherical mirrors.
