A new mechanism for continuous-wave two-photon amplification

Summary form only given.A less well understood regime of quantum optical systems is the case when they are far from equilibrium and highly nonlinear. One device that inherently operates in this regime is the two-photon laser that is based on the two-photon-stimulated emission process, whereby two photons stimulate the emission of four photons. Such lasers are predicted to have highly unusual nonlinear dynamic and quantum statistical behaviors. Recently, our group demonstrated large continuous-wave two-photon amplification in a laser-driven potassium vapor based on a multiphoton Raman scattering process. Subsequent studies have revealed that destructive interference between multiple quantum pathways significantly reduces the two-photon-stimulated emission rate for this process. To overcome this problem, we have devised a new mechanism for two-photon amplification that suppresses the quantum interference using electromagnetically induced transparency in conjunction with a novel geometry.