metric Oscillator - Beckman Institute Laser Resource Center

An OPO works in the reverse fashion in which the energy contained in apump photon at frequency Op is transferred to two other photons as (the signal wave)and 0; (the idler wave) in such a way as to satisfy the energy conversion law:Or, in terms of wavelength:By placing the parametric gain medium (I3BO) in an appropriate resonantcavity, oscillation at the signal andlor idler wavelength can be obtained. In OPOs,the gain can be large enough that no signal input wave is necessary. the signal willgrow from quantum noise in the crystal. Both the signal wave and the idler wave canbe resonated simultaneously (doubly resonant), or individually (singly resonant). TheQuanta-Ray MOPO-700 series is designed such that both cavities ( that is the masterand power oscillator ) are singly resonant over the signal wavelength range.Pump Beam3% VariableUs 410-690 nrn (signal)Wi 730-2000 nrn (idler)tP- -6Figure 1-2: Parametric Amplification to Generate Tunable Output from 410nm to Beyond 2000nm.The output of an OPO is very similar to that of a laser. The signal andidler beams exhibit strong coherence, are highly monochromatic, and have a spec- \--?==k=,trum consisting of one or more longitudinal modes. Although similar in structure andoperation to that of a laser, the OPO obtains gain from a nonlinear conversion ratherthan an atomic transition. Because of this difference, the OPO has no gain storage,Ir-- -and thus only operates when the pump wave is present.L