Synchronously pumped optical parametric oscillator with intracavity difference-frequency mixing

n this work we experimentally investigate a singly resonant optical parametric oscillator (OPO) with an intracavity crystal that mixes the signal and idler waves, enhancing the power conversion efficiency of the idler radiation.;Extra-cavity difference-frequency mixing (DFM) of the signal and idler from an OPO has been demonstrated and recently investigators have examined mixing the signal and idler waves from a synchronously pumped OPO to produce long-wavelength difference-frequency radiation. Here the difference-frequency ;Recently the advantages of carrying out a DFM process inside an OPO cavity resonant at the signal frequency were reported. Operation at high conversion efficiency occurs over a large dynamic range of incident pump intensity for proper choices of the ratio of the coupling parameters of the OPO and DFM processes. This large dynamic range is expected to improve the conversion efficiency when the pump beam has transverse or temporal intensity variations. The pump radiation is converted into signal and idler radiation in the OPO interaction, and signal radiation is converted into idler and difference-frequency radiation in the DFM interaction. Except near threshold, most of the signal radiation generated in the OPO process is down-converted by the DFM process. In the ideal case where the OPO process heavily depletes the pump radiation, photon-conversion efficiencies for generation of idler and difference-frequency radiation can be close to ;Experimental work has produced a maximum idler photon-conversion efficiency of 1.15. The idler photon-conversion efficiency of the OPO with intracavity DFM is an 80% increase as compared to the simple OPO without the intracavity DFM interaction. It is demonstrated that the additional idler power comes at the expense of resonated signal radiation and increased pump depletion. The maximum idler photon-conversion efficiency corresponds to the generation of 6.3 W of idler power for 18.0 W of pump power. This gives an idler power conversion efficiency of 35% which is greater than the theoretical limit of 31% for the simple OPO. (Abstract shoretened by UMI.);Optical parametric oscillators provide a method for producing coherent tunable radiation from a coherent fixed-frequency pump source. The pump frequency...