Singly resonant cavity-enhanced frequency tripling

We use a plane-wave analysis to examine a singly resonant, cavity-enhanced, frequency doubler containing an intracavity sum-frequency interaction that frequency sums the resonant fundamental with the second harmonic to produc e the third harmonic of the resonant field. We derive expressions for the s teady-state performance of the device. We determine the input coupler inten sity reflectivity and the ratio of nonlinear drives between the second-harm onic generation (SHG) and sum-frequency generation (SFG) stages for optimum third-harmonic conversion efficiency. We also examine the optimum SHG inte raction length under conditions of limited total interaction length. We fin d that numerical simulations modeling three spatial dimensions can be close ly approximated by appropriately scaled plane-wave results. As an example, we consider frequency tripling of a 350-mW, 1319-nm, cw laser in two consec utive nonlinear gratings in periodically poled Lithium niobate and iind thi rd-harmonic power-conversion efficiency of 85.3% when first-order quasi-pha se-matching (QPM) is used for the SFG process and 51.0% when third-order SF G QPM is used. We also consider frequency tripling of a 20-W, 1064-nm, cont inuous-wave mode-locked laser in two lithium triborate crystals and find a time-averaged third-harmonic power-conversion efficiency of 56.0% from mode ling three spatial dimensions. (C) 1999 Optical Society of America [S0740-3 224(99)01403-4]. OCIS codes: 190.0190, 190.7220, 190.4360.