Experimental Performance of a Two-Stage Periodically Poled Lithium Niobate Parametric Amplifier

A two-stage periodically poled lithium niobate parametric amplifier is used to boost the idler wave energy by almost a factor of three near the degenerate wavelength of the second stage. For nondegenerate values, the idler wave energy is boosted by a factor of two. Our experimental results validate a numerical model that includes arbitrary beam profiles, beam walkoff, pump depletion, and optical elements between crystals. Experimental performance of the whole system was found to be much more stable over a wide range of temperatures due to noncollinear phase-matching conditions in the second stage.