Theory of a synchronously-pumped aperiodically-poled OPO

Summary form only given. In a recent paper, Beddard et al. (2000) reported the generation of 5-cycle pulses at 3 /spl mu/m in a synchronously-pumped OPO based on aperiodically-poled lithium niobate (APPLN). In the paper, we report a parallel computational study of the problem that reveals the key elements and processes involved in the nonlinear interaction. While a theoretical analysis of second harmonic generation using APPLN has previously been reported this is to our knowledge the first such study for an OPO. The full coupled wave equations are solved for pump, signal and idler, taking full account of aperiodic poling, frequency chirping, dispersion in the crystal (to all orders), dispersion compensation and pump period tuning. To match the experiment, the central pump wavelength was chosen as 840-nm, the pump duration was 45 fs, and the grating period varied linearly from 22.0 /spl mu/m to 23.54 /spl mu/m.