Parametric generation in a PPLN crystal pumped by a Q-switched mode-locked Nd : YAG laser: comparison of the superluminescent and singly resonant operation regimes

The output characteristics of light in two parametric generation regimes [parametric superluminescence and parametric generation in a singly resonant optical parametric oscillator (OPO) based on a 50-mm long PPLN crystal, synchronously pumped by a 50-ps Nd : YAG laser] are compared. The total average output power at the wavelengths of signal (lambda = 1475 nm) and idler (lambda = 3820 nm) waves in the superluminescence regime is similar to 120 mW (peak power similar to 120 kW). The maximum total conversion efficiency with respect to the absorbed power in the superluminescence regime is similar to 60%. The maximum conversion efficiency into the idler wave with respect to the absorbed pump power is 15% and 25% (quantum efficiencies of 54% and 90%) for the superluminescence and singly resonant OPO regimes, respectively. The maximum values of the average output power at the idler wavelength are similar to 30 and similar to 60 mW at degrees of pump depletion of 47% and 55% for the superluminescence and singly resonant OPO regimes, respectively.