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 (λ = 1475 nm) and idler (λ = 3820 nm) waves in the superluminescence regime is ∼120 mW (peak power ∼120 kW). The maximum total conversion efficiency with respect to the absorbed power in the superluminescence regime is ∼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 ∼30 and ∼60 mW at degrees of pump depletion of 47% and 55% for the superluminescence and singly resonant OPO regimes, respectively.