Abstract:
Highly efficient (quantum efficiency 17%) parametric superradiance was generated in a nonlinear ZnGeP2 crystal of length 4.2 cm pumped by single (of energy ~1 mJ) ultrashort pulses (τ = 150 psec) from an erbium laser (λ = 2.79 µ). High-power (~1 MW) continuously tunable infrared radiation of wavelengths 5–5.3 and 5.9–6.3 µ was obtained. The energy and angular tuning characteristics, line width, divergence, and gain of this superradiance were determined. The nonlinear coefficient d36 was found for ZnGeP2. Depletion of the laser pumping had to be allowed for already for parametric superradiance efficiency of just 0.1%.