  Parametric amplifiers have allowed breakthroughs in ultrafast, strong-field,
and high-energy density laser science and are an essential tool for extending
the frequency range of powerful emerging diode-pumped solid-state laser
technology. However, their impact is limited by inherently low quantum
efficiency due to nonuniform light extraction. Here we demonstrate a new type
of parametric amplifier based on hybridized nonlinear optics. Hybridization of
parametric amplification with idler second harmonic generation induces unusual
evolution dynamics for a fully parametric amplifier - with saturating rather
than cyclic gain - observed here for the first time. This allows highly uniform
light extraction enabling unprecedented efficiency for a lossless amplifier
with Gaussian-like intensity profiles - a 48-dB single-stage gain with 68%
quantum efficiency and 44% pump-to-signal energy conversion - a several-fold
improvement over the standard. Possessing both laser-like high quantum
efficiency and the advantages of thermal-loading free parametric systems, this
simple approach can be implemented widely and have significant impact by
increasing several-fold the power available for science and industry.
