Femtosecond Traveling-Wave Optical Parametric Amplification in MgO:LiNbO(3)

Highly efficient optical parametric amplifier tunable from near- to mid-IR for driving extreme nonlinear optics in solids

We have developed a robust optical parametric amplifier (OPA) based on three-AgGaS₂-crystal pumping by a Cr:Forsterite GW femtosecond laser system, generating 150 fs pulses in dual bands of 1.6-2.0 μm (signal wave) and 3.5-5.5 μm (idler wave). By introducing a negative prechirp to the pump, a combined efficiency in two waves of greater than 10% was achieved, with signal energy up to 110 μJ and idler energy up to 43 μJ. Operation parameters of the system (intensity up to 90  TW/cm²) make OPA a promising tool for driving nonlinear optical phenomena, including generation of optical harmonics and laser-induced extreme states of matter in solids and liquids. As a proof of principle, we generated harmonics up to the sixth order and sum frequencies in 5 mm thick polycrystalline ZnSe.

Mercury thiogallate mid-infrared femtosecond optical parametric generator pumped at 1.25 microm by a Cr:forsterite regenerative amplifier

We demonstrate a novel traveling-wave-type optical parametric generator based on 1.25-microm pumping of HgGa(2)S(4) that produces tunable, high-power, transform-limited infinity 200-fs pulses in the mid-IR from 5 to 9 microm. Output idler energies on the microjoule level are obtained with maximum conversion efficiency of 11% for the amplifier stage, which is more than two times better than the results obtained with an analogous sample of the widely spread material AgGaS(2).

Efficient femtosecond traveling-wave optical parametric amplification in periodically poled KTiOPO(4)

We report, for the first time to our knowledge, high-power femtosecond traveling-wave optical parametric amplification by use of periodically poled KTiOPO(4) . With a single pass through a 4-mm-long sample of 1.23-mm thickness we achieved 40% internal conversion efficiency and 5microJ of single-pulse idler energy near 3.8microm , using only 75microJ of energy from the output of a conventional 1-kHz Ti:sapphire regenerative amplifier. The 210-fs-long idler pulses were almost transform limited. We discuss the specific problems encountered in high-power parametric conversion, such as unwanted quasi-phase-matched upconversion processes for polarization configurations that utilize the largest (d(33)) nonlinear coefficient and the related formation of color centers (gray tracking) in KTiOPO(4) .

Femtosecond parametric generation in ZnGeP(2)

We report traveling-wave optical parametric generation in short (2-mm) ZnGeP(2) samples with reduced anomalous absorption, using femtosecond pump pulses near 2 mum . The signal and the idler waves generated could be tuned from 2.5 to 10 mum , and they extend the tunability of the beta-barium borate optical parametric generator used as a pump source to the mid-infrared. At a single-pass internal conversion efficiency of 2.5% we estimate pulse durations of 75 fs (signal near 3 mum) and 200 fs (idler near 6 mum).