Ultra-broadband optical parametric generation in periodically poled stoichiometric LiTaO_3

We report on broadband gain in an optical parametric generator based on periodically poled 1 mol% magnesium-doped stoichiometric LiTaO3 (PPMg:SLT). More than an octave-spanning parametric gain, stretching from near to mid-infrared, is generated by pumping the crystals close to the point where, at parametric degeneracy, the waves experience zero group-velocity dispersion. Using a picosecond Ti:sapphire source, we measured the broadest parametric gain bandwidths, 180 THz at 10 dB, in PPMg:SLT gratings with a period of 25 µm pumped at 860 nm.