Optical parametric generation in periodically poled $KTiOPO4$ via extended phase matching

We report an experimental demonstration of optical parametric generation in a periodically poled $KTiOPO4$ crystal based on the principle of mirrorless optical parametric oscillation. A femtosecond pump pulse spectrally centered at $792nm$ from a Ti:sapphire amplifier is prechirped to minimize Kerr effects. The pump pulse is then injected into the nonlinear crystal and down converted to signal and idler pulses, approximately centered at $1584nm$⁠, via amplified spontaneous parametric down conversion in a copropagating type-II quasiphase matching configuration. The maximum internal downconversion efficiency is 43%, the highest ever reported for optical parametric generators based on $KTiOPO4$ crystals. Such a device may find applications in optical signal processing and biological imaging.