Cylindrical KTiOPO4 crystal for enhanced angular tunability of phase-matched optical parametric oscillators

We demonstrate what is to our knowledge the first optical parametric oscill ator (OPO) based on a cylindrical phase-matched nonlinear crystal. Experime nts are performed with an uncoated KTiOPO4 crystal cut as a cylinder with a diameter of 21.2 mm and a thickness of 5 mm. We achieve 29.5-internal-degr ee angular tuning in a 1064-nm-pumped type III OPO, which would correspond to similar to 36 degrees external angular rotation for a parallelepipedal c rystal. The goals of using such a device are to narrow the spectral width o f the output and to enhance the spatial quality of the generated beams in w idely tunable OPO's. (C) 2000 Optical Society of America.