Broadly tunable noncollinear optical parametric oscillator with periodically poled KTiOPO 4

Abstract

Here we report on a noncollinear optical parametric oscillator (OPO) in periodically poled KTiOPO<SUB>4</SUB>. The noncollinear OPO cavity consisted of a 10 mm-long periodically poled KTiOPO<SUB>4</SUB> crystal placed between two flat mirrors and pumped at 532nm by a frequency doubled Q- switched Nd:YAG. The OPO threshold for the collinear configuration was reached at the pump pulse energy of 10 (mu) J and increased monotonically when increasing the noncollinear interaction angle. The efficiency of the OPO with PPKTP reached 50 percent in the collinear configuration and about 40 percent in the noncollinear configuration. The noncollinear OPO generated two signal-idler pairs. Only one of the waves in each pair was resonated in the OPO cavity, while the complementary waves were generated at different angels as required by momentum conservation. The OPO could be tuned over a range of about 290 nm around 1064 nm wavelength by adjusting the cavity angle and the PPKTP temperature. Narrowing of the OPO spectrum was observed for small noncollinear interaction angles.