Second-harmonic generation in zinc tris(thiourea) sulfate

The linear and second-order nonlinear optical properties of single-crystal zinc tris(thiourea) sulfate, or ZTS, are determined. The deduced nonlinear coefficients are |d31| = 0.31, |d32| = 0.35, and |d33| = 0.23 pm/V compared with a |d14| value of 0.39 pm/V for potassium dihydrogen phosphate. Because it exhibits a low angular sensitivity (δΔk/δθ), ZTS may prove useful for type-II second-harmonic generation from 1.06 to 1.027 μm. We present the phase-matching measurement data for ZTS and compare the calculated frequency conversion efficiency for ZTS with that of several other well-characterized materials.