Optical
Nonlinearity in Cu<sub>2</sub>CdSnS<sub>4</sub> and α/β-Cu<sub>2</sub>ZnSiS<sub>4</sub>: Diamond-like
Semiconductors with High Laser-Damage Thresholds
- Publication date
- Publisher
Abstract
Cu<sub>2</sub>CdSnS<sub>4</sub> and α/β-Cu<sub>2</sub>ZnSiS<sub>4</sub> meet several criteria for promising nonlinear optical
materials for use in the infrared (IR) region. Both are air-stable,
crystallize in noncentrosymmetric space groups, and possess high thermal
stabilities. Cu<sub>2</sub>CdSnS<sub>4</sub> and α/β-Cu<sub>2</sub>ZnSiS<sub>4</sub> display wide ranges of optical transparency,
1.4–25 and 0.7–25 μm, respectively, and have relatively
large second-order nonlinearity as well as phase matchability for
wide regions in the IR. The laser-damage threshold (LDT) for Cu<sub>2</sub>CdSnS<sub>4</sub> is 0.2 GW/cm<sup>2</sup>, whereas α/β-Cu<sub>2</sub>ZnSiS<sub>4</sub> has a LDT of 2.0 GW/cm<sup>2</sup> for picosecond
near-IR excitation. Both compounds also exhibit efficient third-order
nonlinearity. Electronic structure calculations provide insight into
the variation in properties