We have studied the third-order nonlinear optical properties of niobium-rich lithium niobite (LN) thin films prepared by magnetron sputtering at room temperature and annealed at 700 °C in high-purity oxygen. The third-order nonlinear optical properties of the LN films were investigated by the Z-scan method at a wavelength 1064 nm and a pulse duration 25 ps. The Z-scan results show that the LN films exhibit reverse saturation absorption and self-focusing behaviors. The third-order nonlinear refractive index γ and the absorption coefficient β were determined around 10⁻¹¹ cm²/W and 10⁻⁷ cm/W, respectively. The γ is four orders of magnitude larger than that in the LN single crystals measured at the pulse duration 25 ps but the wavelength 532 nm, while two orders of magnitude smaller than that in the LN films measured at the wavelength of 532 nm and 800 nm, respectively. The nonlinear absorption in our LN films also significantly decreased compared with that in the reported LN films. Our results show that the optical nonlinearity of LN films can be significantly affected by the atom composition and incident wavelength, and will be of significance for LN-based integrated on-chip photonic devices.

我们研究了在室温下通过磁控溅射制备的富铌铌铌酸锂（LN）薄膜的三阶非线性光学性质，并在高纯度氧气中于700°C退火。通过Z扫描法在波长1064nm和脉冲持续时间25ps下研究了LN膜的三阶非线性光学性质。Z扫描结果表明，LN膜表现出反向饱和吸收和自聚焦行为。在10 ^-11  cm ² / W和10 ^-7附近确定三阶非线性折射率γ和吸收系数β cm / W。γ比在脉冲持续时间25 ps但波长532 nm下测量的LN单晶大四个数量级，而比在532 nm和800 nm波长下测量的LN薄膜小两个数量级。 ， 分别。与已报道的LN膜相比，我们的LN膜的非线性吸收也显着降低。我们的结果表明，LN薄膜的光学非线性会受到原子组成和入射波长的显着影响，这对于基于LN的集成芯片上光子器件将具有重要意义。