In this work, we extract the natural dye ingredient found in Indigofera Tinctoria leaves, and investigate its nonlinear optical absorption by employing the Z-scan technique. The dye is extracted from Indigo powder which is commercially available for hair coloring applications. The powder, which is made by grinding Indigofera Tinctoria leaves into fine particles, is mixed with water, sonicated, centrifuged and filtered to give an optically clear extract. Linear absorption of the extract is measured in the visible spectral region using a spectrophotometer. Nonlinear absorption in the green spectral region is measured using 5 ns (5 × 10⁻⁹ s), 532 nm laser pulses obtained from a frequency-doubled Nd:YAG laser. The Indigofera Tinctoria dye is found to show excellent nonlinear absorption, which arises from strong reverse saturable absorption occurring in the sample at this wavelength. The third order nonlinear absorption coefficient, which is obtained by numerically fitting the Z-scan data to the nonlinear transmission equation, has a high value in the order of 10⁻¹⁰ m/W. This high nonlinear absorption, which is in the same range as that of materials such as graphene oxide, leads to an excellent optical limiting behavior, making Indigofera Tinctoria a potential candidate for fabricating optical limiter devices for eye and sensor protection.

在这项工作中，我们提取了在靛蓝靛蓝叶片中发现的天然染料成分，并通过Z扫描技术研究了其非线性光学吸收。染料是从靛蓝粉末中提取的，靛蓝粉末可从市场上买到，用于染发。通过将印度洋靛蓝（Indigofera Tinctoria）叶片研磨成细颗粒而制成的粉末，与水混合，超声处理，离心分离并过滤，得到光学透明的提取物。使用分光光度计在可见光谱区域中测量提取物的线性吸收。使用 倍频Nd：YAG激光获得的5 ns（5×10 ^-9 s）532 nm激光脉冲测量绿色光谱区域中的非线性吸收。该木蓝发现该染料显示出出色的非线性吸收，这是由于在该波长下样品中发生的强烈的反向饱和吸收所引起的。通过将Z扫描数据数值拟合到非线性传输方程而获得的三阶非线性吸收系数具有10 ^-10  m / W量级的高值。这种高的非线性吸收与诸如氧化石墨烯的材料处于相同的范围内，从而导致了出色的光学限制行为，使得Indigofera Tinctoria成为制造用于保护眼睛和传感器的光学限制器的潜在候选者。