Abstract The present study focuses on determination of spectral and third-order nonlinear optical (NLO) properties of a natural pigment chlorophyll-a have been extracted from the leaves of coriandrum sativum (coriander). The extraction was carried out by a column chromatography technique, is a sensitive method for isolating the natural pigment chlorophyll-a from coriandrum sativum. The spectral characteristics of the natural pigment were examined by UV–Vis absorption, emission and FT-IR spectra, respectively. The concentration of chlorophyll-a in coriandrum sativum was measured to be 48.6 mg/g using UV–Vis absorption spectra. A peak tailed by a valley curve was noted in closed aperture Z─scan technique due to self-defocusing and open aperture Z─scan curve signifies the reverse saturable absorption (RSA) behavior. The existence of RSA in chlorophyll-a was ensured by ground and excited state absorption cross-section. The real and imaginary parts of the third-order NLO susceptibility of chlorophyll-a were found to be the order of 10─15 m2/V2. The natural pigment exhibits a low optical limiting (OL) threshold of 4.22 × 102 W/cm2 under continuous wave laser regime. The experimental results revealed that the natural pigment chlorophyll-a extracted from the leaves of coriandrum sativum is a potential material for photonics and optoelectronics applications.

中文翻译：

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芫荽提取天然色素的光谱和三阶非线性光学特性

摘要 本研究的重点是确定从香菜（香菜）叶子中提取的天然色素叶绿素 a 的光谱和三阶非线性光学 (NLO) 特性。萃取采用柱层析技术，是一种从香菜中分离天然色素叶绿素-a 的灵敏方法。天然色素的光谱特性分别通过 UV-Vis 吸收、发射和 FT-IR 光谱进行检测。使用 UV-Vis 吸收光谱测量香菜中叶绿素 a 的浓度为 48.6 mg/g。由于自散焦，在闭孔 Z 扫描技术中注意到一个由谷曲线拖尾的峰，而开孔 Z 扫描曲线表示反向饱和吸收 (RSA) 行为。叶绿素a中RSA的存在是由基态和激发态吸收截面确定的。发现叶绿素-a 的三级 NLO 磁化率的实部和虚部为 10─15 m2/V2 的数量级。天然色素在连续波激光状态下表现出 4.22 × 102 W/cm2 的低光学限制 (OL) 阈值。实验结果表明，从香菜叶子中提取的天然色素叶绿素-a 是一种潜在的光子学和光电子学应用材料。22 × 102 W/cm2 在连续波激光状态下。实验结果表明，从香菜叶子中提取的天然色素叶绿素-a 是一种潜在的光子学和光电子学应用材料。22 × 102 W/cm2 在连续波激光状态下。实验结果表明，从香菜叶子中提取的天然色素叶绿素-a 是一种潜在的光子学和光电子学应用材料。