Natural Pigments of Aloe vera: A Third-Order NLO Material

• Published in: Brazilian journal of physics 2022-02, Vol.52 (1), Article 24
• Main Author: Jeyaram, S.
• Format: Article
• Language: English
• Subjects: Absorption cross sections; Absorptivity; Aloe; Condensed Matter; Constraining; Continuous wave lasers; Defocusing; Nonlinear optics; Physics; Physics and Astronomy; Pigments; Refraction; Refractivity
• ISSN: 0103-9733; 1678-4448
• DOI: 10.1007/s13538-021-01031-1

This paper reports the extraction of natural pigments from aloe vera plant, their characterization, and applications to optical limiting. The extracted natural pigment was characterized by UV − Vis absorption, FT-IR, and X-ray diffraction (XRD) techniques, respectively. The morphology of the aloe vera powder was examined by scanning electron microscope (SEM). Z-scan method has been used to perform the experiments with a 635-nm continuous wave laser, and it divulges that the sample possesses a negative nonlinear index of refraction of − 2.31 × 10 −12 m 2 /W and positive nonlinear absorption coefficient of 2.42 × 10 −5  m/W. The negative or self-defocusing nonlinear index of refraction ( n 2 ) of the natural pigment is due to thermal origin, and positive nonlinear coefficient of absorption ( β ) of the sample is owing to reverse saturable absorption (RSA). The RSA behavior of the natural pigment has been confirmed by measured absorption cross-section of the ground and excited states. Further, the sample shows a low optical limiting threshold of 0.24 kW/cm 2 . The experimental results prove the possibility of utilizing this natural pigment for future applications in nonlinear optics.