Picosecond nonlinear optical studies of gold nanoparticles synthesised using coriander leaves (Coriandrum sativum)

Abstract

The results are presented from the experimental picosecond nonlinear optical (NLO) studies of gold nanoparticles synthesised using coriander leaf (Coriandrum sativum) extract. Nanoparticles with an average size of ∼30 nm (distribution of 5–70 nm) were synthesised according to the procedure reported by Narayanan et al. [Mater. Lett. 2008, 62, 4588–4591]. NLO studies were carried out using the Z-scan technique using 2 ps pulses near 800 nm. Open-aperture data suggested saturation absorption as the nonlinear absorption mechanism, whereas closed-aperture data suggested a positive nonlinearity. The magnitude of third-order nonlinearity was estimated to be (3.3 ± 0.6) × 10⁻¹³ esu. A solvent contribution to the nonlinearity was also identified and estimated. A comparison is attempted with some recently reported NLO studies of similar gold nanostructures.

Keywords:

• gold nanoparticle
• nonlinear absorption
• coriander leaves
• Z-scan
• picosecond

Acknowledgements

S.V. Rao acknowledges the encouragement of Prof. Surya P. Tewari, ACRHEM and Prof. D. Narayana Rao, School of Physics. We also acknowledge the assistance of Dr Sathyavathi, School of Physics during synthesis. S.V. Rao acknowledges financial support from CSIR, India.