Green Synthesis of Silver Nanoparticles Using Justicia adhatoda Leaf Extract: Characterization and Nonlinear Optical Applications

This study reports the synthesis of silver nanoparticles (AgNPs) using leaf extract of Justicia adhatoda . This green and eco‐friendly method produces highly stable AgNPs, which are characterized using various techniques, including UV–visible absorbance, FT‐IR, XRD, FESEM, and TEM. A strong surface plasmon resonance (SPR) is observed at a wavelength of 411 nm. The functional groups present in the AgNPs are identified using FT‐IR, revealing a peak at 456 cm −1 corresponding to Ag + bond vibration. The crystalline properties of AgNPs are examined via XRD, with an average crystal size measured at 23.33 nm. Moreover, FESEM and TEM studies revealed that the nanoparticles possess a spherical shape. The Z‐scan technique is employed at a wavelength of 405 nm to investigate the third‐order nonlinear optical (NLO) responses of AgNPs. The nonlinear refractive index ( n 2 ) and nonlinear absorption coefficient ( β ) are attributed to self‐defocusing and reverse saturable absorption (RSA) processes. A significant third‐order NLO susceptibility is measured, estimated to be in the order of 10 −7 esu. Overall, the experimental results clearly indicate that the green synthesis of AgNPs using the leaf extract of Justicia adhatoda represents a promising material for NLO applications.