Bio inspired synthesis of silver nanoparticles and its applications to spin – orbit interactions of light

Spin–orbit interaction of light serves as an important property of light, which deals with the study of polarization and phase modulations in the light beam. These studies are essential and principal characeristics of light beam that have been used for most of the nanophotonics applications. Silver nanoparticles (Ag NPs) prepared via biosynthesis are used for one of such nanophotonics application in scattering via studying the light scattered through these nanoparticles. The silver nanoparticles Ag NPs were synthesized using green method, where reduction of silver ions to silver nanoparticles happen during the reaction of aqueous solution of Ag NO3 with the biomolecules present in fresh leaf extract of Coleus amboinicus plant. The nanoparticles were characterized using UV-visible (UV–vis) spectroscopy, Transmission electron microscopy (TEM) and Fourier Transform Infrared (FTIR) spectroscopy. TEM analysis shows the wide size distribution of spherical shape nanoparticles with 80 nm average size. The study of polarization and phase changes in the scattered light field has been carried out using Stokes polarimetry in forward direction scattering. Under the preliminary measurements of Polarimetry, the modification in the polarization components was studied by demonstrating changes in the Stokes S2, S3 parameters, polarization orientation (ψ) and ellipticity angle (χ) using transverse magnetic (TM) polarized Gaussian light beam.