N.K. Siji Narendran

Third-order nonlinear optical investigations of meso-tetrakis(2,3,5,6-tetrafluoro-N,N-dimethyl-4-anilinyl)porphyrin and its metal complexes.

We report here the experimental investigation on third-order nonlinear optical parameters of 5,10,15,20-tetrakis(2,3,5,6-tetrafluoro-N,N-dimethyl-4-anilinyl)porphyrin and its various metal complexes, using Z-scan technique at 532 nm. The third-order nonlinear optical susceptibilities (χ(3)) were of the order 10(-12) esu and are compared through degenerate four wave mixing (DFWM). The operating mechanism is reverse saturable absorption (RSA) as the effective excited-state absorption cross-section was found higher than ground state absorption cross-section as well as the magnitude of nonlinear absorption coefficient was found decreasing with on-axis input intensity. The compounds found to exhibit good optical limiting at 532 nm, 7 ns excitation steering applications in laser safety.

χ(3) measurements of axial ligand modified high valent tin(IV) porphyrins using degenarete four wave mixing at 532nm

Porphyrins and metalloporphyrins are unique class of molecules for Nonlinear Optical applications because of their unique structure of altering the central metal atom, large extended π-system, high thermal stability, tunable shape, symmetry and synthetic versatility Here, we report χ(3) Measurements of a simple phenyl porphyrins and its highvalent tin(IV) porphyrins with Bromination characterized by UV-Visible spectroscopic method. In this study, we employed the Degenerate Four Wave Mixing technique using forward Boxcar geometry with an Nd:YAG nano second pulsed laser as source and it was found that the tin(IV) porphyrin with Bromination exhibits good χ(3) value and figure of merit.

Synthesis and third order optical investigations of nitrophenyl porphyrins

The third-order nonlinear optical studies of Nitrophenyl Porphyrins using degenerate fourwave mixing has been done. Samples were prepared using standard methods. Study shows that the compounds have high χ3 Values suitable for photonic applications.

Third Order Nonlinear Optical Studies of ZnS Nanostructures Synthesized by Laser Ablation Technique

We report the nonlinear optical (NLO) studies of ZnS nanostructures (NS) in polyvinyl pyrrolidone/dimethyl formamide (PVP/DMF) synthesized by laser ablation technique. We used a frequency doubled Q-switched Nd:YAG laser operating at 532 nm with a repetition rate of 10 Hz, 7 ns pulse width for ablation. The obtained nanoparticles showed a maximum absorption peak at 270.5 nm and were further chararacterized by Transmission Electron Microscope (TEM), X ray diffractometer (XRD), and Scanning Electron Microscope (SEM) from which the formation of NS was confirmed. The third order nonlinear optical susceptibility (χ(3)) of nanocomposite was measured using the single beam Z-scan technique. The mechanism behind the nonlinear absorption was confirmed to be two photon absorption (2PA) as the open aperture Z-scan curves of ZnS NS were fitted well to the theoretical model for 2PA. Also, the unvarying values of the nonlinear absorption coefficient (βeff) with different on-axis input intensities endorse 2PA as the principal absorption mechanism. The χ(3) value measured was 4.7 × 10−12 esu which ensures its potential usefulness in photonic applications exploiting optical limiting property.

Effect of Electric Field on Nonlinear Optical Properties of Hydrazone Doped PMMA Films

We report the effect of electric field on third order nonlinear optical properties of Hydrazone (Hz) doped Polymethyl methacrylate (PMMA) films. The films were prepared by solution casting method. Poling of films was done by corona discharge. Single beam Z-scan technique with 7ns Nd: YAG laser pulses at 532nm were employed for the measurements. Third order susceptibility of films was measured with an emphasis on the applied electric field. We also demonstrated the second harmonic generation in the corona poled films.