We report the influence of reduction time on structural, linear and nonlinear optical properties of reduced graphene oxide (rGO) thin films synthesized by spin coating method. We observed that the structural, linear and nonlinear optical properties can be tuned with reduction time in GO is due to the increased structural ordering because of the restoration of sp2 carbon atoms with the time of reduction. The nonlinear absorption studies by open aperture Z-scan technique exhibited a saturable absorption. The nonlinear refraction studies showed the self de focusing nature of rGO by closed aperture Z scan technique. The nonlinear absorption coefficient and saturation intensity varies with the time for reduction of GO which is attributed to the depletion of valence band and the conduction band filling effect. Our results emphasize duration for reduction of GO dependent optical nonlinearity of rGO thin films to a great extent and explore its applications Q switched mode locking laser systems for generating ultra short laser pulses and in optical sensors. The rGO coated films were characterized by X-Ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–Vis absorption spectroscopy (UV–Vis), Photoluminescence (PL) and Scanning electron microscope (SEM) measurements. © 2017 Elsevier B.V.

Vinitha G

Physics

School of Advanced Sciences

Chennai Campus

Sreeja V.G

Reshmi R

Anila E.I

Jayaraj M.K.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Optical Materials

Metal-semi organic NLO single crystal of Cadmium (II) dibromide L - Proline monohydrate (CBLPM) has been synthesized and the crystal was grown from solution by room temperature slow evaporation method. The crystal structure and cell parameters were refined by Rietveld refinement technique and confirmed that the metal-semi organic samples are in the orthorhombic system with space group P212121. The crystal structure of CBLPM is stabilized by intermolecular N–H…O, N–H….Br, O–H….O and O–H….Br hydrogen bonds. The water molecules serve as donors for the weak O–H⋯O and O–H⋯Br hydrogen bonds which link adjacent chains forming a three-dimensional structure. A Hirshfeld surface analysis suggests that the most significant contribution to the crystal packing is by H⋯Br contacts (26.2%). The complete vibrational features and electronic absorption spectra of the title compound were analyzed by FT-IR, FT-Raman and UV–visible spectra combined with density functional theory and time-dependent density functional computations. The second-order hyperpolarizability value of the molecule was also calculated at density functional theory method. The third-order nonlinear optical properties of the crystal were studied by Z-scan techniques using CW laser with wavelength 532 nm. The open aperture result exhibits the saturation absorption, which indicates that this material has potential candidate for optical limiting applications. © 2019 Elsevier B.V.

Journal of Molecular Structure

Synthesis, physicochemical properties and third-order optical nonlinearities of cadmium (II) dibromide l - Proline monohydrate for optical limiting application

We present the structural and third order nonlinear optical properties of Sr2+-doped ZnO nanostructures synthesized by chemical precipitation technique. The prepared nanoparticles are systematically investigated by UV–vis absorption, X-ray diffraction (XRD), Photoluminescence spectroscopy and Field emission scanning electronic microscopy (FESEM), respectively. UV–vis absorption spectra show that the particles have a higher absorption in UV region and possess a large optical transparency in visible region. XRD patterns show that all the prepared nanoparticles are well crystallized with hexagonal wurtzite structure. The incorporation of Sr in ZnO was also confirmed by fluorescence quenching. FESEM images showed the formation of nanostructures with sheet-like structure. Third-order nonlinear optical properties of the nanostructures have been studied by Z-scan technique using diode pumped continuous wave (cw) laser system at a wavelength of 532 nm. Experimental results reveal that the materials exhibit saturable absorption (SA) and self-defocusing nature. © 2018 Elsevier Ltd

Optics & Laser Technology

Effect of Sr2+ doping on the linear and nonlinear optical properties of ZnO nanostructures

We report the effect of rGO on structural, electrical, spectral and nonlinear optical properties of reduced graphene oxide-polyaniline (rGO-PANI) nanocomposites. The rGO-PANI composites with different concentration of rGO were synthesized through an in situ polymerization method. The structural and optical studies of the composite powders show that the template effect of rGO provides a well ordered structure of PANI with better crystallinity. This may be due to the strong electrostatic, p–p, and hydrogen bond interactions between PANI and rGO materials. The conductivity of the composite material increases with respect to pure PANI up to a particular limit, and then decreases. It is mainly due to the disordered conjugated structure of PANI. The nonlinear optical properties of rGO–PANI composites are evaluated by Z-scan technique using a continuous wave Nd:YAG laser at a wavelength of 532 nm. Two photon absorption is the main mechanism behind the self defocusing nature of rGO - PANI composites. The saturable absorption behavior of the material is due to the depletion of valence band and the band filling effect of sp2 carbon domains. The nonlinear absorption coefficient and refractive index of the samples are also estimated and the results show that rGO-PANI composite material is a promising candidate for the applications in optical switching, optical sensors and in ultrafast photonics. © 2019 Elsevier Ltd. All rights reserved.

Materials Today: Proceedings

Structural, Spectral, Electrical and Nonlinear Optical Characterizations of rGO-PANI Composites

Third-order nonlinearity of monoclinic and orthorhombic phase of CuNb2O6 is studied in low power regime of 532 nm by Z-scan technique. In open aperture, monoclinic CuNb2O6 possess stronger saturable absorption due to the distorted structure arising from unequal arrangement of copper atoms. Closed aperture exposes the self-defocusing nature and orthorhombic phase exhibits stronger nonlinear refraction. Variation in third-order NLO coefficient due to change in phase and morphology of CuNb2O6 confirms the influence of sintering temperature and time. Microrod monoclinic CuNb2O6 possess maximum nonlinear absorption coefficient (6.47 × 10−3 cm/W) and pure orthorhombic CuNb2O6 attains maximum nonlinear refractive index (5.13 × 10−8 cm2/W) along with higher third-order nonlinear optical susceptibility (1.91 × 10−6 esu). Higher thermal nonlinearity resulted in stronger optical limiting action with pure orthorhombic CuNb2O6 (5.16 mW, 1.26 mW) compared to other phases. For understanding the material suitability for laser safety device, nonlinearity and limiting action of CuNb2O6 thin films were demonstrated. Earlier formation of monoclinic phase with morphology change (700 °C) and transition of monoclinic rich mixed orthorhombic phase to pure orthorhombic phase (900 °C) with increase in sintering time (3–12 h) was confirmed by XRD, FTIR and SEM analysis. Thus orthorhombic CuNb2O6 material with stronger self-defocusing and optical limiting action makes it more preference than monoclinic CuNb2O6 for third-order NLO applications. © 2018 Elsevier Ltd

Third order nonlinear optical properties of monoclinic and orthorhombic CuNb2O6 under CW laser illumination

Effect of thickness on nonlinear absorption properties of graphite oxide thin films

ACS Nano

Rearrangement of π-Electron Network and Switching of Edge-Localized π State in Reduced Graphene Oxide

Optik

Third order nonlinear optical properties of potassium dichromate single crystals by Z-scan technique

Nature Photonics

Nanotube and graphene saturable absorbers for fibre lasers

Optics Express

Transient thermal effect, nonlinear refraction and nonlinear absorption properties of graphene oxide sheets in dispersion

Effect of reduction time on third order optical nonlinearity of reduced graphene oxide

Journal	Data powered by TypesetOptical Materials
Publisher	Data powered by TypesetElsevier BV
ISSN	0925-3467
Open Access	No