T.C. Sabari Girisun

Bio: T.C. Sabari Girisun is an academic researcher from Bharathidasan University. The author has contributed to research in topics: Materials science & Z-scan technique. The author has an hindex of 16, co-authored 74 publications receiving 904 citations. Previous affiliations of T.C. Sabari Girisun include Bishop Heber College.

Linear and nonlinear optical properties of tris thiourea zinc sulphate single crystals

Abstract: Optical absorption of tris thiourea zinc sulphate (ZTS) single crystals has been measured and its direct band gap was found to be 3.6 eV. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearties of ZTS have been investigated by Z-scan technique with He-Ne laser at 632.8 nm. The nonlinear refractive index, absorption coefficient and third order susceptibility is found to be in the order of –5.36 ± 0.26 × 10–12 cm2/W, 4.24 ± 0.21 × 10–4 cm/W, 3.5 ± 0.17 × 10–4 esu respectively. Thus optical characterization of ZTS reveals the various industrial application oriented properties of the material. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Improved third-order optical nonlinearity and optical limiting behaviour of (nanospindle and nanosphere) zinc ferrite decorated reduced graphene oxide under continuous and ultrafast laser excitation

Abstract: Nanohybrids consisting of uniform nanospheres and nanospindles of zinc ferrite attached to reduced graphene oxide were prepared by hydrothermal reaction. Zinc ferrite decorated reduced graphene oxide exhibited enhanced nonlinear absorption, refraction and optical limiting (OL) action under continuous wave (532 nm, 50 mW) and ultrafast (800 nm, 150 fs) excitation. The enhancement can possibly be attributed to the synergistic effect stemming from the observed reverse saturable absorption and self-defocusing in the material. The role of defects in improving the nonlinear optical (NLO) performance of ZnFe2O4–rGO was explained with the aid of Raman spectroscopy and ground state absorption studies. Using fs and cw excitation, the estimated nonlinear absorption coefficient [γ3PA(fs) = 4.0 × 10−12 m W−1, β(cw) = 6.5 × 10−5 m W−1], nonlinear refractive index [n2(fs) = 4.2 × 10−18 m2 W−1, n2(cw) = 4.7 × 10−12 m2 W−1] and third order nonlinear optical (NLO) susceptibility [χ (3) (fs) = 1.9 × 10−15 esu, χ (3) (cw) = 4.2 × 10−6 esu] of nanospindle ZnFe2O4–rGO were found to be higher than those of its other counter parts. The estimated NLO parameters were found to be higher than those of other known OL materials such as functionalized hydrogen exfoliated graphene, CdO. Thus zinc ferrite decorated rGO nanostructures with proficient NLO coefficients have potential scope for utilizing them as smart materials for OL applications.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

Abstract: The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the functi...

Ultralarge All-Inorganic Perovskite Bulk Single Crystal for High-Performance Visible–Infrared Dual-Modal Photodetectors

Abstract: Visible-infrared dual-modal light harvesting is crucial for various optoelectronic devices, particularly for solar cells and photodetectors. For the first time, this study reports on large 25 cm3-volume all-inorganic perovskite CsPbBr3 single crystal (SC) with an emphasis on the observed visible-infrared dual-modal light harvesting and sensing as demonstrated by the high-performance visible-infrared dual-modal photodetectors. First, ultralarge 25 cm3-volume CsPbBr3 SC ingots with trapping state density as low as of 1 × 109 cm−3 have been achieved by a modified Bridgman growth method. The volume reported here is the largest CsPbX3 (X = Cl, Br, I) all-inorganic perovskite system up to now, and the SC can be facilely cut into SC wafers with a diameter of 25 mm for various optoelectronic devices. Furthermore, these CsPbBr3 SCs exhibit a visible absorbance coefficient, a near-infrared (IR) two-phonon absorption coefficient, a carrier diffusion length, and a mobility as high as of 105 cm−1, 3.7 cm per Goeppert-Mayer (GM), 10 µm and 2000 cm2 V−1 s−1, respectively. These merits match well to the requirements of high-performance Vis-IR dual-modal light harvesting optoelectronic devices, which has been demonstrated by the CsPbBr3 SC photodetectors operated under the irradiation of both visible and IR light sources with light on/off ratio higher than 103. These results demonstrate the CsPbBr3 SCs with high visible-infrared dual-modal light harvesting capability and excellent electrical transporting properties have a huge potential in various optoelectronic devices, such as solar cells, photodetectors, and lasers.

Investigation of synthesis, crystal structure and third-order NLO properties of a new stilbazolium derivative crystal: a promising material for nonlinear optical devices

Abstract: A new organic stilbazolium derivative crystal 2-[2-(3-hydroxy-4-methoxy-phenyl)-vinyl]-1-methyl-pyridinium naphthalene-2-sulfonate dehydrate (C25H23NO5S·2H2O) (VSNS) was synthesized successfully. Single crystals were grown in a mixed solvent of methanol–acetonitrile (1 : 1) using a slow evaporation method at room temperature. Solubility of the synthesized VSNS material was experimentally determined for various temperatures using a methanol–acetonitrile mixed solvent. A single crystal X-ray diffraction study confirmed the crystal structure and morphology of VSNS. The crystalline nature of the title material was analyzed by powder X-ray diffraction analysis, and the presence of expected functional groups and the molecular structure of VSNS was identified by FT-IR and 1H NMR spectroscopic studies. Optical absorption was recorded using UV-Vis-NIR spectral analysis, and linear optical constants such as the absorption coefficient, band gap, extinction coefficient, refractive index and reflectance were calculated. The luminescence property of the crystal grown showed green emission radiation. The thermal stability of the crystal was analyzed by TG–DTA studies, and the hardness, Meyer index, yield strength, and elastic stiffness constant were estimated using a Vickers microhardness tester. Layer growth pattern was observed in chemical etching studies using a Carl Zeiss optical microscope at 50× magnification. Laser damage threshold energy was measured using an Nd:YAG laser (1064 nm). Variation of the dielectric response of the grown crystal was studied at room temperature. The third-order nonlinear optical property of VSNS was investigated in detail using a Z-scan technique with He–Ne laser at 632.8 nm. The second-order molecular hyperpolarizability γ of the crystal grown was 7.986 × 10−34 esu. This encouraging result of the Z-scan studies suggests that the VSNS crystal is a candidate material for photonics devices, optical switches, and optical power limiting applications.