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The third order nonlinear optical properties i.e. nonlinear refraction (n 2), absorption coefficient (β) and third order susceptibility χ(3) of glycine zinc sulphate pentahydrate (GZS) semi-organic single crystal was investigated under the excitation of Q-switched Nd-YAG laser pulsed radiations (λ = 532 nm & 1064 nm) by familiar Z-scan method. The values of nonlinear refraction (n 2), at 532 nm were 1.19 × 10−5 (cm2/GW), 2.09 × 10−5 (cm2/GW), 2.27 × 10−5 (cm2/GW), 2.48 × 10−5 (cm2/GW), and 2.55 × 10−5 (cm2/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 4.31 × 10−5 (cm2/GW), 4.69 × 10−5 (cm2/GW), 5.41 × 10−5 (cm2/GW) and 6.39 × 10−5 (cm2/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of nonlinear absorption coefficient (β) at 532 nm were −1.45 (cm/GW), −0.79 (cm/GW), −0.5 (cm/GW), 0.12 (cm/GW) and 0.64 (cm/GW) at incident optical beam intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 0.62 (cm/GW), 0.74 (cm/GW), 0.77 (cm/GW) and 0.81 (cm/GW) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. The values of third order susceptibilities χ(3) at 532 nm were 0.83 × 10−12 (esu), 1.32 × 10−12 (esu), 1.42 × 10−12 (esu), 1.55 × 10−12 (esu) and 1.56 × 10−12 (esu) at intensities of 0.76 (GW/cm2), 1.13 (GW/cm2), 1.17 (GW/cm2), 1.63 (GW/cm2) and 1.88 (GW/cm2) respectively while that of values at 1064 nm were 2.71 × 10−12 (esu), 2.96 × 10−12 (esu), 3.4 × 10−12 (esu) and 4.02 × 10−12 (esu) at incident optical beam intensities of 1.20 (GW/cm2), 1.25 (GW/cm2), 1.32 (GW/cm2) and 1.38 (GW/cm2) respectively. It was seen that the sample showing saturable absorber to reverse saturable absorber at 532 nm wavelength at incident optical beam peak intensity (I 0) of 1.53 GW/cm2. Thus the crystal could be a potential candidate of optical switching application. It was also seen that the material possess positive nonlinearity. It was also found that the values of nonlinear absorption coefficient (β) and nonlinear refraction (n 2) increase with increase of excitation intensity irrespective of excitation wavelengths. [ABSTRACT FROM AUTHOR]

Third order nonlinear optical properties of organic crystal L-threoninium P-toluenesulfonate monohydrate was investigated by 'Z-scan' technique employing two different laser sources under different intensities at 532 nm CW laser and 1064 nm pulsed laser respectively. Nonlinear absorption coefficient (α NL) and nonlinear refraction (n 2) were evaluated at six different intensities using 532 nm CW laser source and with pulsed laser source (λ = 1064 nm) by changing the pulse rate keeping intensity same. It is found that this crystal possesses positive nonlinearity and exhibit saturation absorption. • NLA coefficient (β) and NLR (n 2) of L-threoninium P-toluenesulfonate monohydrate organic single crystal using two laser sources at 532 nm and 1064 nm. • It is found that this crystal possess positive nonlinearity and exhibit saturation absorption. • The nonlinear absorption of this crystal found to be negative. • This crystal may be useful in optical switching application. [ABSTRACT FROM AUTHOR]

The results of electro-optical modulator and third order nonlinearity of an organic single crystal of Imidazolium l -tartrate (IMLT) 〈0 1 0〉 grown by unidirectional growth method of Sankaranarayanan–Ramasamy (SR) are discussed for the first time in literature. The grown IMLT seed crystals were characterized by single crystal XRD and the lattice parameters were confirmed. The UV–Visible transmittance analysis shows that SR method grown IMLT single crystal possesses good transmittance in the entire visible region with a low cut-off wavelength at 240 nm. The mechanical study on the (0 1 0) plane of the IMLT single crystal analyzed by Vickers microhardness tester reveals the moderate hardness of the material. Photoconductivity studies on pure IMLT single crystal enumerated the positive photoconducting nature. Refractive index of the IMLT single crystal was determined by Brewster angle method. Second Harmonic Generation (SHG) efficiency of IMLT is 4.3 times greater than the standard Potassium Dihydrogen Phosphate (KDP) crystal. Nonlinear refractive index ( n 2 ), nonlinear absorption coefficient ( β ) and third-order nonlinear optical susceptibility χ (3) were evaluated using Z-scan method. The half wave voltage and electro-optical coefficient of IMLT crystal were determined using polarimetric technique. The electro-optical coefficient ( r 12 ) of IMLT is found to be greater than that of KDP crystal which represents the suitability of IMLT crystal to design the electro-optical modulator with low half wave voltage for nonlinear optical applications. [ABSTRACT FROM AUTHOR]

The preparation and NLO characterization of photosensitive polyesters containing azoaromatic residues in the molecular backbone, functionalized with orthohydroxy chromophores is presented. Samples were studied for its UV–vis absorption, FT-IR and intensity dependent nonlinear absorption properties. Nonlinear characterization was carried out with z-scan using frequency doubled, Q-switched Nd:YAG laser operating at 532 nm. The closed aperture z-scan spectra reveal the self defocusing effects of the samples with negative nonlinearity coefficient ( n 2 ) showing values as high as −1.28 × 10 −10 (esu) for certain samples and the corresponding third order susceptibility coefficient of the order of 29.9 × 10 −12 (esu). Degenerate four wave mixing technique was employed to substantiate the findings. The numerical fits show that the molecules exhibit reverse saturable absorption. A study of beam fluence dependence of nonlinear absorption coefficient ( β eff ) has been presented. All phenomena indicate that molecules are reverse saturable absorbers whose optical limiting property gets enhanced with increasing conjugation length. [ABSTRACT FROM AUTHOR]

Synthesis of hydrazine hydrate assisted manganese doped zinc selenides by hydrothermal technique led to the formation of good quality nanospheres which are controlled by Ostwald ripening process. Structural studies using XRD showed the incorporation of manganese in zinc selenide matrix with their crystallite sizes ranging between 10 and 15 nm, which corroborate with the TEM measurements. Dominant emission (517 nm) corresponds to the near band edge emission as observed from photoluminescence spectra. Presence of impurities and defects were identified from various other emissions as well as from the bandgap variation obtained from reflectance spectra. The third order nonlinearity of manganese doped zinc selenide nanoparticles were calculated by the standard Z-scan technique using 532 nm CW DPSS and nanopulsed Nd:YAG laser. Mn doped ZnSe nanoparticles which exhibits near resonant excited state absorption were found to be an ideal candidate to be exploited as optical limiters in protecting optical components from high intense laser pulses. Further, lower onset optical limiting threshold under pulsed laser excitation of manganese doped zinc selenides (2.92 × 1012 Wm−2) compared to pure zinc selenide (4.98 × 1012 Wm−2) confirms that doping of Mn in ZnSe can yield efficient energy absorbing optical limiters. Image 1 • Mn2+ doped ZnSe nanoparticles were synthesized by hydrothermal method. • Ostwald ripening process leads to the formation of spherical nanoparticles. • Structural, linear and nonlinear optical properties are studied. • Third order nonlinearity of the synthesized nanoparticles was studied by Z-scan technique using both CW and pulsed lasers. • Optical limiting studies reveal that the synthesized nanoparticles can be exploited as good optical limiters. [ABSTRACT FROM AUTHOR]

Here, we report the role of different stabilizers (Eu 2 O 3 , EuF 3 and KSCN) in stabilizing gold nanoparticles (AuNPs) embedded in Bismuth-Borosilicate glasses. The prepared nanocomposites are characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), UV–Visible transmission spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), ellipsometery and Z-scan. From FESEM, it has been observed that the morphology of AuNPs is highly dependent on the type of stabilizer. Also HRTEM confirms the covering of AuNPs by stabilizer that prevents the coagulation of NPs. The localized surface plasmon resonance related transmission dip is observed around 585 nm for glass containing Eu 2 O 3 as a stabilizer. The linear and nonlinear refractive index of the prepared glasses is obtained from ellipsometery and Z-scan measurements, respectively. All the Z-scan measurements have been carried out at different input peak intensities varying from 1.9 to 14.38 GW/cm2. Nonlinear optical studies with open aperture Z-Scan shows the switching between saturable absorption and two photon absorption as the laser intensity is increased. The existence of third order nonlinearity has been detected using closed aperture Z-scan in the prepared glasses. • Gold nanoparticles embedded in Bismuth borosilicate glasses stabilized by Eu 2 O 3 , EuF 3 and KSCN. • Up to Third order non-linearity is observed in closed aperture Z-scan. • High refractive index in UV-VIS-NIR observed in ellipsometery measurements. • Prepared glasses having potential applicant for long range surface plasmon resonance sensors. [ABSTRACT FROM AUTHOR]