Magnitude Of Nonlinear Refractive Index Research Articles

Single Beam Measurements of a Sony SVGA Liquid Crystal Spatial light modulator

In this work, non-linear optical properties of a Sony SVGA liquid crystal spatial light modulator sample are estimated by utilizing a single beam Z-scan technique with He-Ne laser at 632.8 nm. It was found that the magnitude of non-linear refractive index (NLR) is (0.694×10-7 cm2/mW) with a positive signal, demonstrates a self-focusing phenomenon, while the magnitude of non-linear absorption (NLA) for this sample is (0.0101×10-1 cm/mW), the pure magnitude of the NLR is (0.138×10-5 cm2/mW). These results are compared with past investigations in various liquid crystals types. The obtained results showed that the sample have a high ability of originating optical limiters, switches, and modulation gadgets.

Study of Third-order Nonlinear Optical Properties of Basic Violet 3 Dye in Polar Protic and Aprotic Solvents.

The present work aims to study of third-order nonlinear optical (TONLO) behavior of basic violet 3 dye dissolved in polar protic and aprotic solvents, namely, ethanol, 1-propanol, acetone and dimethyl sulfonate (DMSO), respectively. The polarity of the solvent used to have a substantial impact on the linear and TONLO properties of the dye sample. The dye exhibits self-defocusing nonlinearity due to thermally induced nonlinear refractive index and nonlinear absorption coefficient reveals the character of both saturable and reverse saturable absorption (RSA). The order of magnitude of nonlinear refractive index (n2) and nonlinear coefficient of absorption (β) of dye sample was determined to be 10-7 cm2/W and 10-3cm/W, respectively. The real and imaginary factors of the TONLO susceptibility of basic violet 3 dye were measured to be the power of 10-5 esu. The obtained results reveal that the dye sample seems to have the potential candidate for use in various photonics and optoelectronics applications.

Crystal growth, optical, spectroscopic studies, PL behaviour and Hirshfield surface analysis of a third-order nonlinear optical Cesium Hydrogen Oxalate Dihydrate (CHOD) single crystal

Single crystal of oxalato-bridged, Cesium-extended frame work, Cesium Hydrogen Oxalate Dihydrate (CHOD), has been synthesized by slow evaporation solution growth technique. Diffraction studies were used to identify the geometry of the atoms present in the primitive cell of the crystal. The title compound has crystallized in triclinic category-bearing space group P-1. Spectroscopic investigation of the compound was done by FTIR and FT-Raman techniques. From UV–Vis studies, optical absorption edge was ascertained as 241 nm. It has excellent optical transmission window throughout the visible region. Energy dispersive X-ray analysis (EDAX) affirms the presence of Cesium in the compound. Fluorescence decay of the molecules present in the excited state for the crystal was studied. Hirshfield surface maps intermolecular contacts present in the crystal and the contributions made by the contacts were assessed by 2D Finger print plots. Z-Scan studies ascertain the magnitude of nonlinear refractive index and nonlinear refraction.

Z-scan studies on organic crystal (E)-1-(2-chlorobenzylidene) cyclododecane-1-one for photonic applications

2-(2-Chloro-benzylidene)-Cyclododecanone, a cyclic ketone has been synthesized by direct aldol condensation reaction and the single crystals were grown in mixed solved (Tetrahydrofuran and ethanol) by slow evaporation method. The linear optical property of the crystal has been studied in the wavelength range 190 nm–1100 nm and optical constants were calculated theoretically. The saturation absorption and self-defocusing effect were observed in Z-scan technique. The magnitude of nonlinear refractive index (10−10 m2/W), nonlinear absorption (10−3 m/W) and third order nonlinear susceptibility (10−4 esu) has been calculated. The optical response time of the crystal is coming around 10−3 s.

Tailoring the nonlinear optical susceptibility χ(3), photoluminescence and optical band gap of nanostructured SnO2 thin films by Zn doping for photonic device applications

We report the influence of Zinc (Zn) doping on the structural, optical, and nonlinear optical properties of tin oxide (SnO2) thin films prepared by chemical spray pyrolysis technique. The photoluminescence studies shows the formation of oxygen vacancy defect states upon Zn incorporation. Nonlinear behavior observed in NBE emission were attributed to variations in the crystallinity of the samples upon Zn incorporation. X-Ray diffraction patterns reveals that all the films are polycrystalline in nature having tetragonal rutile structure. The band gap energy values decreased from 3.71 eV to 3.30 eV with increase in the Zn concentration due to formation of defect states and atomic structural disordering. The surface morphology and average surface roughness of the samples were investigated using Atomic force microscopy which endorses the shift from the crystalline state to the amorphous state. The sign and magnitude of nonlinear refractive index and nonlinear absorption coefficient was found out by Z-scan technique with a continuous wave laser as the excitation source. The third order optical Susceptibility χ(3) has found to be increased from 1.08 × 10−3 esu to 2.20 × 10−3 esu upon Zn incorporation. The Z-scan results reveal that the films exhibit self-defocusing nonlinearity. Enhancement in the optical nonlinearity upon doping enables the applicability of the material in various optoelectronic device applications.

Studies on linear and nonlinear optical properties of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate crystal

4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) terahertz organic material has been synthesized by the knoevenagel condensation method. DSTMS single crystals were grown in methanol by slow-cooling method. The linear optical property of DSTMS crystal has been studied using UV–Vis-NIR spectroscopy in the wavelength range 190–1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10−10 m2/W), nonlinear absorption (10−3 m/W) and third order nonlinear susceptibility (10−4 esu) has been studied using Z-scan technique. Dielectric property of DSTMS crystal has been studied at frequency range 50 Hz–5 MHz. The electronic properties such as valence electron plasma energy, penn gap, fermi energy, electronic polarization, electric susceptibility of the grown crystal has been studied. Photoluminescence spectrum was recorded using xenon lamp in the range of 450–700 nm. Laser optical damage threshold of DSTMS crystal was calculated (3.57 GW/cm2) using pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns. The refractive index of the crystal (1.571) has been measured using Abbe’s Refractometer. The optical limiting behaviour of DSTMS crystal has been studied using Nd-YAG laser. The response time (τ) of optical limiting power for the crystals is 10−11 s.

Effect of electron beam on structural, linear and nonlinear properties of nanostructured Fluorine doped ZnO thin films

Electron beam induced effects on Fluorine doped ZnO thin films (FZO) grown by chemical spray pyrolysis deposition technique were studied. The samples were exposed to 8MeV electron beam at different dose rate ranging from 1kGy to 4kGy. All films exhibit a polycrystalline nature which shows an increase in crystallanity with irradiation dosages. The electron beam irradiation effectively controls the films surface morphology and its linear optical characteristics. Z-Scan technique was employed to evaluate the sign and magnitude of nonlinear refractive index and nonlinear absorption coefficient using a continuous wave laser at 632.8nm as light source. Enhancement in the third order nonlinear optical properties was were noted due to electron beam irradiation. Tailoring the physical and NLO properties by electron beam, the FZO thin films becomes a promising candidate for various optoelectronic applications such as phase change memory devices, optical pulse compression, optical switching and laser pulse narrowing.

Synthesis and femtosecond third order nonlinear optical properties of push-pull trans-A2B-corroles

Six novel push-pull trans-A2B free base corroles (1–6) were synthesized and characterized by various spectroscopic techniques. The charge-transfer ability of these trans-A2B-corroles was reflected from the broadness of the UV–visible absorption spectral bands. Corroles 1 and 2 exhibited absorption at lower wavelengths, higher quantum yield and longer singlet state lifetime as compared to 3–6. The ultrafast nonlinear optical (NLO) properties of these corroles were evaluated in visible range (at 800 nm) using the femtosecond Z-scan technique. The investigated corroles possess negative type of nonlinearity and self-defocusing behavior with the magnitude of nonlinear refractive index (n2) in the range of 0.36–2.84 × 10−11 cm2/W, while the two-photon absorption (β) coefficients were in the range of 6.5–68 cm/GW with |χ(3)| in the range of 10−9 e.s.u. The resultant dipole moments of these corroles were calculated theoretically and found to be 1.47–7.26 D depending on the nature of push-pull groups on the meso-phenyl substituents. 1–6 demonstrated excellent NLO activity due to their ‘push-pull’ design. Among the investigated corroles, 1 and 2 possess strong two-photon absorption coefficient and large values of χ(3) suggesting that the nonlinearity of corrole molecules highly depends on the electronic nature and number of meso-substituents. Corroles 1 and 2 possessing two acceptor and one donor moieties depicted superior NLO behavior as compared to corroles (3–6) with one acceptor and two donors due to strong electron withdrawing nature of pentafluorophenyl groups as well as higher singlet excited state lifetime and quantum yield.

ABCD Matrix formalism to Determine Nonlinear Refraction Coefficient by Z-Scan Technique

In this study, we revisit the popular method of measuring the nonlinear susceptibility of a material through Z-scan technique, introduced in 1990 by Sheik-Bahae and co-workers through a simple ray optics defined by the ABCD matrix formulation. The work therefore looks at the Z-scan measurement curves analysed through ray propagation in the medium and analysed through an aperture. The transmittance of a sample in the Z-scan technique is measured through a finite aperture in the far field, as the sample is scanned along the propagation direction (Z) of a focussed Gaussian beam. The sign and magnitude of nonlinear refractive index are easily deduced from the transmittance curve (Z-scan) using the theoretical model based on ABCD matrix formalism.

Growth of organic benzimidazole (BMZ) single crystal by vertical Bridgman technique and its structural, spectral, thermal, optical, mechanical and dielectric properties

Benzimidazole (BMZ) single crystal was successfully grown by the vertical Bridgman technique (VBT). The crystal system was identified and lattice parameters have been measured from the powder X-ray diffraction (PXRD) measurement. Fourier transforms infrared spectral studies have been carried out to find out the functional groups of BMZ crystal. The optical transmittance and the cut-off wavelength of BMZ were identified using UV–Vis NIR studies and the cut-off wavelength was found to be 294nm. The dielectric permittivity and dielectric loss as a function of frequency and temperature was measured for the grown BMZ crystal. Vickers microhardness analysis was carried out to identify the mechanical stability of the grown crystal. Chemical etching study was carried out using different etchants and the etch pit density (EPD) was calculated and compared. The third order nonlinear optical property of BMZ crystal was studied by using Z-scan technique with He–Ne laser (632.8nm). The magnitude of nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ3) have been found to be in the range of 10−11m2/W, 10−4m/W and 10−5esu respectively. Photoluminescence spectrum was recorded using a xenon lamp in the range of 330–585nm and it exhibits ultraviolet light emission.

Study on third order nonlinear optical properties of a metal organic complex—Monothiourea–cadmium Sulphate Dihydrate single crystals grown in silica gel

The third order nonlinear optical properties of Monothiourea–cadmium Sulphate Dihydrate crystal were measured using a He–Ne laser (λ=632.8nm) by a Z-scan technique. The magnitude of nonlinear refractive index (n2) and nonlinear absorption coefficient was found to be 4.4769×10–11m2/W and 1.233×10−2m/W respectively. The third order non-linear optical susceptibility χ(3) was found to be in the order of 3.6533×10−2esu. The negative sign of non-linear refractive index shows the self-defocusing nature of the gel grown crystal. The second-order molecular hyperpolarizability γ of the grown crystal is 1.2822×10−33esu. Laser damage threshold was measured by using an Nd: YAG laser (1064nm). Photoconductivity studies of the gel grown crystal revealed that the crystal possesses positive photoconducting nature. The results obtained from Z-scan, laser damage threshold and photoconducting studies reveal that the crystal can be a possible candidate material for photonics device, optical switches, and optical power limiting application.

Errata: Effect of concentration on the plasmonic absorption and optical nonlinearity of gold nanoparticles

The effect of concentration on the optical nonlinearity of gold nanoparticles is investigated. Gold nanoparticles were synthesized by nanosecond-pulsed laser ablation of a high-purity gold plate in distilled water. The size of nanoparticles was measured using dynamic light scattering (DLS) method and was calculated from full width half maximum of their plasmonic absorption peak using Mie theory. Different nonlinear characteristics of gold nanoparticles are observed by considering their effects under irradiation with a second harmonic beam of a continuous-wave low power Nd-YAG laser at 532 nm. Low-power optical limiting with low limiting threshold is obtained in the sample using different apertures at different points of the laser beam path. The nonlinear optical responses are characterized by measuring the intensity dependent refractive index of medium using the z-scan technique. Results show that the linear absorption coefficient and nonlinear refractive index of samples are increased with increasing the concentration of gold nanoparticles in distilled water. Increasing the intensity of the probe beam leads to increasing the magnitude of nonlinear refractive index.

Dielectric, optical and mechanical studies of phenolic polyene OH1 organic electrooptic crystal

Abstract 2-{3-[2-(4-Hydroxyphenyl) vinyl]-5, 5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile (OH1) phenolic locked polyene organic material has been synthesized by the Knoevenagel condensation method. OH1 single crystals were grown in methanol by a slow evaporation method. In order to avoid the multinucleation and reduce the metastable zone width, phosphoric acid is added in different concentrations. The linear optical property of OH1 crystal has been studied using UV–vis–NIR spectroscopy in the wavelength range 190–1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10 −12 m 2 /W), nonlinear absorption (10 −6 m/W) and third order nonlinear susceptibility (10 −6 esu) has been studied using a Z -scan technique. Dielectric property of OH1 crystal has been studied in frequency range 50 Hz–5 MHz. Photoluminescence spectrum was recorded using a xenon lamp in the range of 450–700 nm. Laser optical damage threshold of OH1 crystal was obtained (0.62 GW/cm 2 ) using a pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns.

Optical studies on picoseconds response of optical switching 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile organic NLO material

An organic push–pull chromophores 2-{3-[2-(3-methyl-4-methoxyphenyl)vinyl]-5,5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile(MOT2) was synthesized. The third order nonlinear optical property of MOT2 crystal was studied by using Z-scan technique with He–Ne laser (632.8nm). The magnitude of nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ3) have found to be in the range of 10−14m2/W, 10−7m/W and 10−8esu respectively. The multiphoton absorption and self defocusing effect were observed in z-scan open and closed aperture methods respectively. The response time of MOT2 crystal has found to be in the order of picoseconds, which is the essential requirement for the fabrication of optical switching. The optical transparency of MOT2 crystal was studied using UV–Vis–NIR spectroscopy and the reflectance, optical band gap (2.159ev), extinction coefficient, optical conductivity were calculated. The refractive index of MOT2 crystal was measured using Abbe’s refractometer and it is found to be 1.661. Photoluminescence study was carried out using Xenon lamp in a wavelength range of 450–700nm. Laser optical damage threshold of MOT2 crystal was calculated using pulsed Nd-YAG laser of 1064nm repetition rate of 10ns.

Investigation on the linear and nonlinear optical properties of a metal organic complex—Bis thiourea zinc acetate single crystal

The third order nonlinear optical properties of bis thiourea zinc acetate single crystal were measured using He–Ne laser (λ=632.8nm) by employing the Z-scan technique. The magnitude of nonlinear refractive index and nonlinear absorption coefficient were found to be −2.11×10−8cm2/W and −1.201×10−3cm/W respectively. The linear refractive index of the complex was measured by the Brewster angle method and was found to be 1.483. The third order non-linear optical susceptibility χ(3) was found to be in the order of 10−6esu. The negative non-linear absorption coefficient shows the defocusing nature of the complex which is an essential property required for the application in optical limiting application. The second harmonic generation efficiency of the complex was studied using the Powder Kurtz method and was found to be 1.5 times greater than that of KDP.

χ(3) measurement and optical limiting properties of metal complexes of thiourea using Z-scan

The third order NLO properties of thiourea and its metal complexes were measured using a 532 nm second harmonic of diode pumped Nd:YAG laser (1064 nm, 50 mW) by employing the Z-scan technique. The magnitude of nonlinear refractive index, nonlinear absorption coefficient and third order susceptibility was found to be in the order of 10 −8 cm 2 W −1, 10 −3 cm W −1 and 10 −6 esu respectively. The Z-scan reflects the negative nonlinearity of the samples and hence self defocusing nature is responsible for the optical limiting behavior in the regime of interest. The response time was found to be in the order of milliseconds.

Nonlinear optical susceptibilities of diglycinyl thiourea for frequency conversion and optical limiting applications

Organic nonlinear optical material diglycinyl thiourea (DGT) has been synthesized and single crystals have been grown from the aqueous solution by solvent evaporation technique. Powder second harmonic generation (SHG) study shows that DGT is 2.5 times efficient than KDP and is phase matchable. The third-order nonlinear optical and optical limiting properties of DGT have been investigated using a 532 nm second harmonics of diode-pumped Nd:YAG laser (1064 nm, 50 mW). The magnitude of nonlinear refractive index, nonlinear absorption coefficient and third-order susceptibility was found to be in the order of 10 −8 cm 2/W, 10 −3 cm/W and 10 −6 esu, respectively.

Non-linear optical properties of silver nanoparticles prepared by hydrogen reduction method

Silver nanoparticles have been prepared using hydrogen gas as the reducing agent for silver nitrate and poly(vinyl pyrrolidone) as the capping agent; the reaction was carried out at 70 °C for 3 h. The size of the nanoparticles was found to be about 20 nm as analyzed using transmission electron micrographs. The X-ray diffraction pattern revealed the face-centered cubic (fcc) structure of silver nanoparticles. The linear absorption of Ag nanoparticles, α, is obtained about 3.71 cm −1. The non-linear refractive indices of silver nanoparticles were defined by the z-scan technique using CW He–Ne laser ( λ = 632.8 nm) at different incident intensities. The magnitude of non-linear refractive index ( n 2) was measured to be in the order of 10 −7 (cm 2/W) with a negative sign. Therefore self-defocusing phenomena is taking placed for Ag nanoparticles.

Substituent Dependence of Third-Order Optical Nonlinearity in Chalcone Derivatives

The third-order nonlinear optical properties of derivatives of dibenzylideneacetone were investigated using the single beam z-scan technique at 532 nm. A strong dependence of third-order optical nonlinearity on electron donor and acceptor type of substituents was observed. An enhancement in χ(3)-value of one order of magnitude was achieved upon the substitution of strong electron donors compared to that of the molecule substituted with an electron acceptor. The magnitude of nonlinear refractive index of these chalcones is as high as of 10-11 esu. Their nonlinear optical coefficients are larger than those of widely used thiophene oligomers and trans-1-[p-(p-dimethylaminobenzyl-azo)-benzyl]-2-(N-methyl-4-pyridinium)-ethene iodide (DABA-PEI) organic compounds.

Large third-order optical nonlinearity and optical limiting in symmetric and unsymmetrical phthalocyanines studied using Z-scan

The third-order nonlinear optical and optical limiting properties of 2,3,9,10,16,17,23,24-octakis-(heptyloxy)-phthalocyanine, 2,3,9,10,16,17,23,24-octakis-(heptyloxy)-phthalocyanine zinc(II) ( symmetric) and 2(3)-(butane-1,4-dioic acid)-9(10),16(17),23(24)-tri tert-butyl phthalocyanine zinc(II) ( unsymmetrical) have been investigated using a continuous wave laser at 633 nm. We have employed the Z-scan technique to evaluate the sign and magnitude of nonlinear refractive index and the nonlinear absorption coefficient. Optical limiting based on nonlinear refraction was performed and limiting thresholds were estimated for all the three samples. The magnitude of the third-order nonlinearities measured were one of the highest reported in the cw regime till date. Unsymmetrical phthalocyanine had better limiting characteristics and its nonlinear coefficients were comparatively high. Results of the nonlinear optical studies performed with these organic dyes doped in Poly(methylmethacrylate) are also presented. Our studies indicate that these phthalocyanines are potential candidates for optical limiting applications in low power cw regime.