Value Of Third-order Susceptibility Research Articles

Enhanced dielectric, EMI shielding effectiveness, linear and nonlinear optical properties of CdO/SnO2 nanocomposites

In recent days, new advanced nanomaterials are necessary to satisfy the required properties in various electronic and energy applications. This research work concentrates on producing the new nanocomposites with many enhanced electronic and dielectric properties of multifunctional devices. The samples CdO, CdO/SnO2, and PVP capped CdO/SnO2 nanocomposite have been synthesized by microwave irradiation method. The effect of incorporation of SnO2 and PVP with CdO for phase changes, morphological, linear and nonlinear optical properties, LED applications, dielectric properties, and electromagnetic interference shielding efficiency (EMI). XRD phase study confirms that the nanocomposite contains both a cubical structure of CdO and an orthorhombic structure of SnO2. PVP SEM and TEM images show changes in morphology as nanorod in CdO/SnO2/PVP due to heterogeneous nucleation effect and reduction in particle size. PL study reveals that the enrichment of photoluminescence property in CdO/SnO2/PVP nanocomposite due to the incorporation of PVP and SnO2, which produce defects in the lattice. CIE chromaticity diagram represents that the fabricated nanocomposites are suitable in designing a light-emitting diode. Nonlinear refractive index and third-order susceptibility values are more significant in CdO/SnO2/PVP nanocomposite than CdO and CdO/SnO2. The effect of SnO2 and PVP with CdO in dielectric constant, dielectric loss, electrical conductivity, and electromagnetic interference shielding efficiency were discussed. Finally, all present results ensured that the incorporation of SnO2 and PVP with CdO will enhance the optical, electronic and dielectric properties.

Measurement of non-linear optical properties in graphene oxide using the Z-scan technique.

We report the value of non-linear optical parameters in graphene oxide (GO) using the Z-scan technique. The value of the non-linear refractive index η2, non-linear absorption coefficient β and the complex value of third order susceptibility χ(3) in samples with different concentrations of GO diluted in distilled water were determined. The value of these parameters were obtained directly from the measurement of normalized transmittance of each sample as a consequence of its non-linear response when are exposed to electromagnetic radiation from a Nd:YAG laser emitting at 532nm in CW mode. In addition, we found that the parameters η2, β and χ(3) growth by increasing excitation laser power, where β showed an high order of magnitude around ~10-2 cm/W.

Optical behaviour of nematic liquid crystal doped with carbon dot in the nonlinear optical regime

We delve into the effect of carbon dot (c-dot) doping at different concentrations (0.1, 0.2, 0.4, and 1 wt%) on the third order nonlinear optical properties of a nematic liquid crystal (NLC). C-dots were synthesized by the thermal decomposition of ammonium citrate salt. The size and morphology of prepared c-dots were confirmed by the TEM micrograph. Nonlinear optical properties of c-dot doped liquid crystal were investigated by the z-scan method using a Q-switched Nd: YAG laser delivering 7 ns pulse at 532 nm wavelength. A phenomenal increase in the nonlinear absorption coefficient, βeff, was observed for 0.2 wt% c-dot doped liquid crystal. There is an enhancement in the value of third order susceptibility, χ(3), of the order of 10 for the doped liquid crystal. An increase in the third order nonlinear optical absorption coefficient implies a better optical limiting characteristic than the pristine LC. The optical limiting threshold value of 0.2 wt% c-dot doped LC is found to be 1.23 J/cm2. We determine for the first time that c-dot doping in NLC leads to a significant improvement of the nonlinear optical properties compared to pure LC. The results indicate that the system under study could be a promising candidate for nonlinear photonic devices and optical limiters.

An investigation on optical-nonlinear and optical limiting properties of CdS: an effect of Te doping concentrations for optoelectronic applications

In current article authors aim is to present an insight on structural, opto-nonlinear-limiting properties of Cadmium sulfide (CdS) thin films affected by various concentrations of tellurium (Te) doping. Hence, the thin films of pure and Te:CdS were fabricated by spray pyrolysis technique by keeping the substrate at 300 °C. X-ray diffraction and FT-Raman spectroscopy analyses confirmed the hexagonal phase of CdS. The values of Lave, ρave and eave are found in range of 18–20 nm, 2.6–3 nm−2 and 1.7–1.9, respectively. Furthermore, the energy dispersive X-ray spectroscopy/scanning electron microscopy mapping (SEM) confirmed the presence and homogeneous doping of Te in CdS. SEM study shows that the fabricated films are free from any pin holes and possess very fine nanostructures. The optical transparency of grown films was noticed ~ 70%, which is quite impressive for colored materials. The absorption index, refractive index values are found in range of 0.04 to 0.25, 1.25 to 3.2 in 200 to 2500 nm wavelength region. The direct energy gap of CdS was noticed to be reduced from 2.44 to 2.35 eV (ΔEg = 0.09) with Te doping content. Photoluminescence emission spectra contains an intense green emission band at ~ 528 ± 4 nm. The dielectric constant and optical conductivity were noticed in range of 1.5 to 10 and 0.02 to 0.6 (× 105), respectively. The values of third order susceptibility and nonlinear refractive index was found of the order of 10−10 esu. The output power of the 532 nm laser passed from films is found to be reducing with increasing the Te content in CdS films. Hence, the deposited films of Te:CdS will be more applicable as optical limiter in sensor device protection from intense lights.

Study of nonlinear optical susceptibility of defective shell spherical quantum dot

In this paper, the nonlinear third order susceptibility of proposed new GaN/AlGaN defective shell spherical quantum dot is calculated by using the effective mass approximation. The new proposed nanostructure is containing defective shell surrounding with two spherical well. The size of quantum dot, defective shell thickness, defect position and potentials of defect region have a significant effect on third order optical susceptibility. The results are shown that with increasing of quantum dot size the third order susceptibility is increased and resonance wavelength is red shifted due to quantum confinement effect. Also, with increasing of defective shell thickness nonlinear susceptibility is increased. The increasing of third order susceptibility and red shifting of resonance wavelength are occurring with increasing of defect potential too. The largest value of third order susceptibility is achieved when in the symmetric condition of defect position, the defect potential becomes equal to barrier potential.

Third-order nonlinear optical properties of organic azo dyes by using strength of nonlinearity parameter and Z-scan technique

In this paper, two chemically synthesized organic azo dyes, 2-(2,5-Dichloro-phenyazo)-5,5-dimethyl-cyclohexane-1,3-dione (azo dye (i)) and 5,5-Dimethyl-2-tolylazo-cyclohexane-1,3-dione (azo dye (ii)), have been studied from optical Kerr nonlinearity point of view. These materials were characterized by Ultraviolet-visible spectroscopy. Experiments were performed using a continous wave diode-pumped laser at 532nm wavelength in three intensities of the laser beam. Nonlinear absorption (β), refractive index (n2) and third-order susceptibility (χ(3)) of dyes, were calculated. Nonlinear absorption coefficient of dyes have been calculated from two methods; 1) using theoretical fits and experimental data in the Z-scan technique, 2) using the strength of nonlinearity curves. The values of β obtained from both of the methods were approximately the same. The results demonstrated that azo dye (ii) displays better nonlinearity and has a lower two-photon absorption threshold than azo dye (i). Calculated parameter related to strength of nonlinearity for azo dye (ii) was higher than azo dye (i), It may be due to presence of methyl in azo dye (ii) instead of chlorine in azo dye (i). Furthermore, The measured values of third order susceptibility of azo dyes were from the order of 10−9esu. These azo dyes can be suitable candidate for optical switching devices.

Measurement of third order susceptibility by nonresonant nondegenerate four wave mixing in polymer embedded cadmium sulfide quantum dot systems

Abstract We report clear evidence of third order nonlinearity χ(3) in polymer embedded cadmium sulfide quantum dot system as a result of nonresonant nondegenerate four frequency mixing. We notice thickness dependent enhancement of nonlinear absorption with increase in incident intensity of light. Two pump beams (λ = 1064 nm) were oppositely directed into the sample and to receive phase conjugated signal, a probe beam was focused at the point of intersection on the sample. In the conditions satisfying self diffraction phenomena, we have measured change in refractive index as a function of incident power. We have observed very high value of third order susceptibility (χ(3) ∼ 10−7 e.s.u.) and predict figure of merit as high as ∼1.9 for the thinnest quantum dot sample (0.54 μm). Nonlinear susceptibility drops by nearly 10 times for the thickest sample (1.211 μm) due to considerable suppression in nonlinear absorption.

OPTICAL NONLINEARITY OF Au METAL NANOPARTICLE DISPERSED (Ba,Sr)TiO3 THIN FILMS

Nearly spherical Au nanoparticles of about 3.83 nm diameter were embedded into the ( Ba , Sr ) TiO 3 matrix using alternating sputtering method, showing the characteristic surface plasmon resonance absorption band at 571 nm. Dispersion in the third-order optical nonlinearity was investigated at several wavelengths from 450 to 680 nm around the resonance peak by a single beam Z-scan technique with a wavelength tunable picosecond laser system. The real and imaginary parts of third-order nonlinear susceptibility were resolved and the relative contributions are quantitatively compared at each wavelength. The maximum absolute value of third-order susceptibility as large as 4.312 × 10-8 esu was obtained at the surface plasmon frequency. The temporal response was also characterized by the femtosecond time-resolved optical Kerr gate measurement and the nonlinear response time was evaluated to be 192 fs at the laser wavelength of 800 nm.

Optical Properties of Au Nanoparticle Dispersed (Ba,Sr)TiO3 Thin Films

Au nanoparticles dispersed (Ba,Sr)TiO3 thin films were fabricated using alternating sputtering method. With the nominal thickness of Au layer of 1 nm, the spherical Au particles of 3.83 nm size were obtained showing the spatial distribution referred to a Maxell-Garnett type effective medium geometry. The film shows the characteristic surface plasmon resonance absorption band at 571 nm. Based on the effective medium theory, the linear optical functions of the films were characterized. The third-order optical nonlinearity was analyzed by a single beam Z-scan technique with a picosecond pulse laser. The real and imaginary parts of third-order susceptibility can be resolved at several wavelengths around the SPR by virtue of wavelength tunable optical parametric generator. The maximum absolute value of third-order susceptibility as large as 3.847 × 10− 8 esu were obtained at the SPR frequency.

Third-order nonlinear optical properties and two-photon absorption in branched oligothienylenevinylenes

We report measurements of the third-order susceptibilities and two-photon absorption in branched oligothienylenevinylenes derivatives C 42H 62S 2, C 114H 174S 6, C 252H 366N 3O 6P 3S 12, using degenerate four wave mixing (DFWM) technique at λ=532 nm in picosecond regime. All the studied compounds show large third-order nonlinear optical properties with comparison with known materials such as, polydiacetylene, octupolar molecules and their dipolar subunits. We show the influence of the number of branches on the benzene cycle. We demonstrate that the values of third-order susceptibilities χ 〈3〉 and two-photon absorption coefficients β increase as the number of branches increase. As consequence the studied complexes can be very interesting for optical limiting applications.