Nonlinear Refractive Index Of Samples Research Articles

The nonlinear optical properties of two dihydropyridones derived from curcumin.

Two dihydropyridone compounds are synthesized from curcumin using microwave radiation. Both compounds were identified by their melting points and 1HNMR spectra. The nonlinear properties viz., nonlinear absorption coefficients and nonlinear refractive index of both compounds were calculated at wavelength 473nm using the diffraction ring patterns and Z-scan techniques separately. The diffraction ring patterns evolved from circular symmetric to asymmetric due to convection current in the vertical direction. As a result of using Gaussian laser beam, the Fraunhofer approximation of the Fresnel-Kirchhoff diffraction, have led to successful simulation of the diffraction ring patterns with good quantitative and excellent qualitative agreements compared with experimental results. Optical limiting property has been tested in both compounds.

Thermally induced dispersive optical bistability in silver nanosuspensions produced by pulsed laser ablation method

The thermally induced optical bistability in prepared silver (Ag) nanosuspensions have been studied experimentally, using Fabry–Perot and Mach–Zehnder interferometry methods. Two Ag nanosuspensions of different sizes were produced by different fluences of pulsed laser ablation method in distilled water. The pulsed Nd:YAG laser of 7 ns pulse width, 1064 nm wavelength and different fluences was employed to produce Ag nanosuspensions. Experimental observations were performed by an ultraviolet–visible–near infrared spectrophotometry. Structure and size of prepared Ag nanoparticles were diagnosed using transmission electron microscope images. Fabry–Perot and Mach–Zehnder interferometry methods were used to carry out the optical bistability process in prepared Ag nanosuspensions. In two considered interferometers, the obtained phase shifts of the hysteresis loops based on the optical bistability are inversely proportional to the nonlinear refractive index of samples and thickness of Ag nanosuspensions cells. Results indicate that the induced thermal effect of the optical bistability can be tuned by modifying parameters such as the nonlinear refractive index and applied interferometry methods. Hence, a desirable situation for the thermo-optical effects of the optical bistability can be easily realized in Ag nanosuspensions.

Investigation of nonlinear optical behavior of creatinine for measuring its concentration in blood plasma

Since creatinine reflects the Kidneys function in the human body, the accurate measuring methods to assess the concentration of creatinine in blood plasma are important. Colorimetric method is usually used to measure the concentration of creatinine in blood plasma. In this paper, we have applied Z-scan technique to investigate the nonlinear behavior of creatinine of blood plasma. The samples include different concentrations of creatinine. The concentration of creatinine directly changes the nonlinear refractive index of samples. As a result, this method can be used to measure the creatinine concentration of blood plasma.

A method for measuring the nonlinear refractive index from the contrast of an amplitude object image in the optical scheme with phase Zernike filters based on electronic Kerr nonlinearity

We propose a method for determining the nonlinear refractive index from the image contrast of amplitude objects in the phase-contrast scheme with a sample acting as a phase Zernike filter based on the electronic Kerr nonlinearity. This method implies the measurement of the calibration dependence of the contrast of an amplitude object image on the laser pulse energy for a test sample with a known nonlinearity and makes it possible to find the nonlinear refractive index of samples under study using a single laser pulse.

Low power continues wave nonlinear optics in red BS dye doped PVA thin film

Effect of laser beam intensity and red BS dye on the nonlinear optical properties of red BS dye doped commercial Polyvinil Alcohol (PVA) film is studied employing different techniques. Nonlinearity measurement was performed using the second harmonic of a continuous Nd-YAG laser beam at 532nm wavelength and 50mW power. The nonlinear refractive index and nonlinear absorption coefficient of samples were measured using Z-scan method. Second order nonlinear refractive index of samples was measured to be in the range of 10−5cm2/W which was increased with increasing the amount of dye in the films structure. Both nonlinear refractive index and absorption coefficient of samples increased with increasing the amount of dye in the structure of the films and laser intensity.

Nonlinear optical characterization of the Ag nanoparticles doped in polyvinyl alcohol films

The effect of silver nanoparticles doped in polyvinyl alcohol (PVA) on the nonlinear optical properties of composite films is studied experimentally. Samples are PVA films of 0.14 mm thickness doped with different concentrations of silver nanoparticles. Nonlinear optical properties of doped polymer films are studied experimentally employing Z-scan techniques. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at 532 nm wavelength and 45 mW power. The effect of nonlinear refractive index of samples is obtained by measuring the profile of propagated beam through the samples and their nonlinear refractive index is found to be negative. The nonlinear absorption coefficient is calculated using open aperture Z-scan data while its nonlinear refractive index is measured using the closed aperture Z-scan data, leads to measuring the third order susceptibility |χ(3)|. Real and imaginary parts of the third-order nonlinear optical susceptibility |χ(3)| are decrease with increasing the concentration of Ag nanoparticles in the films. The values of thermo-optic coefficient are determined at different concentrations of silver nanoparticles for samples.

Effect of radio frequency plasma treatment on the nonlinear refractive index and absorption coefficient of red lake doped polyvinyl chloride film

Effect of plasma treatment on the nonlinear optical properties of red lake doped commercial polyvinyl chloride (PVC) film is studied employing different techniques. PVC films were exposed to low pressure plasma from 5 to 15 min. Nonlinearity measurement was performed using the second harmonic of a continuous Nd-YAG laser beam at 532 nm wavelength and 50 mW power. The optical limiting behavior of samples was investigated by measuring their transmission at different beam intensities. For all pristine and plasma treated samples optical limiting started at laser beam power of 12 mW. The nonlinear refractive index and nonlinear absorption coefficient of plasma treated samples were measured using Z-scan method. Second order nonlinear refractive index of samples was measured to be in the range of \(10^{-8}\,\hbox {cm}^2/\hbox {W}\) which was decreased after plasma treatment. Experimental results show that real and imaginary parts of nonlinear susceptibility are strongly influenced by plasma treatment.

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.

Effect of thickness on the optical nonlinearity of gold colloidal nanoparticles prepared by laser ablation

The effect of thickness on the nonlinear optical properties of Au nanoparticles which produced by laser ablation of high purity gold bulk in distilled water were investigated by employing different optical techniques. Experiments were performed on the 0.3, 0.6, and 1 mm thickness cells of Au nanoparticles-fluid. The effect of nonlinear refractive index of samples on the laser beam broadening was observed. The optical limiting behavior of samples is investigated by measuring the transmitted intensity of the laser beam through the samples. The third order nonlinearity of Au nanoparticles-fluid was measured by using Z-scan data. Results show a positive second order refractive index and absorption coefficient for Au nanoparticles-fluid that are increased in due of increasing the thickness of the cells. The magnitudes of both real and imaginary parts of third order susceptibility of samples are increased by increasing the thickness.

Characterization of light-induced modification of the nonlinear refractive index using a one-laser-shot nonlinear imaging technique

We report the exploitation of a one-laser-shot measurement technique to study photo-induced effects in semiconductor-doped glasses. The technique, based on the use of a phase object in a 4f coherent imaging system, allows one to characterize the kinetics of the nonlinear refractive index of samples versus the light exposure time.