Transient multiple diffraction rings induced by ultrafast laser from chinese tea

He, K. X.; Abeleldayem, H.; Sekhar, P. Chandra; Venkateswarlu, P.; George, M. C.

doi:10.1016/0030-4018(91)90303-u

Cited by 18 publications

(6 citation statements)

References 7 publications

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“…The simulation results show that the stable diffraction pattern on the screen consisting of pronounced squeezed light rings is formed over a period of time and then is nearly unchanged until the end of the observation. This drastic deviation of vertical symmetry of the diffraction rings has been reported in some experimental data in the literature [14][15][16][17][18][19][20].…”

Section: Theoretical Modelsupporting

confidence: 77%

“…The lower portion of the beam is not affected by the natural convection currents as severely as the upper portion and the upward motion of the liquid reduces the refractive index gradient of the sample in the upper half part of the beam. As a result, the far-field intensity ring patterns of the Gaussian laser beam propagating through the liquid become squeezed from the top instead of remaining perfectly round [14][15][16][17][18][19][20]. It was reported that the cross-sectional pattern (concentric rings) of the collapsed laser beam could be an indication of the onset of convection caused by the beam [20].…”

Section: Introductionmentioning

confidence: 99%

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Spatial self-phase modulation of a laser beam propagating through liquids with self-induced natural convection flow

Karimzadeh

2012

J. Opt.

103

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In this work, the results of experimental and theoretical investigations of diffraction ring patterns are reported. Diffraction rings are formed due to the self-phase modulation of a continuous wave laser beam propagating through a solution of dye in ethanol. The self-phase modulation of the laser beam is the result of the changes in the refractive index due to the heating of the sample by a small absorbed fraction of the laser power. To find the thermal nonlinearity inside the liquid irradiated by a Gaussian laser beam, we have solved the heat transfer equation including conduction and convection effects in a liquid medium. The temporal dynamics and structural characteristics of the diffraction ring patterns are studied theoretically on the basis of a Fresnel-Kirchhoff diffraction integral in the approximation of an optically thin absorbing medium. The simulation results show that when a Gaussian laser beam is transmitted through a liquid medium the intensity distribution pattern in the far-field first forms a series of circular diffraction rings, but after a period of time the rings change to half circular symmetry due to convection.

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Section: Theoretical Modelsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Spatial self-phase modulation of a laser beam propagating through liquids with self-induced natural convection flow

Karimzadeh

2012

J. Opt.

103

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“…If the observed nonlinearity in the various Hibiscus Sabdariffa-H 2 O solutions is of a Kerr type in the nanosecond regime, it would certainly be of an additional nature in the pico and sub-pico regimes. As pointed out by Zhang et al [25] and He et al [26] in their studies of Chinese tea dye solutions with both a He-Ne and a CW mode-locked Nd:YAG (532 nm, 70 ps) lasers, the large observed nonlinearity was attributed to the pull of higher refractive index molecules into regions of high optical density by light pressure as well as to their reorientation and redistribution in the tea dye solution.…”

Section: Experiments and Discussionmentioning

confidence: 88%

“…The nonlinear optical properties, in addition to the optical limiting, were investigated by z-scan technique, which has the advantages of simplicity and high sensitivity, as well as enabling simultaneous measurement of the magnitude and sign of the nonlinear refractive index and the nonlinear absorption coefficient of the samples [16][17][18][19][20][21][22][23][24][25][26][27]. Basically, the method consists of translating a sample through the focus of a Gaussian beam and monitoring the changes in the far field intensity pattern (Fig.…”

Section: Experiments and Discussionmentioning

confidence: 99%

Z-scan and optical limiting properties of Hibiscus Sabdariffa dye

et al. 2014

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The intensity-dependent refractive index n 2 and the nonlinear susceptibility v (3) of Hibiscus Sabdariffa dye solutions in the nanosecond regime at 532 nm are reported. More presicely, the variation of n 2 , b, and real and imaginary parts of v (3) versus the natural dye extract concentration has been carried out by z-scan and optical limiting techniques. The third-order nonlinearity of the Hibiscus Sabdariffa dye solutions was found to be dominated by nonlinear refraction, which leads to strong optical limiting of laser.

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“…It has been observed in pure solvents (e.g., water, acetone, and anhydrous ethanol), plastics, wax and ice. [1][2][3] Interference rings induced by single-wavelength lasers were reported much earlier (e.g., liquid crystals, [4][5][6] tea, [7] nano-material suspensions, [8][9][10][11][12][13][14][15][16][17][18] and organic solvents). [19,20] There are mainly two models to explain interference rings in liquids: the thermal lens effect [8,16,19] and the electronic third-order nonlinear selfphase modulation.…”

Section: Introductionmentioning

confidence: 82%

Asymmetric coherent rainbows induced by liquid convection*

Shi¹,

Qian²,

Sun³

et al. 2021

Chinese Phys. B

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Coherent rainbows can be formed by focusing white-light laser into liquids. They are bilaterally symmetric interference rings with various shapes. Such interference rings arise from the temperature distribution of the liquid induced by laser heating, i.e., thermal lens effect, which changes the refractive index locally and thus the optical path difference. The up–down asymmetry of the interference rings is caused by convection in the liquid. With the increase of the viscosity, the interference rings change their shape from oval to circular shape. After a shutter is opened and the laser shines into the liquid, the interference rings are circular at the beginning. As time goes on, they gradually turn into anoval shape. Let the liquid go a free-fall at the beginning, the interference rings remain circular. All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect. We also numerically simulate the two-dimensional heat conduction with and without convection, whose results agree well with our experimental observations.

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Transient multiple diffraction rings induced by ultrafast laser from chinese tea

Cited by 18 publications

References 7 publications

Spatial self-phase modulation of a laser beam propagating through liquids with self-induced natural convection flow

Spatial self-phase modulation of a laser beam propagating through liquids with self-induced natural convection flow

Z-scan and optical limiting properties of Hibiscus Sabdariffa dye

Asymmetric coherent rainbows induced by liquid convection*

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