Nonlinear absorption and refractive index of a Brillouin-scattered mode in magnetoactive centrosymmetric semiconductor plasmas

1994 ◽  
Vol 49 (8) ◽  
pp. 5246-5252 ◽  
Author(s):  
Swati Dubey ◽  
S. Ghosh
2008 ◽  
Vol 22 (22) ◽  
pp. 3877-3887
Author(s):  
M. SINGH ◽  
D. JOSEPH ◽  
S. DUHAN

The nonlinear optical parameters (absorption coefficient and refractive index) of semiconductor-plasmas subjected to a transverse magnetic field have been investigated analytically. By employing the coupled-mode scheme, an expression of third-order optical susceptibility and resultant nonlinear absorption and refractive index of the medium are obtained. The analysis has been applied to both cases, viz., centrosymmetric (β = 0) and noncentrosymmetric (β ≠ 0) in the presence of magnetic field. The numerical estimates are made for InSb crystal at liquid nitrogen temperature duly irradiated by a 10-nanosecond pulsed 10.6 μm CO 2 laser. The influence of doping concentration and magnetic field on both the nonlinear absorption and refractive index has been explored, and the results are found to be well in agreement with theory and experiment. Analysis further establishes that absorption coefficient and refractive index can be controlled with precision in semiconductors by the proper selection of doping concentration and an external magnetic field, and hence these media may be used for fabrication of fast cubic nonlinear optical devices under off-resonant transition regime.


2011 ◽  
Vol 20 (02) ◽  
pp. 183-191 ◽  
Author(s):  
FRYAD Z. HENARI ◽  
ABDULLAH M. ASIRI

We report results from investigations of the nonlinear refractive index and nonlinear absorption coefficient of (2E)-3-[4-(Dimethylamino)phenyl]-1-(2,5-dimethylthiophen-3-yl)prop-2-en-1-one and (2E)-3-(3,4-Dimethoxyphenyl)-1-(2,5-dimethylthiophen-3-yl) prop-2-en-1-one using Z-scan technique with a continuous wave (cw) laser at wavelengths 488 nm and 514 nm. The nonlinear refractive index and nonlinear absorption coefficient of both samples were evaluated. The origin of the nonlinear effects was discussed. Optical limiting based on light induced nonlinear refractive index variation is demonstrated. The limiting thresholds were estimated for both samples. The results suggested that these materials offer promise as candidates for optical limiting and optical devices in the low power regime.


2020 ◽  
Author(s):  
Ratna Agrawal ◽  
Ravi Vanshpal ◽  
Swati Dubey ◽  
S. Ghosh

1992 ◽  
Vol 247 ◽  
Author(s):  
Christopher S. Winter ◽  
S. N. Oliver ◽  
C A. S. Hill

ABSTRACTThe nonlinear refractive index, linear and nonlinear absorption coefficients of a number of nickel dithiolene-doped PMMA polymers have been measured. Nonlinear refractive indices up to about 10−8 cm−2/KW were observed, with figures of merit defined by δnsat/αλ and Reχ(3) / Im χ(3) within acceptable device limits.


2012 ◽  
Vol 05 ◽  
pp. 277-283 ◽  
Author(s):  
M. H. MAJLES ARA ◽  
Z. DEHGHANI

Titanium dioxide (titania) is a cheap, nontoxic and highly efficient photocatalyst being extensively applied for the degradation of organic pollutants, air purification, water splitting, reduction of nitrogen to ammonia, and optical devices due to its optical behaviors. The third-order nonlinear optical properties of TiO 2/ PS nano-composite were studied by means of single beam transmission technique, using a continuous-wave (CW) He - Ne laser beam with a wavelength of 632.8 nm with three different incident intensities. The magnitude and sign of the third-order nonlinear refractive index ( n 2) and nonlinear absorption (β) of TiO 2/ PS nano-composite were determined by use of both the closed-aperture and opened-aperture z -scan techniques. Z -scan technique, developed by Sheik-Bahae et al., has been used widely in material characterization. A single-beam (also called z -scan method) for measuring the sign and magnitude of nonlinear refraction that has simplicity and very high sensitivity has been reported recently. Optical limiting property of TiO 2/ PS nano-composite is studied. The positive sign obtained for nonlinear refractive index indicated that there is a self-focusing effect in the sample. The nonlinear refractive index was in order of 10-8 (cm2/W) and the nonlinear absorption coefficient was obtained in order of 10-2 (cm/W) with negative sign. The values of nonlinear refractive index and nonlinear absorption coefficient are enhanced by decreasing the intensity.


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