Nonlinear Optical Refraction and Absorption Features of Methyl Orange Dye in Polar Solvents.

Herein, we report the nonlinear optical (NLO) refraction and absorption features of azo dye namely, methyl orange (MO) dissolved in ethanol, methanol, acetone, 1-propanol, DMF and DMSO. The UV-Visible absorption study reveals that the maximum absorption spectrum of MO dye appeared towards longer wavelength by increasing the solvent polarizability is the result of red shift or bathochromic shift. The Z-scan method is utilized to measure the third-order NLO features of MO dye in different polar solvents. A continuous wave laser with 5-mW power and an excitation wavelength of 405 nm is employed in the Z-scan technique. The NLO features including nonlinear index of refraction (n2), nonlinear coefficient of absorption (ß) and third-order NLO susceptibility (χ3) are calculated to be the order of 10-7 cm2/W, 10-2 cm/W and 10-7 esu, respectively. The NLO index of refraction shows peak-valley transmittance is the result of self-defocusing and NLO absorption coefficient exhibits both positive and negative nonlinearity owing to saturable absorption (SA) and reverse saturable absorption (RSA). The effect of solvent polarizability and dipole moment on third-order NLO susceptibility of MO dye is discussed. Based on the experimental results, an azo dye MO appears to be a promising option for NLO applications in the future.

Solvent Media on Nonlinear Optical Properties of Triarylmethane Dye via Facile Z-Scan Method.

Solvent environment on third-order nonlinear optical (TNLO) features of triarylmethane dye namely, basic blue 7 in different solvents is reported herein using 650 nm diode laser with continuous wave mode. The basic blue 7 dye is dissolved in different solvent media including ethanol, methanol, dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). The influence of solvent characteristics such as solvent polarizability and dipole moment on solute molecule is discussed. TNLO characteristics such as nonlinear optical index of refraction, nonlinear optical coefficient of absorption, real and imaginary components of the TNLO susceptibility are measured to be the order of 10‒7 cm2/W, 10‒3 cm/W, 10‒6 esu and 10‒7 esu, respectively. The dye exhibits large TNLO susceptibility by dissolving in DMSO. The TNLO susceptibility of basic blue 7 dye is measured to be the order of 10‒6 esu. The overall results revealed that the basic blue 7 dye is suitable material for optoelectronics applications.

Saturable and Reverse Saturable Absorption Features of Lissamine Green Dye in Different Solvent Media.

Organic dyes have shown a remarkable nonlinear optical (NLO) characteristics under low power laser regime because of chemical stability, large nonlinearity and high susceptibility. With this view in mind, herein we report the third-order NLO features of lissamine green dye using 5 mW power laser with operating wavelength of 650 nm. The lissamine green dye is dissolved into various polar solvents such as ethanol, methanol, acetone and DMSO. The closed aperture Z‒scan approach discloses the information about nonlinear refractive index, whereas the open aperture Z‒scan technique provides the information about nonlinear absorption coefficient. The closed aperture curve shows the peak-valley transmittance is the result of self-defocusing nonlinearity and the open aperture transmittance curve switchover from saturable absorption to reverse absorption in high polar solvent due to polarizability and dipole moment. The third-order NLO features such as nonlinear refractive index (n2), nonlinear absorption coefficient (ß), real and imaginary features of third-order NLO susceptibility of the dye is calculated to be the order of, 10-7 cm2/W 10-3 cm/W, and 10-7 esu respectively. The correlation between solvent polarizability and dipole moment on lissamine green dye is discussed. The results are revealed that the lissamine green dye is a good candidate for NLO applications.