The excited state absorption cross-section of 5,5′-dichloro-11-diphenyl-amino-3,3′-diethyl-10,12-ethylinethiatrica rbocyanine perchlorate (IR140) have been measured by using a single beam transmission technique. Z-scan experiments have been used to find out a few nonlinear parameters. The excited state relaxation times have also been measured by using laser induced transient grating (LITG) technique.

Prem Ballabh Bisht

Department Of Physics

Umakanta Tripathy

R. Justin Rajesh

A. Subrahamanyam

Diffraction

Electric fields

Fluorescence

Light absorption

Parameter estimation

Phase shift

Refractive index

Aromatic compounds

Curve fitting

Electron energy levels

Nonlinear optics

NONLINEAR PARAMETERS

Dyes

Excited state absorption

EXCITED STATE RELAXATION

LASER INDUCED TRANSIENT GRATING (LITG) TECHNIQUES

Nonlinear refractive index

z-scan

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Optical nonlinearity of organic dyes as studied by Z-scan and transient grating techniques

Proceedings of the Indian Academy of Sciences: Chemical Sciences

The optical nonlinear refractive and absorptive parameters of the dye N,N′–Bis(2,5,-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide (DBPI) in 96% sulphuric acid have been obtained by a single closed-aperture (CA) Z-scan technique with picosecond pulses at the wavelength of 532 nm. Here a theoretical model was used to deduce both the refractive and absorptive optical nonlinearity present simultaneously in the CA Z-scan profile. Under the range of concentrations and energies studied here, we found that the effect of saturable absorption (SA) is dominating at higher concentrations (i.e. 1.0 × 10−3 M), whereas the reverse saturable absorption (RSA) effect was taken over at dilute concentrations (i.e. 1.0 × 10−4 M and 1.0 × 10−5 M). The dominance of absorptive nonlinearity over the refractive nonlinearity results in a low value of the refractive cross-section (σr). A relative increase in the value of σr is observed with decrease in the dye concentration. Mathematical modeling of CA Z-scan profiles of DBPI shows the existence of peak-valley or valley-peak structure depending upon the contribution of nonlinear absorption. The optical nonlinear parameters have also been estimated by theoretical simulation studies as a function of wavelength and compared with the experimental results. The dye DBPI has been found to be suitable as an important highly photostable molecule for photonic devices in the visible region (400–630 nm). © 2017 Elsevier B.V.

Optical Materials

Experimental and theoretical simulation studies on picosecond closed-aperture Z-scan profiles of N,N′–Bis(2,5,-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide (DBPI)

Two dye pairs suitable for energy transfer along with a photostable dye have been studied by using the closed-aperture (CA) Z-scan technique under pulsed and cw pumping. Here we use a theoretical model to elucidate the refractive and absorptive nonlinearity present simultaneously in the CA Z-scan proffle. A separate open-aperture (OA) Z-scan study has been carried out to compare the nonlinear absorption parameters obtained from the CA Z-scan technique. At a fixed pumping wavelength, values of optical nonlinear parameters increase with the absorbance of dyes. It is found that the sign of refractive nonlinearity is dependent on the irradiance and the pulse width of the pump beam. In addition to the contribution of the third-order optical nonlinearity, various other mechanisms such as fifth-order nonlinearity, population relaxation to triplet states, and thermal effects are discussed here. © 2007 Optical Society of America.

Journal of the Optical Society of America B: Optical Physics

Influence of pulsed and cw pumping on optical nonlinear parameters of laser dyes probed by a closed-aperture Z-scan technique

Diffraction efficiency of laser induced transient grating (LITG) for (DBPI) has been experimentally measured in solutions of benzene and dimethyl sulfoxide. Third-order nonlinear susceptibility (X(3)) values have been obtained from these measurements and have been compared to those obtained from theory. Further, the relaxation time of DBPI has been estimated by measuring the decay profiles of the LITG. © 2002 Published by Elsevier Science B.V.

Chemical Physics Letters

Theoretical and experimental studies on photophysical parameters of N, N′ -bis(2,5, -di-tert-butylphenyl)-3,4:9-10-perylenebis(dicarboximide) (DBPI) by using transient grating technique

Transient gratings are produced by placing a sample in the interference region of two intersecting intense laser beams. The optical constants of the sample change due to the spatially modulated interference field. Several interesting phenomena that occur in the excited state of organic molecules and in semiconductors can be studied by using the transient grating technique. Theoretical simulations are used as an additional tool to verify some of the experimental results that give signatures of the technique for standardization of the obtained results. A brief description of these phenomena along with an example is given here.

Research on Chemical Intermediates

Relaxation processes using transient grating technique

Optics Communications

Theoretical study on the closed-aperture Z-scan curves in the materials with nonlinear refraction and strong nonlinear absorption

Investigation of optical nonlinearities of azo nickel chelate compound by the Z-scan technique

Springer Series in Optical Sciences

Nonlinear Optical Effects and Materials

Journal	Proceedings of the Indian Academy of Sciences: Chemical Sciences
Publisher	Indian Academy of Sciences
Open Access	No