R. Vijaya

Bio: R. Vijaya is an academic researcher. The author has contributed to research in topics: Four-wave mixing & Phase conjugation. The author has an hindex of 2, co-authored 2 publications receiving 14 citations.

Nonresonant third‐order optical response of polyphenyl acetylene

Abstract: Optical phase conjugation by degenerate four‐wave mixing in samples of pristine and iodine‐doped polyphenylacetylene at ruby laser wavelength (694.3 nm) is reported here. The nonresonant values of the third‐order optical susceptibility χ(3) are determined from the measurements of reflectivity of phase conjugate signals.

The second and third order non-linear optical properties of liquid crystalline polymers

Abstract: The second and third order non-linear optical susceptibilities of several donoracceptor substituted side chain polymers, some of which exhibit mesophases, will be reported. The susceptibilities were measured by harmonic generation from thin films, typically 0·5 μm thick, at a fundamental wavelength of 1064 nm and 1579 nm. For second harmonic generation, the spin coated films were contact poled on a glass substrate with an interdigited electrode pattern. Typical values obtained were χ(2) 31 = 1 × 10−9 esu and χ(2) 33 = 3 × 10−9 esu, the largest value was χ(2) 33 = 6·3 × 10−9 esu. The difficulty in deriving reliable second order structure-property relations because of the large effect which the contact poling process has on the non-linear optical susceptibility of the films will be highlighted. The highest χ(3) value of 5·8 × 10−12 esu obtained from an amorphous film of a polymer with an asymmetrically substituted azo side group is comparable with the susceptibility of more typical third order non-...

Third-Order Nonlinear Optical Properties of Substituted Polyphenylacetylenes

Abstract: Third-order harmonic generation (THG) and electroabsorption (EA) in substituted polyphenylacetylenes (PPAs) which are examples of onedimensional π-conjugated polymeric systems have been studied. The values of x (3)(-3ω;ω,ω,ω) obtained from THG measurement for substituted PPAs increase with increasing λmax of absorption. The dispersion of x (3) (-ω;ω,0,0) for PPA film derived from Kramers-Kronig transformation of optical absorption change under the electric field (EA spectra) has been observed, and it shows the similar shape of the second derivative of the optical absorption spectra. The typical value of x (3)(-ω;ω,0,0) for o-substituted PPA was determined to be ca. 10−11 esu.

Optical nonlinearities in substituted conjugated polymers

Abstract: Conjugated polymers with sidegroups such as methyl, trimethylsilyl, p-methoxy phenyl, o-methoxy phenyl, and hexyl groups on a polyphenylacetylene chain are studied in an attempt to understand the contribution of factors such as the backbone, conformation of the chain, sidegroups and polymerization catalyst on the optical nonlinearities. The results of degenerate four-wave mixing experiments at 532 nm with nanosecond pulses indicate that the substitution of an electron-donating group away from the backbone can enhance the third-order susceptibility. Some of the polymers show optical limiting action at this wavelength. The thermal contribution to the measured susceptibility is also determined.