Showing papers by "Alex K.-Y. Jen published in 1995"

Highly active and thermally stable nonlinear optical polymers for electro-optical applications

Abstract: Poled guest-host polyquinoline thin films are shown to demonstrate both exceptionally large electro-optic activity and long-term thermal stability. After an initial drop from 45 pm/V to 26 pm/V in the first 100 hours, the electro-optic coefficient r33 at 26 pm/V remained for more than 2000 hours.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Hyper‐Rayleigh scattering studies of first order hyperpolarizability of tricyanovinylthiophene derivatives in solution

Abstract: First order hyperpolarizabilities, β, for donor–acceptor substituted heteroaromatic compounds are measured by the hyper‐Rayleigh scattering technique. Hyper‐Rayleigh scattering utilizes the mechanism of number density fluctuations and enables the second harmonic generation signal of nonlinear optical chromophores to be generated as scattered light. Effects of substituting different electron donating groups to the parent heteroaromatic compounds and different solvents on the hyperpolarizability is investigated using this technique.

The use of sodium salts as nucleation agents for polyethylene terephthalate with minimal molecular weight reduction

Abstract: The sodium salts of carboxylic acids and other weak acids are routinely used as nucleation agents for injection moldable poly(ethylene terephthalate) (PET) resins. One of the primary drawbacks accompanying their use is the degradation of the PET resulting from the attack of the ester by the sodium carboxylate. Several sodium carboxylates have been found based on pyrrole carboxylic acid that are effective as nucleants but which do not cause a reduction in the molecular weight of PET. In addition, tetraphenyl borate salts, although only marginally effective as nucleants, were observed to be efficient additives to PET for counteracting molecular weight loss caused by chemical nucleants.

Experimental studies of the second-order nonlinear optical response of a novel class of tricyanovinylated thiophene compounds

Abstract: We measured the second-order nonlinear optical response of a novel class of tricyanovinylated thiophene compounds using electric-field-induced second-harmonic generation. Very large second-order nonlinearity was observed for these compounds. The results indicate that the combination of the tricyanovinyl acceptor and the thiophene conjugating moiety offers excellent molecular second-order optical nonlinearity.

Highly Active and Thermally Stable Ctlromophores and Polymers for Electro-Optic Applications

Abstract: We have developed two new classes of highly active and thermally stable nonlinear optical (NLO) chromophores based on the use of efficient thiophene conjugating units, a N,N-diphenylamino electron-donating group, and a 1,1′-dicyanovinyl substituted electron-accepting group. We have also developed a facile and generally applicable method to functionalize NLO chromophores onto high temperature polymers to demonstrate both high electro-optic (E-O) coefficients and long-term alignment stability at 100 °C.

New developments in thermally stable second order nonlinear optical chromophores and electro-optic polymers

Abstract: A new class of thermally and chemically stable donor-acceptor substituted thiophenes is presented. It is shown that exceptionally large electro-optic activity (as high as 30 pm/V at 1.3 micrometers ) can be achieved by doping/covalently bonding highly efficient trycyanovinylthiophenes into high temperature polymers such as polymidies and polyquinolines. Monitoring the long-term stability of electro-optic activity at temperatures above 100 degrees C has revealed that the covalent bonding approach is quite superior to the guest-host approach in polymide as well as polyquinoline based materials.

New Developments in Thermally and Chemically Stable Nonlinear Optical Chromophores for E-O Device Applications

Abstract: A new class of second order nonlinear optical chromophores resulted from the replacement of the most reactive CN group in tricyanovinylthiophene derivatives with aryl units, have been designed and synthesized. It was shown that these chromophores provide excellent tradeoffs among many relevant properties such as molecular nonlinearity, linear absorption at 830 nm, inherent thermal stability, chemical stability in processing solvents as well as host polymer matrices at high temperatures and attenuation at 830 nm.