C. Samyn

High glass transition chromophore functionalised poly(maleimide-styrene)s for second-order nonlinear optical applications

Nonlinear optical polymers with high glass transition temperatures were prepared by polymer analogous reaction of maleic anhydride copolymers, with aminoalkyl-functionalised azo- and stilbene chromophores. Glass transition temperatures from 178 to 228°C were obtained. Poled films of the polymers were characterised by second-harmonic generation and showed a nonlinear optical response that is stable at elevated temperatures.

Polymer materials for second-order non-linear optical applications

Non-linear optical (NLO) polyimides and poly(maleimide-styrene)s were prepared and characterized by second-harmonic generation. Poled films of the polymers showed up to 90% of remaining NLO response at elevated temperatures; this during prolonged time at 125 °C.

High glass transition temperature chromophore functionalised poly(phenylquinoxalines) for nonlinear optics

New chromophore functionalised second-order nonlinear optical (NLO) poly(phenylquinoxalines) were prepared by reaction of a bis(1,2-dicarbonyl)chromophore monomer and a tetraamine at room temperature. The heterocyclic polymers have high glass transition temperatures (>195 °C) and can therefore be excellent polymeric materials with high poling stabilities of the NLO effect.

FT-IR spectrometric study of N-t-butoxycarbonylglycine N′,N′-dimethylamide and its interaction with proton donors

FT-IR spectra of N-t-butoxycarbonylglycine-N′,N′-dimethylamide and its deuteriated ND counterpart, in solution and in the solid state, have been analysed between 3800 and 400 cm–1. An assignment is proposed for some important vibrations, especially for the so-called amide vibrations, by comparison with literature data on similar molecules. The frequency shifts and intensity changes of the vibrations sensitive to the physical state of this model dipeptide strongly suggest that intermolecular hydrogen bonds involving mainly the NH and CO (amide) groups are formed in the solid state. Thermodynamic parameters (equilibrium constants and enthalpies) of the hydrogen-bond formation with phenol derivatives have been determined in carbon tetrachloride and in 1,2-dichloroethane. The complexes investigated are of medium strength. The FT-IR spectra in the νCO region and the double perturbation of the νNH band assigned to the five-membered intramolecular NH ⋯ OC hydrogen-bonded ring clearly show that complex formation occurs at both the amide and urethane carbonyl groups. About 45% of the complexes are formed on the CO (urethane) function, almost independent of the acidity of the phenols. The unusual broadness of the OH ⋯ OC complex band originates from the superposition of two complex bands. N-t-Butoxycarbonylglycine-N′,N′-dimethylamide can be considered as being built up from two model molecules, methyl-N-methylcarbamate and N,N-dimethylacetamide.

Synthesis of frequency doubling nonlinear optical polymers, functionalized with aminonitro-stilbene dyes. Second harmonic generation in corona poled thin films

Abstract The synthesis and second harmonic coefficients, d 33 , and d 31 as well as the related susceptibilities, χ (2) zzz , of two new series of (NLO-dye methacrylate)-(methyl methacrylate) copolymers were investigated. The NLO-chromophores bound covalently to the polymer chain were 4-nitro-4′-dialkylamino-α-cyano-stilbene, 4-nitro-4′-dialkylamino-stilbene. Thin films were obtained by spin-coating and poled by a positive corona discharge using a needle electrode in order to induce noncentrosymmetry into the systems. Nonlinear susceptibilities, χ (2) zzz , of the films were derived from the analysis of full-angle Maker fringe patterns at 1064 nm. χ (2) zzz values as high as 3.2 · 10 −7 esu could be measured.

Polymers containing nonlinear optical groups in the main chain. Second harmonic generation in corona poled thin films

Abstract Linear polyesters with azobenzene and stilbene chromophores were synthesized and examined for their frequency doubling effect by second harmonic generation measurements. The incorporation of long flexible units results in copolyesters which are soluble in common organic solvents but which show a decrease in Tg; nonlinear optical efficiency χ(2) values as high as 2.6 · 10−9 esu were obtained.

Synthesis of frequency doubling nonlinear optical polymers, functionalized with aminocyano- and alkoxycyano-stilbene dyes. Second harmonic generation in corona poled thin films

Abstract New NLO dye methacrylate-methylmethacrylate copolymers were synthesized. The NLO-chromophores bound covalently to the polymer chain are: 4-cyano-4′-dialkylamino-α-cyano-stilbene, 4-cyano-4′-alkoxy-α-cyano-stilbene and 4-cyano-4′-alkoxy-stilbene. Films spincoated from these polymers were poled by a positive corona discharge just above T g (as measured by DSC). Nonlinear susceptibilities [X zzz (2) of the films were derived from the analysis of full-angle Maker fringe patterns at 1064 nm] X zzz (2) values as high as 1.43 · 10 −7 e.s.u. could be achieved.

Polymers for second-order nonlinear optical applications

The aim of our investigation is the development of new polymeric materials with nonlinear optical properties which are comparable or even better than the existing organic salts such as LiNbO/sub 3/, KDP etc. Nonlinear optical (NLO) polymers which show large second-order NLO properties and which show long-term stability, low optical loss and good processibility to fabricate thin films and fibers are of considerable interest in the development of new materials used for frequency doubling applications and for their use in optical communication.

Second Order Hyperpolarisabilities and Conformations of Functionalised Copolymers

SHG in LB-deposited monolayers of NLO-functionalised poly-MMA on glass was studied. These organic thin films show efficient SH-generation in spite of the decrease in chromophore hyperpolarisability which may be attributed to dipolar interactions. These adverse effects are counteracted by the favorable orientation of the NLO-chromophores in the polymer.