Relative electrical resistivities and poling of nonlinear optical polymeric waveguides (original) (raw)
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Macromolecules, 1994
Rotational dynamics of nonlinear optical chromophores embedded in amorphous polymer films were studied using second harmonic generation. Corona poling was used to orient the chromophores into the bulk noncentrosymmetric structure required to observe second-order nonlinearity. Electric field effects were examined by simultaneously measuring the second harmonic signal (during and following poling) and surface voltage decay (following poling). It is found that for short times the residual field following poling retards chromophore reorientation. A mathematical model that describes the rotational Brownian motion of chromophores in a polymer matrix is developed to simulate the field-dependent behavior. The electric field effects can therefore be deconvoluted from the Brownian motion to reveal information concerning local mobility in polymers. Further applications of the model in distinguishing the post-poling electric field effects and in computing the local free volume and viscosity are discussed. A first attempt is made to realize the contributions of the residual surface voltage, field-induced bulk charges, and thermally injected charges to the rotational motion of the chromophores. The magnitude of the local free volume and the local viscositytemperature behavior in a doped poly(methy1 methacrylate) system are estimated and compared with those predicted by the Doolittle-Williams-Landel-Ferry equation.
Synthesis and characterization of polymers for nonlinear optical applications
2003
A difunctional NLO Azo-Dye chromophore has been synthesized and polymerization has been performed with a comonomer bearing a side-chain epoxy group. Deposition of the polymer on glass substrates was performed by spin-coating, resulting in uniform films up to 2 μm thickness. The orientation of the chromophore was performed under a "pin-to-plane" positive corona discharge followed by a heat- treatment in order to obtain reticulation of the films. Molecular orientation has been investigated using UV-Vis. and Raman spectroscopy. Poling of the films results in a decay of absorbance as well as in a blue shift of the spectrum. At the same time, the 1600 cm-1 band disappears from the Raman spectra, indicating orientation of the chromophores. Cross-linking has been studied by FTIR and all-optical poling and showed an improved stability of the electro-optic thin films.
Study of the optical nonlinearity of polymeric films containing organic materials
Journal of Optical Technology, 2001
This paper analyzes two widely used experimental methods of diagnosing the nonlinear photoresponse of polymeric films containing organic materials: a method based on scanning the sample close to the focal plane of a lens, and a method of phase-modulated beams, based on the self-diffraction of coherent beams in the bulk of the test medium. These methods are used to measure the photoinduced refractive-index change of thick ͑about 40 m͒ polymeric films and thin ͑about 0.5 m͒ Langmuir-Blodgett films containing bacteriorhodopsin. It is shown that the photoresponse-saturation effect of the medium needs to be taken into account in order to interpret the experimental results obtained by the two methods.
Electro-optic coefficients in electric-field-poled polymer waveguides
Journal of the Optical Society of America B, 1991
Planar waveguides were made from a linear epoxy copolymer of bisphenol-A diglycidyl ether and amino-nitrotolane. The refractive indices, nTM and nTE, and the electro-optic coefficients, r 33 and r 1 3, of the poled nonlinearoptical polymer films were determined by measurements of the waveguide modes of these films at a wavelength of 632.8 nm, and the results are reported for both electrode and corona poling. The ratio of the second-order susceptibilities was found to exceed significantly the theoretically expected value of 3. The restricted motion of the nonlinear chromophores during poling provides a possible explanation of this discrepancy. Introducing a restriction parameter v (0 < v c 1), we develop a simple model that can account for electro-optic coefficient ratios ranging from 3 to 6.
Estimation of electrostriction coefficients of a nonlinear optical polymer electret
Russian Chemical Bulletin, 2008
The effect of organic chromophores incorporated into a polymer electret and responsible for its nonlinear optical (NLO) response to an applied electric field on the electrostriction coefficients (ESC) of the material is studied. Analytical expressions for the ESC were derived in the framework of a model proposed earlier, which includes the effect of a locally anisotropic, polarizable and deformable environment on the electric characteristics of the chromophore. The dependence of the ESC on both macroscopic and microscopic parameters of the molecular system is established. Numerical estimates of the ESC for poly(methyl methacrylate) doped with the dye Disperse Red 1 and dimethylaminonitrostilbene doped polycarbonate agree with experimental data in order of magnitude. The relations obtained can be used in the design of novel organic NLO materials.