Journal of the Optical Society of America B · 1991 · 81 citations · 10 references
Natural SciencesMaterials EngineeringMaterials ScienceOptical MaterialsOpticsPolymer ChemistryElectro-optic EffectsNonlinear Optical MaterialsNonlinear OpticsOptical PolymersPolymer Thin FilmsRefractive IndexElectro-optic CoefficientsElectro-optic PolymersNonlinear Optical PolymersNonlinear Optical PropertiesNonlinear Refractive IndexNonlinear WaveguidesPolymer WaveguidesWaveguide Modes
The study introduces a restriction parameter ν to develop a simple model that explains electro‑optic coefficient ratios between 3 and 6. Planar waveguides were fabricated from a bisphenol‑A epoxy copolymer, and the refractive indices and electro‑optic coefficients (r33, r13) were measured via waveguide mode analysis at 632.8 nm for both electrode and corona poling, with restricted chromophore motion during poling proposed to explain the observed coefficient ratios, leading to a simple model incorporating ν. The measured electro‑optic coefficient ratio r33/r13 exceeded the theoretical value of 3, indicating second‑order susceptibilities higher than expected.
Planar waveguides were made from a linear epoxy copolymer of bisphenol-A diglycidyl ether and amino-nitro-tolane. The refractive indices, nTM and nTE, and the electro-optic coefficients, r33 and r13, of the poled nonlinear-optical 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 ν (0 ≤ ν ≤ 1), we develop a simple model that can account for electro-optic coefficient ratios ranging from 3 to 6.
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