Tham khảo tài liệu 'ferroelectrics material aspects part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Strontium Barium Niobate Thin Films for Dielectric and Electro-Optic Applications 515 0 20 40 60 80 Angle of incidence 0 deg Fig. 18. Electric-field induced response for TM polarization ARtm . The three electro-optic eo converse-piezoelectric CPE and electro-absorptive EA contributions are detailed in a and comparison with experimental response is given in b . Amplitude of modulated voltage applied to SBN film is 1V. Extraordinary refractive index ne is the single adjustable parameter of characterization procedure two cases are shown ne no top and ne no - bottom . The latter corresponds to the best calculation-experiment fit. The electro-optic coefficient r33 determined from characterization procedure and used for ARtm calculation is equal to top and pm V bottom . coefficients r13 r33 d33 of the film appear reduced in similar proportions by a factor about 5 1. The magnitude of polarization in our SBN films is also measured about 5 times lower than that reported for SBN 60 single domain crystals. As already mentioned above a correlation between these results is not surprising. Although lower than those of SBN crystals the application relevant e-o coefficients measured on SBN 60 thin films r33 pm V reff r33 - no ne 3 r13 pm V are larger than those of a crystal of lithium niobate at the same wavelength x 633 nm r33 pm V reff pm V . A further improvement of these SBN film coefficients is expected from the understanding of a lower polarization in films and from an increase in Sr content. The SBN thin film path is therefore proved to be competitive with regard to e-o modulation. Beside the e-o coefficient the refractive index and the dielectric permittivity of 516 Ferroelectrics - Material Aspects the material are also involved in the e-o performance. The low dielectric permittivity of lithium niobate is an advantage to be taken into account when comparing thin film paths. 6. Conclusion An overview of the questions relative to the .
