Optical anisotropy of polymeric films measured by waveguide propagation mode determination

Abstract

Extruded thin films of a liquid‐crystalline charge‐conjugated rigid‐rod polymer poly(p‐phenylenebenzobisthiazole), PBT, and a semicrystalline thermoplastic polyethylene‐terephthalate (Mylar) were fabricated and examined for film thickness, refractive index, and linear attenuation coefficient. Optical waveguide modes were successfully induced on the polymeric films using a prism coupler at λ = 633 and 1300 nm. Highly consistent thickness values were obtained for the polymeric films. In addition, the anisotropic nature of the optical properties was determined using TE and TM propagation modes. A refractive index as high as 2.3 was observed on PBT film. The refractive index data suggested that the PBT and Mylar films were optically anisotropic with refractive indices n⟂ (out‐of‐plane) invariably smaller than n∥ (in‐plane). Large anisotropy was also discovered in the linear attenuation coefficient α, with α∥/α⟂ ≈ 50 for the Mylar films. Complementary polarimetric and spectroscopic interference measurements were also applied to investigate the optical anisotropy of the extruded polymeric films. © 1992 John Wiley & Sons, Inc.

Hyperbranched Polybenzobisthiazole with High Thermal Stability, Good Organosolubility, and Interesting Optical Performance

“…Various new conjugated polymers have been designed and synthesized for efficient light emission or charge transfer 5–8. As a kind of conjugated polymer, poly( p ‐phenylene benzobisthiazole) (PBZT), is well known for its excellent mechanical properties (high tensile strength and modulus), high chemical and thermo‐oxidative resistance,9 and large and ultrafast third‐order nonlinear optics (NLO) response 10–13. However, the high degree of molecular rigidity in polymer backbones and strong intermolecular interactions give rise to the insolubility of PBZT in common organic solvents.…”

Nonlinear optical anisotropy and molecular orientational distribution in poly(p-phenylene benzobisthiazole) Langmuir–Blodgett films

“…The nonresonant linear susceptibilities XX (1) and Y Y (1) are calculated from the extraordinary and ordinary refractive indices ͑n e and n o ͒ measured at a wavelength of 632.8 nm ͑Ref. 11͒ by using the relation of n e,o 2 Ϫ1ϭ2 XX,Y Y (1) . 27 Compared to the linear susceptibilities, the NLO susceptibilities show a stronger dependence on the fabrication surface pressure.…”

Chain coherence length of rigid-rod poly(p-phenylene benzobisthiazole) and derivatives

“…The extended chain also allows delocalization of the -electrons along the polymer backbone, thus offering high potential for electrical and optical applications. [5][6][7][8] Although a simple picture of the PBZT molecule is a fully extended rod-like one, several studies 9 -12 have suggested that the molecules may possess considerable flexibility. The flexibility may arise from the out-of-plane bending of PBZT main chain, thus forming a ribbon-like chain conformation.…”