ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The in-plane optical loss was correlated with molecular orientation in a unidirectionally stretched poly(ethylene terephthalate-co-isophthalate) copolyester film. X-ray scattering was applied to ascertain the anisotropic and amorphous natures of the stretched film. The film was adhered onto a silicon wafer to fabricate a planar waveguide. Multiple TE and TM propagation modes were obtained on the planar waveguide using a prism coupler at 632.8 nm yielding in-plane refractive indices of 1.6545 and 1.5464, parallel and transverse to the stretch direction, respectively. For each waveguide mode, a propagation streak was generated and registered on photographic film. The in-plane linear attenuation coefficient, α(parallel)≡{ln[I(O)/I(x(parallel))]}/x(parallel), was derived from the propagation streak. The optical path of each mode was determined and used to normalize α(parallel). For the TE modes, α(parallel) increased with the mode number and was highly anisotropic, i.e., α(parallel) (parallel to the stretch direction)≤α(parallel) (transverse to the stretch direction). However, for the TM modes, α(parallel) was found to be a constant smaller than those of the TE modes, and was independent of mode number as well as molecular orientation. The bulk α(parallel) was extrapolated to remove the surface loss contributions for the planar waveguide. Dipole interaction between the stretched copolyester, surface irregularities, and the TE or TM polarization was analyzed to delineate the in-plane optical loss behavior. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.362609
