title: Direct stress optic coefficients for YTZP ceramic and PTFE at GHz frequencies.
abstract: We report the first measurement of the direct stress optic coefficient for yttria-partially stabilized zirconia (YTZP) ceramic, using illumination between 260 and 380 GHz with applied stresses up to 27 MPa. YTZP exhibited a linear change in refractive index as a function of stress across the entire applied stress domain. A direct stress optic coefficient was also measured for polytetrafluoroethylene (PTFE). PTFE showed viscoelastic behavior at stress values above 4.5 MPa. These results open the way for quantitative sub-surface stress measurements in structural ceramics and ceramic coating systems at GHz and THz frequencies.
authors.forename: Peter
authors.initials: P
authors.lastname: Schemmel
authors.forename: Gilles
authors.initials: G
authors.lastname: Diederich
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Moore