Electric field sensors using nonlinear optical polymers

Abstract

This work is part of a continuing project that is investigating the use of integrated optical (IO) waveguides and optical fibers coated with nonlinear optical (NLO) polymers as electric field sensing devices. The IO waveguides were fabricated using three different techniques: (1) in the NLO polymer itself (on glass and silicon substrates), (2) in glass microscope slides using thin film silver diffusion and silver ion exchange methods, and (3) in thin film optical epoxies. The Ag+ glass and UV cured optical epoxy waveguides were subsequently coated with NLO polymers; the 3-D patterned waveguides provided lateral confinement of the optical wave that propagated in the polymer. A low index buffer layer of polysiloxane glass resin (Owens Illinois GR650E) was needed on the silicon substrates to decrease the propagation loss. The NLO polymers were dip coated or spun on these substrates and were poled with a corona poling technique with fields of the order of 3 MV/cm. Interferometric and polarization rotation methods were used to measure the effects of applied electric fields on the NLO devices at wavelengths of 633, 780, and 830 nm. Electrooptic coefficients were determined and compared with similar coefficients obtained using second harmonic generation methods on the same NLO polymers.