Cross-Linkable Zwitterionic Polyimides with High Electrooptic Coefficients at Telecommunication Wavelengths

Abstract

A series of nonlinear optical (NLO) polyimides were prepared by grafting 4-16 wt % zwitterionic pyridinium tricyanoquinonedimethane chromophore with a large negative hyperpolarizability (β 0 ) -590 × 10 -30 esu) onto the host polyimides through an ester bond formation. To enhance the temporal stability of the poled NLO polymers, a new thermally reactive group, i.e., 5-aminobenzocylcobutenone, was introduced into the NLO polymer systems to effect the cross-linking during the thermal poling process. The resulting NLO polyimides showed good solubility in polar aprotic solvents such as N,N-dimethylformamide and could form uniform films by casting or spin coating without any noticeable chromophore aggregation or phase separation as examined under an optical microscope. These NLO polyimides had glass transition temperatures in the range of 170-213 °C and were thermally stable up to 270 °C. The electrical resistivity of NLO polyimides was found to be on the order of 10 15 Ω‚cm at 80 °C and dependent on the applied voltages. As the temperature increased, the resistivity dropped monotonically to 2.4 × 10 11 Ω‚cm at 200 °C. With a 10 wt % chromophore loading (or a number density of 15 × 10 19 cm -3 ) in the polymer, the electrooptic (EO) coefficient (r 33 at 1550 nm) reached 45 pm/V. No substantial decrease in EO coefficients was observed after the test cell was kept in the dark at 85 °C under nitrogen after 1200 h nor when the test cell was irradiated with 1550 nm light (50 µW/∼4 mm 2 ) for 10 h at ambient temperature in air.

The facile synthesis and optical nonlinearity of hyperbranched polyaspartimides with azobenzene dyes

“…Thicknesses of the polymer films ranged from 1.6 to 2.3 mm, whereas refractive indices ranged from 1.57 to 1.63 (830 nm). The dye contents were determined by UV-vis investigations [56,57]. EO coefficients resulted from the in situ poling process ranged from 6.5 to 14.7 pm/ V (measured at 830 nm).…”

The synthesis and optical properties of novel fluorinated polyimides incorporated with highly electro-optic active thiazole and benzothiazole based chromophores

“…In addition the deviation of the band edges for the polymers from the operating wavelengths of the laser for telecommunication may help to decrease the absorption optical loss. According to the method described in the literature [4,33], the hetarylazo chromophores content in FPI-EHNT can be estimated. A series of NMP solutions of the chromophore EHNT with concentration in the range of 1 Â10 À5 -4 Â 10 À5 mol/L were prepared and a calibration curve was drawn from their absorption data in UVeVis spectra at about 601 nm.…”

Nonlinear optical polyimide/montmorillonite nanocomposites consisting of azobenzene dyes

“…Refraction indices range from 1.65 to 1.68. It is important to note that the dye contents were determined by UVevis spectroscopic investigations [43,44]. EO coefficients resulted from the in situ poling process are in the range between 4.6 and 8.0 pm/V (measured at 830 nm).…”