FIG. 7.

Linear permittivity, ${\hat{\epsilon }}^{\left(1\right)}={\epsilon }^{\left(1\right)\prime }-i{\epsilon }^{\left(1\right)\prime \prime }$ as a function of frequency, and as a function of bias electric field at 20 GHz. An interval of width $E_{\mathrm{N}\mathrm{L}}$ centered around $E_{\mathrm{d}\mathrm{c}}=0{\mathrm{V}\mathrm{m}}^{-1}$ is indicated. The error bars (gray) are the 95% confidence interval from the standard error of the mean. (a) Real part, ${\epsilon }^{\left(1\right)\prime }$. (b) Imaginary part, ${\epsilon }^{\left(1\right)\prime \prime }$.