Fig. 5: Frequency dependence of the Pockels shift in a device.
a, Schematic of a hypothetical device with a potential difference V across two electrodes separated by a width w; a cladding material (grey) with permittivity εC, susceptibility \({\chi }_{{\rm{C}}}^{\left(1\right)}\) and width wC; and an EO material (green) with permittivity εBTO, susceptibility \({\chi }_{{\rm{BTO}}}^{\left(1\right)}\) and width wBTO. The blue line marks how the boundary condition at the bottom of the diagram affects the electric-field strength in each material assuming εBTO > εC. b, Refractive-index change in the BTO material according to equation (6) as a function of frequency for varying ratios Rw with εC = 4. The measured permittivity of BTO in this work (Table 1) was used as the input for εBTO and is plotted in green. Δn is normalized to its low-frequency value at 100 MHz to highlight the frequency dependence for each case.
