Fig. 3. Design and characterization of BOIMUX.

All presented transmissions are normalized. (A) ER map. ER ≤ 6 dB is required to secure nonzero optical transmission. (B) V_switch map. Small V_switch is required for high sensitivity to record the 20-V small E_control. (C) CMRR design with push-pull electrode layout. Waveguides are sandwiched by the top and bottom electrodes (inset: TEM). The top electrode of MRR1 is connected to the bottom electrode of MRR2 and vice versa (inset: SEM). This design helps double the voltage sensing range without sacrificing sensitivity. (D) DC response of BOIMUX showing good linearity of resonant wavelength change with respect to applied voltages. a.u., arbitrary units. (E) Comparison of transmission-voltage curve in single MRR and BOIMUX. For a single MRR, only one trough is presented. The sensitive range is from −25 to 95 V. For BOIMUX, two troughs can be observed when the operation wavelength λ_op (1551.5056 or 1551.5256 nm) does not coincide with λ_mid (1551.4756 nm). The sensitive range is extended to cover −80 to 165 V at λ_op = 1551.5056 nm. (F) AC response of BOIMUX under different applied voltages. The working wavelength is 1551.5056 nm. (G) Zoom in of (F) for analyzing AC response in submicrosecond scale.