Fig. 2: Electro-optomechanical phase modulation.
From: Electrically interfaced Brillouin-active waveguide for microwave photonic measurements
a The experimental setup for electrical characterization. VNA: vector network analyzer. b A heterodyne setup to characterize electro-optomechanical phase modulation. SG: signal generator, AOM: acousto-optic modulator, RFSA: RF spectrum analyzer. Microwave reflection ∣S11∣ (c) and transmission ∣S21∣ (d) of the IDTs, obtained from experimental measurements (blue) and finite-element simulations (grey). These traces reveal two distinct electromechanical resonances corresponding to modes A and B, with detailed mode profiles shown as insets in (d). e The first optical sideband measurement by sweeping the driving RF frequency obtained using the setup shown in (b). The scattering efficiency, defined as the conversion efficiency of the 1st sideband ∣a1∣2/∣a0∣2, is proportional to the mode overlaps between the acoustic ((d) inset) and optical ((e) inset) modes. As a result, mode A exhibits significantly stronger modulation efficiency compared to mode B. f RF power sweep of scattering efficiency of first three sidebands at mode A, which closely follows the theoretical predictions of Bessel functions. We obtain a Vπ = 8.13 V and VπL = 0.13 V cm. g Scattering of the first sideband shows minimal variation over a wavelength range of 100 nm. The measurement is taken under the RF drive of 8.92 dBm.
