Figure 8: SiC microdisk laser interferometric system and calibration of motion transduction/laser heating.

(a) Schematic illustrating the multiple reflections of laser beams from all the relevant interfaces. The uniformity of the SiC thickness and vacuum gap ensures a uniform ‘dc’ background or off-resonance baseline throughout the device area, which is key to spatially mapping the multimode motions. (b) Calculated reflectance versus vacuum gap depth. Flexural-mode thermomechanical motion leads to minuscule vertical displacement of SiC microdisk and thus slightly changes the depth of vacuum gap. The slope of the curve at the fabricated gap depth determines the responsivity. (c) Measured reflectance map (in colour scale) of a representative device (its resonance data are shown in Fig. 4 of the main text), demonstrating uniformity in the measured ‘dc’ and off-resonance background. Dashed circles outline the edges of the disk and the pedestal.