Fig. 2: Optomechanical coupling strengths for varying cavity-drum geometries.

In a the calculated G⁽¹⁾(t_drum, h_drum) are shown as a color-map, with {t_drum, h_drum} normalized to the respective material wavelength. Measured g₀ for two exemplary polymer drums are highlighted in green (drum 1) and purple (drum 2) and plotted along the third plot-axis. By scanning the probe-wavelength, the measurements of the two drums trace out cuts in the map. Four cavity geometries corresponding to special coupling scenarios are highlighted: triangle and square correspond to G⁽¹⁾ = 0, diamond and circle maximize ∣G⁽¹⁾∣. In b (bottom) a sketch of the cavity intensity I_cav of an exemplary cavity geometry is shown. The cavity intensity at the two polymer-air/vacuum interfaces is shown for the four scenarios from a (triangle, square, diamond, circle). In c the measured g₀ from image a are plotted against the scanned probe laser wavelength λ for both drum 1 (green) and drum 2 (purple). The error bars represent the combined fit and measurement uncertainty.