Figure 5
(a) The extracted oscillations of the reflectivity change of different parts of the tube (of sample Br) with a number of windings from 1 to 5 (from top to bottom) are presented. (b) The corresponding FFTs. The transition from the frequencies of a single oscillating bilayer towards modes of a multilayer is visible. In the FFT additionally to the experimental results also the calculations of the modes (vertical lines) based on a transfer matrix method with a massless spring in between the layers are presented. The green arrows mark the remaining acoustic contributions for the 4 and 5 windings sample for better visibility.
