Figure 1
From: Broadband reconfigurable logic gates in phonon waveguides
An electromechanical phonon waveguide. (a) A schematic of the FWM-like process in the electromechanical phonon WG. The individual membranes (light blue) in the WG are suspended above the substrate and isolated from their surroundings (grey) thus enabling acoustic phonon vibrations to be confined and guided. The left inset shows a false-colored electron microscope image of the device indicating the WG width (w) and the hole pitch (a). The right insets show energy diagrams for the FWM-like process, investigated in this report, and TWM process previously employed to execute mechanical logic circuits. In this process, a strong pump wave (red arrow) activates a third-order term in the restoring force in the phonon WG and the simultaneous excitation of a signal wave (blue arrow) stimulates the emission of a new idler wave (green arrow). (b) The phonon transmission spectrum in WG 1 when excited from the left edge with 1 Vrms and measured at the right edge via optical interferometry in a vector signal analyser. The phonon band is divided into four 1-MHz spectral regions, labelled G1, G2, G3 and G4 and highlighted in red, yellow, green and blue respectively, in order to demonstrate frequency-division-multiplexed logic gates detailed below.
