Resonance and beating phenomenon in a nonlinear rigid cylindrical acoustic waveguide: The axisymmetric mode

Detailed spatial-spectral numerical characterization of axially symmetric broadband ultrasonic resonances in standard optical fibers

“…(f) Resonances: in summary, all the propagating modes interact inside the fiber inducing a large strain field at the resonance frequencies. Closer modal wavenumbers increase the beat amplitude and period as resonance is approached [54]. The largest beatlength values are graphically observed as peaks in the FFT spectra in Fig.…”

“…Wavenumbers k of two acoustic modes propagating in the fiber converge to close values at the resonances of f = 29 and 68 MHz (Fig. 3 (d) Beatlengths: constructive and destructive interference is caused by the phase velocity difference between the different modes inducing beating effects [54]. The beatlength is the spatial measure or period between two maxima or minima of the modal interference.…”