Acoustic, Phononic, Brillouin Light Scattering and Faraday Wave Based Frequency Combs: Physical Foundations and Applications

Abstract

Frequency combs (FCs)—spectra containing equidistant coherent peaks—have enabled researchers and engineers to measure the frequencies of complex signals with high precision thereby revolutionising the areas of sensing, metrology and communications and also benefiting the fundamental science. Although mostly optical FCs have found widespread applications thus far, in general FCs can be generated using waves other than light. Here, we review and summarise recent achievements in the emergent field of acoustic frequency combs (AFCs) including phononic FCs and relevant acousto-optical, Brillouin light scattering and Faraday wave-based techniques that have enabled the development of phonon lasers, quantum computers and advanced vibration sensors. In particular, our discussion is centred around potential applications of AFCs in precision measurements in various physical, chemical and biological systems in conditions, where using light, and hence optical FCs, faces technical and fundamental limitations, which is, for example, the case in underwater distance measurements and biomedical imaging applications. This review article will also be of interest to readers seeking a discussion of specific theoretical aspects of different classes of AFCs. To that end, we support the mainstream discussion by the results of our original analysis and numerical simulations that can be used to design the spectra of AFCs generated using oscillations of gas bubbles in liquids, vibrations of liquid drops and plasmonic enhancement of Brillouin light scattering in metal nanostructures. We also discuss the application of non-toxic room-temperature liquid-metal alloys in the field of AFC generation.

Gas Bubble Photonics: Manipulating Sonoluminescence Light with Fluorescent and Plasmonic Nanoparticles

“…It is also plausible that the use of more than two excitation frequencies or even a quasi-continuum of frequencies would result in strong sonoluminescence provided that the bubble maintains its spherical shape during the oscillation. One potential test of this idea could employ acoustic frequency combs-signals with spectra consisting of equidistant frequency peaks [29]. Despite a multifrequency content of an acoustic frequency comb signal, a bubble driven by it can still maintain its spherical shape [108] that is favourable for producing sonoluminescence [35].…”

“…Apart from their applications in biomedicine, bubbles have also been used for texture tailoring in food industry [20], natural gas recovery in petroleum industry [21], material synthesis in material sciences [22], lab-on-a-chip devices [23], wastewater treatment systems [24], sonochemistry (enhancement and alternation of chemical reactions by means of ultrasound) [25,26], sonoprocessing [25,27] and underwater acoustic communication [28,29]. Moreover, it has been hypothesised that acoustic and fluid-mechanical properties of bubbles in the primordial ocean might contribute to the origin of life on Earth [30] and that the presence of bubbles in the brain and their collapse might be associated with blast-induced neurotraumas [31,32].…”

Biomechanical Sensing using Gas Bubbles Oscillations in Liquids and Adjacent Technologies: Theory and Practical Applications

“…Since viscous forces acting in the fluid near the wall are neglected, one can use the potential flow theory to replace the wall with an identical 'mirror' bubble image that is located symmetrically with respect to the rigid wall and oscillates with the same frequency, amplitude, and phase as the original bubble [71,83]. Even though in reality, Bjerknes forces could cause the distance s 2 between the bubble centre and the wall vary [67,[85][86][87] (also see Sec. 2.3), for simplicity one often assumes that it remains constant (Fig.…”

“…For a review of the recent developments in the emergent field of acoustic frequency 581 combs (AFCs) readers are referred to [87]. Here, we first describe an important class of 582 AFCs-AFCs based on the oscillations of acoustically-driven gas bubbles in liquids-and 583 then discuss their potential applications in the field of biosensing.…”

“…was comprehensively addressed (see also [87]). In [86], polydisperse clusters consisting 660 of mm-sized bubbles with equilibrium radii R n0 = R 10 /n were used, where R 10 is the equilibrium radius of the largest bubble in the cluster and n = 1, 2, 3, .…”