Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHigh-acoustic-index-contrast phononic circuits: numerical modeling
236
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We numerically model key building blocks of a phononic integrated circuit that enable phonon routing in high-acoustic-index waveguides. Our particular focus is on Gallium Nitride-on-sapphire phononic platform which has recently demonstrated high acoustic confinement in its top layer without the use of suspended structures. We start with systematic simulation of various transverse phonon modes supported in strip waveguides and ring resonators with sub-wavelength cross-section. Mode confinement and quality factors of phonon modes are numerically investigated with respect to geometric parameters. Quality factor up to $10^{8}$ is predicted in optimized ring resonators. We next study the design of the phononic directional couplers, and present key design parameters for achieving strong evanescent couplings between modes propagating in parallel waveguides. Last, interdigitated transducer electrodes are included in the simulation for direct excitation of a ring resonator and critical coupling between microwave input and phononic dissipation. Our work provides comprehensive numerical characterization of phonon modes and functional phononic components in high-acoustic-index phononic circuits, which supplements previous theories and contributes to the emerging field of phononic integrated circuits.
rate research
Read More
We investigate the prospects for micron-scale acoustic wave components and circuits on chip in solid planar structures that do not require suspension. We leverage evanescent guiding of acoustic waves by high slowness contrast materials readily available in silicon complementary metal-oxide semiconductor (CMOS) processes. High slowness contrast provides strong confinement of GHz frequency acoustic fields in micron-scale structures. We address the fundamental implications of intrinsic material and radiation losses on operating frequency, bandwidth, device size and as a result practicality of multi-element microphononic circuits based on solid embedded waveguides. We show that a family of acoustic components based on evanescently guided acoustic waves, including waveguide bends, evanescent couplers, Y-splitters, and acoustic-wave microring resonators, can be realized in compact, micron-scale structures, and provide basic scaling and performance arguments for these components based on material properties and simulations. We further find that wave propagation losses are expected to permit high quality factor (Q), narrowband resonators and propagation lengths allowing delay lines and the coupling or cascading of multiple components to form functional circuits, of potential utility in guided acoustic signal processing on chip. We also address and simulate bends and radiation loss, providing insight into routing and resonators. Such circuits could be monolithically integrated with electronic and photonic circuits on a single chip with expanded capabilities.
The recent breakthrough in metamaterial-based optical computing devices [Science 343, 160 (2014)] has inspired a quest for similar systems in acoustics, performing mathematical operations on sound waves. So far, acoustic analog computing has been demonstrated using thin planar metamaterials, carrying out the operator of choice in Fourier domain. These so-called filtering metasurfaces, however, are always accompanied with additional Fourier transform sub-blocks, enlarging the computing system and preventing its applicability in miniaturized architectures. Here, employing a simple high-index acoustic slab waveguide, we demonstrate a highly compact and potentially integrable acoustic computing system. The system directly performs mathematical operation in spatial domain and is therefore free of any Fourier bulk lens. Such compact computing system is highly promising for various applications including high throughput image processing, ultrafast equation solving, and real time signal processing.
High index optical waveguide devices such as slab waveguides, strip waveguides and fibers play extremely important roles in a wide range of modern applications including telecommunications, sensing, lasing, interferometry, and resonant amplification. Yet, transposing these advantageous applications from optics to acoustics remains a fundamental practical challenge, since most materials exhibit refractive indices lower than that of air for sound waves. Here, we demonstrate the relevance of acoustic metamaterials for tackling this pivotal problem. More specifically, we consider a metamaterial built from subwavelength air-filled acoustic pipes engineered to effectively exhibit a higher refractive index than homogenous air. We show that such medium can be employed to realize acoustic equivalents of dielectric slab or strip waveguides, and optical fibers. Unlike conventional acoustic pipes, our guiding approach allows the waveguide to remain open to the external medium, which opens a plethora of new opportunities in noise management, medical imaging, underwater communication systems, and sensing.
The rising need for hybrid physical platforms has triggered a renewed interest for the development of agile radio-frequency phononic circuits with complex functionalities. The combination of travelling waves with resonant mechanical elements appears as an appealing means of harnessing elastic vibration. In this work, we demonstrate that this combination can be further enriched by the occurrence of elastic non-linearities induced travelling surface acoustic waves (SAW) interacting with a pair of otherwise linear micron-scale mechanical resonators. Reducing the resonator gap distance and increasing the SAW amplitude results in a frequency softening of the resonator pair response that lies outside the usual picture of geometrical Duffing non-linearities. The dynamics of the SAW excitation scheme allows further control of the resonator motion, notably leading to circular polarization states. These results paves the way towards versatile high-frequency phononic-MEMS/NEMS circuits fitting both classical and quantum technologies.
We report direct visualization of gigahertz-frequency Lamb waves propagation in aluminum nitride phononic circuits by transmission-mode microwave impedance microscopy (TMIM). Consistent with the finite-element modeling, the acoustic eigenmodes in both a horn-shaped coupler and a sub-wavelength waveguide are revealed in the TMIM images. Using fast Fourier transform filtering, we quantitatively analyze the acoustic loss of individual Lamb modes along the waveguide and the power coupling coefficient between the waveguide and the parabolic couplers. Our work provides insightful information on the propagation, mode conversion, and attenuation of acoustic waves in piezoelectric nanostructures, which is highly desirable for designing and optimizing phononic devices for microwave signal processing and quantum information transduction.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
