Surface wave filters: design, construction and use

Ash, E.A.

doi:10.1016/0041-624x(80)90143-2

Cited by 5 publications

(5 citation statements)

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“…The IDTs were either fabricated with a constant wavelength of λ = 9.19 µm, or, in order to enable SAW generation over broad frequency bands [4], with a wavelength linearly varying from λ = 8.94 µm to λ = 10.38 µm along the IDT. The expected frequency responses, calculated by a simple impulse model [5,6], for these two designs are shown in Figs. S3a and The sound velocity v SAW for the given sample structure, necessary to calculate the frequency response of the IDTs, was determined by finite element modelling (FEM).…”

Section: Methodsmentioning

confidence: 99%

Supplementary document for Optomechanical wave mixing by a single quantum dot - 4883204.pdf

Weiß,

Wigger,

Nägele

et al. 2021

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Section: Methodsmentioning

confidence: 99%

Supplementary document for Optomechanical wave mixing by a single quantum dot - 4883204.pdf

Weiß,

Wigger,

Nägele

et al. 2021

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“…where W is the aperture of the IDT, ε S (∞) is the surface effective permittivity as a function of the slowness, m is an integer, s = (βp/2π)−m, P −s (− cos η) is a Legendre function and P m (cos η) is a Legendre polynomial. The definition of the coefficient S can be found in [22,29]. Owing to the constant S , the transduction coefficient in the half-space SAW is proportional to the square root of the frequency.…”

Section: Transduction Parametermentioning

confidence: 99%

Analysis of the frequency response of a dispersive IDT/ZnO/sapphire SAW filter using effective permittivity and the coupling of modes model

Chen

Wu²,

Chou

2003

J. Phys. D: Appl. Phys.

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In this paper, we propose a modified coupling of modes (COM) approach, which can be used in the practical design of a layered surface acoustic wave (SAW) filter. Unlike the half-space SAW filter, frequency dependences of the COM parameters are included by using the effective permittivity approach of surface waves. Owing to the introduction of the COM model, the effects of propagation loss, electrode reflections, electrical transduction, acoustic reception, thin film loss and the distributed finger capacitance can be taken into accounts in the frequency analysis of the layered SAW filter. The frequency response of a two-port 440 MHz IDT/ZnO/R-plane sapphire layered SAW filter is analysed and compared with the existing experimental results. Results have shown good agreement between the calculated and experimental frequency responses.

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“…Slobodnik [9] provided useful guidelines for material choice and design tradeoffs for SAW transducers in telecommunication applications many years ago. For better or worse, most of these designs devised for telecommunications [10,11] were adopted for acoustofluidics without significant change.…”

Section: Introductionmentioning

confidence: 99%

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

Zhang

Horesh

Floer

et al. 2021

J. Micromech. Microeng.

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Surface acoustic waves (SAW) have underpinned many acoustofluidic applications. But the typical straight, full-width interdigital transducers used to generate these waves are problematic. Fresnel diffraction of the propagating SAW causes strong nonuniformity in the wave's amplitude as it propagates across the substrate, leading to flow variations, recirculation, and peculiar wetting phenomena in fluids driven by such waves. These have led to many research projects and publications, but, ultimately, uniform fluid flow from SAW-driven streaming remains elusive. By adopting a form of apodization, the shaping of the IDT, we demonstrate the ability to produce laterally uniform SAW for acoustofluidics. Unlike traditional apodization, which shapes the IDT to produce a desired electrical signal, this new approach-unapodization-instead inverts the governing equations to produce a desired spatial distribution of SAW at a defined position along the propagation direction of the SAW. Theoretical analysis and experiment demonstrate a 50% improvement in the SAW uniformity over a straight IDT for three example unapodized designs, all while maintaining the same frequency, input power, quality factor, and electromechanical coupling. The sole downside is a 50% increase in IDT area to accommodate the unapodization. A design tool is provided with tabulated unapodized IDT configurations. To illustrate the potential of unapodization in acoustofluidics, the irregular dewetting and anomalous flows of a thin fluid film induced by traditional straight IDT SAW devices is shown to become regular and uniform with the adoption of unapodized SAW devices.

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Surface wave filters: design, construction and use

Cited by 5 publications

References 0 publications

Supplementary document for Optomechanical wave mixing by a single quantum dot - 4883204.pdf

Supplementary document for Optomechanical wave mixing by a single quantum dot - 4883204.pdf

Analysis of the frequency response of a dispersive IDT/ZnO/sapphire SAW filter using effective permittivity and the coupling of modes model

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

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