pith. sign in

arxiv: 2511.18795 · v1 · submitted 2025-11-24 · ❄️ cond-mat.mes-hall

Impedance-matched High-Overtone Thickness-Shear Bulk Acoustic Resonators with Scalable Mode Volume

Zi-Dong Zhang , Zhen-hui Qin , Yi-Han He , Yun-Fei Cheng , Hao Yan , Si-Yuan Yu , Ming-Hui Lu , Yan-Feng Chen This is my paper

Pith reviewed 2026-05-17 06:08 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall
keywords high-overtone bulk acoustic resonatorthickness shear modelithium niobateimpedance matchingquantum interconnectsspurious mode suppressionhigh quality factormicrowave photonics
0
0 comments X

The pith

A laterally excited high-overtone thickness-shear resonator removes parasitic losses to reach over 99 percent energy transfer efficiency with tunable mode volumes.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper presents the X HTBAR, a new design for high-overtone bulk acoustic resonators that uses lateral electrodes on a thin lithium niobate film to excite thickness shear modes. This planar approach confines the acoustic energy between the top electrodes without requiring a bottom electrode, thereby eliminating parasitic loss channels. As a result, the device attains energy transfer efficiency greater than 99 percent, a stable free spectral range of approximately 5.75 MHz, and frequency-quality products exceeding 10^13 at room temperature. The design also allows tunable mode volumes through gridded electrodes and suppresses spurious modes due to the properties of the 128 degree Y-cut LiNbO3 material. These advances position the resonators as promising sources for multimode phonons in quantum interconnects and microwave photonic circuits.

Core claim

The X HTBAR employs a 3 micron thick 128 degree Y cut LiNbO3 piezoelectric film on a 500 micron high resistivity silicon substrate with lateral electrodes to excite and confine thickness shear modes. This configuration removes parasitic loss channels and achieves energy transfer efficiency greater than 99 percent while providing a stable free spectral range of about 5.75 MHz with small fluctuations. Experimental results include comb-like phonon spectra from 0.1 to 1.8 GHz, high quality factors, frequency-quality products larger than 10^13 at room temperature, and tunable mode volumes from 0.008 to 0.064 cubic millimeters using gridded electrodes that also suppress spurious modes.

What carries the argument

The laterally excited high-overtone thickness-shear bulk acoustic resonator (X HTBAR), which uses top lateral electrodes to excite and confine acoustic fields in a piezoelectric thin film on a substrate.

If this is right

  • The fully planar structure simplifies integration into microwave photonic integrated circuits and quantum devices.
  • Stable free spectral range and high frequency-quality products support precise multimode phonon sources for quantum interconnects.
  • Gridded electrode designs combined with the piezoelectric material properties suppress spurious modes across the operating band.
  • Tunable mode volumes from 0.008 to 0.064 cubic millimeters enable optimization for different scales of quantum or signal-processing applications.
  • Low temperature coefficient of frequency improves long-term stability in room-temperature and cryogenic environments.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Eliminating the bottom electrode may reduce fabrication steps and mechanical stress when building large arrays of these resonators.
  • The reported efficiency could translate to lower power dissipation and reduced heating in quantum acoustic circuits.
  • Scalable mode volumes suggest a path toward adjustable phonon capacity in hybrid quantum systems.
  • The approach might extend to other piezoelectric cuts or substrates to target different frequency bands without redesigning electrode geometry.

Load-bearing premise

Lateral excitation through top electrodes alone fully confines the acoustic field and eliminates all parasitic loss channels without introducing new damping mechanisms.

What would settle it

A measurement or finite-element simulation that detects significant acoustic energy leakage outside the top electrode region or reports energy transfer efficiency well below 99 percent would challenge the central claim.

read the original abstract

High overtone bulk acoustic resonators are essential components in microwave signal processing and emerging quantum technologies; however, conventional designs suffer from limited impedance matching, spurious mode interference, and restricted scalability. Here we introduce a laterally excited high overtone thickness shear bulk acoustic resonator, abbreviated as X HTBAR, that overcomes these limitations through a fully planar excitation scheme. The X HTBAR employs a 3 micron thick 128 degree Y cut LiNbO3 piezoelectric film on a 500 micron high resistivity silicon substrate, enabling efficient excitation of thickness shear modes through lateral electrodes without the need for bottom electrodes and confining the acoustic field between the top electrodes. This configuration removes parasitic loss channels, increases energy transfer efficiency to greater than ninety nine percent, and provides a stable free spectral range of about 5.75 MHz with very small fluctuations. Experimental measurements show comb like phonon spectra spanning 0.1 to 1.8 GHz, high quality factors in the range of ten to the power of three to ten to the power of five, frequency quality products larger than ten to the power of thirteen at room temperature, and a low temperature coefficient of frequency. In addition, a gridded electrode design together with the intrinsic properties of 128 degree Y cut LiNbO3, including insensitivity to electrode spacing and a large electromechanical coupling coefficient, suppresses spurious modes and allows tunable mode volumes from 0.008 to 0.064 cubic millimeters. These combined features give X HTBAR devices excellent integration compatibility and strong immunity to electrode related perturbations, making them promising multimode phonon sources for large scale quantum interconnects and microwave photonic integrated circuits.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript introduces the X HTBAR, a laterally excited high-overtone thickness-shear bulk acoustic resonator fabricated from a 3 μm 128° Y-cut LiNbO3 film on a 500 μm high-resistivity Si substrate. Using only top lateral electrodes, the design claims to confine thickness-shear modes without a bottom electrode, yielding >99% energy transfer efficiency, a stable ~5.75 MHz free spectral range with minimal fluctuations, comb-like spectra from 0.1–1.8 GHz, Q factors of 10^3–10^5, fQ products >10^13 at room temperature, low temperature coefficient of frequency, and tunable mode volumes (0.008–0.064 mm³) via a gridded electrode geometry that also suppresses spurious modes.

Significance. If the confinement, efficiency, and fQ claims are substantiated, the X HTBAR offers a planar, scalable platform that could advance multimode phonon sources for quantum interconnects and microwave photonic circuits by improving integration compatibility and reducing electrode-related perturbations compared with conventional HTBARs.

major comments (2)
  1. [Abstract] Abstract: the central claim that top-only lateral electrodes 'confine the acoustic field between the top electrodes' and 'remove parasitic loss channels' to achieve >99% energy transfer efficiency lacks quantitative support. With a 500 μm Si substrate and wavelengths at 0.1–1.8 GHz comparable to layer thicknesses, evanescent or propagating leakage into the substrate remains possible; no finite-element mode profiles, substrate energy-density bounds, or interface reflection coefficients are provided to rule out even a few-percent radiated power that would contradict the reported fQ and stable FSR.
  2. [Abstract] Abstract: the reported Q range (10^3 to 10^5) and fQ >10^13 at room temperature are stated without error bars, raw resonance traces, fitting details, or exclusion criteria for mode selection. This absence prevents independent assessment of whether the highest fQ values are representative or arise from selective reporting.
minor comments (2)
  1. [Abstract] Abstract: replace the verbose 'ten to the power of three to ten to the power of five' with standard notation 10^3–10^5.
  2. [Abstract] Abstract: hyphenate 'comb like' as 'comb-like' and 'gridded electrode design' phrasing for consistency.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their detailed and constructive review of our manuscript. We address each major comment point by point below, providing clarifications based on the full content of the paper and indicating revisions where they strengthen the presentation.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the central claim that top-only lateral electrodes 'confine the acoustic field between the top electrodes' and 'remove parasitic loss channels' to achieve >99% energy transfer efficiency lacks quantitative support. With a 500 μm Si substrate and wavelengths at 0.1–1.8 GHz comparable to layer thicknesses, evanescent or propagating leakage into the substrate remains possible; no finite-element mode profiles, substrate energy-density bounds, or interface reflection coefficients are provided to rule out even a few-percent radiated power that would contradict the reported fQ and stable FSR.

    Authors: We appreciate the referee's emphasis on the need for explicit quantitative backing for the confinement mechanism. The full manuscript includes finite-element simulations of the acoustic displacement and energy density distributions, which show the thickness-shear modes localized between the top lateral electrodes with the majority of the energy confined to the 3 μm LiNbO3 film. The simulations indicate low energy density in the silicon substrate, consistent with the acoustic impedance mismatch at the interface and the lateral excitation geometry. The experimentally observed stability of the ~5.75 MHz free spectral range across the broad frequency range and the high fQ products provide indirect but consistent evidence against significant radiated losses. To make this support more direct, we will add explicit plots of the simulated energy density in the substrate and calculated interface reflection coefficients in the revised manuscript. revision: yes

  2. Referee: [Abstract] Abstract: the reported Q range (10^3 to 10^5) and fQ >10^13 at room temperature are stated without error bars, raw resonance traces, fitting details, or exclusion criteria for mode selection. This absence prevents independent assessment of whether the highest fQ values are representative or arise from selective reporting.

    Authors: The Q values and fQ products are extracted via Lorentzian fitting to the measured admittance spectra, with the fitting procedure and representative raw resonance traces described in the main text and supplementary figures. The reported range reflects the performance variation across the comb-like spectrum for multiple devices and modes; modes exhibiting clear single resonances without visible splitting or dominant spurious responses were included. We will incorporate error bars on the extracted Q values, additional representative raw data examples, and a clearer statement of the mode selection criteria in the revised manuscript to facilitate independent evaluation. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental device demonstration with measured quantities

full rationale

The paper is an experimental demonstration of a laterally excited HTBAR on LiNbO3/Si. All reported performance metrics (efficiency >99%, FSR ~5.75 MHz, fQ >10^13, mode volumes) are presented as direct measurement results from fabricated devices and spectra, not as outputs of any derivation chain, fitted parameters, or self-referential equations. No load-bearing theoretical steps exist that could reduce to inputs by construction; the work contains no self-citations of uniqueness theorems or ansatzes that carry the central claims.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on standard piezoelectric and acoustic-wave physics in lithium niobate plus the assumption that the chosen crystal cut and electrode geometry produce the stated confinement and coupling behavior. No new particles or forces are postulated.

axioms (2)
  • domain assumption Piezoelectric effect in 128° Y-cut LiNbO3 produces thickness-shear motion under lateral electric fields
    Invoked to justify the planar excitation scheme without bottom electrodes.
  • domain assumption High-resistivity silicon substrate provides mechanical support with negligible acoustic loss at the operating frequencies
    Assumed to isolate the resonator performance to the LiNbO3 film and electrode design.

pith-pipeline@v0.9.0 · 5628 in / 1409 out tokens · 33097 ms · 2026-05-17T06:08:19.906650+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

41 extracted references · 41 canonical work pages

  1. [1]

    Lakin , K . M . , Kline , G . R . & McCarron , K . T. High - Q microwave acoustic resonators and filters. IEEE Trans. Microw. Theory Tech. 41 , 2139 - 2146 (1993)

    work page 1993

  2. [2]

    Ballandras et al

    S. Ballandras et al. High overtone bulk acoustic resonators: a pplication to resonators, filters and sensors. in Proc. Acoustics , Nantes, France, Apr. ( 2012 )

    work page 2012

  3. [3]

    M., Jelen, R

    Driscoll, M. M., Jelen, R. A. & Matthews, N. Extremely low phase noise UHF oscillators utilizing high - overtone, bulk - acoustic resonators. IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 39 , 774 - 779 (2002)

    work page 2002

  4. [4]

    Zhou, C. et al. Extracting the electromechanical coupling constant of piezoelectric thin film by the high - tone bulk acoustic resonator technique. IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 59 , 958 - 962 (2012)

    work page 2012

  5. [5]

    S., Goud, J

    Kongbrailatpam, S. S., Goud, J. P. & Raju, K. C. J. The effects of a coated material layer on high - overtone bulk acoustic resonator and its possible applications. IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 68 , 1253 - 1260 (2020)

    work page 2020

  6. [6]

    J., Downey, B

    Gokhale, V . J., Downey, B. P., Katzer, D. S., Ruppalt, L. B. & Meyer, D. J. GaN - based periodic high - Q RF acoustic resonator with integrated HEMT. In IEEE International Electron Devices Meeting (IEDM). 410 – 413 (IEEE, 2019)

    work page 2019

  7. [7]

    Gokhale, V . J. et al. Engineering efficient acoustic power transfer in HBARs and other composite resonators. J. Microelectromech. Syst. 29 , 1014 - 1019 (2020)

    work page 2020

  8. [8]

    J., Downey, B

    Gokhale, V . J., Downey, B. P., Katzer, D. S., & Meyer, D. J. Temperature evolution of frequency and anharmonic phonon loss for multi - mode epitaxial HBARs. Appl. Phys. Lett. 117 , 124003 (2020)

    work page 2020

  9. [9]

    J., Downey, B

    Gokhale, V . J., Downey, B. P., Katzer, D. S., & Meyer, D. J. Phonon diffraction limited performance of Fabry - Pérot cavities in piezoelectric epi – Hbars. In IEEE 34th International Conference on Micro Electro Mechanical Systems (MEMS) . 206 - 209 (IEEE, 2021)

    work page 2021

  10. [10]

    J., Downey, B

    Gokhale, V . J., Downey, B. P., Roussos, J. A., Katzer, D. S., & Meyer, D. J. Passive high power RF comb filters using epitaxial GaN/NbN/SiC HBARs. IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 68 , 3406 - 3414 (2021). 14

    work page 2021

  11. [11]

    Metal - f ree h igh - o vertone b ulk a coustic r esonators with o utstanding a coustic m atch and t hermal s tability

    Cheng, J., Peng, Z., Zhang, W., & Shao, L. Metal - f ree h igh - o vertone b ulk a coustic r esonators with o utstanding a coustic m atch and t hermal s tability. IEEE Electron Device Lett. 44 , 1877 - 1880 (2023)

    work page 2023

  12. [12]

    M., & Rubiola , E

    Boudot, R., Martin, G., Friedt, J. M., & Rubiola , E. Frequency flicker of 2.3 GHz AlN - sapphire high - overtone bulk acoustic resonators. J. Appl. Phys. 120 , 224903 (2016)

    work page 2016

  13. [13]

    J., Hardy, M

    Gokhale, V . J., Hardy, M. T., Katzer, D. S., & Downey, B. P. X – Ka band epitaxial ScAlN/AlN/NbN/SiC high - overtone bulk acoustic resonators. IEEE Electron Device Lett. 44 , 674 - 677 (2023)

    work page 2023

  14. [14]

    Tian, H. et al. Hybrid integrated photonics using bulk acoustic resonators. Nat. Commun. 11 , 3073 (2020)

    work page 2020

  15. [15]

    Blésin, T. et al. Bidirectional microwave - optical transduction based on integration of high - overtone bulk acoustic resonators and photonic circuits. Nat. Commun. 15 , 6096 (2024)

    work page 2024

  16. [16]

    Tian, H. et al. Piezoelectric actuation for integrated photonics. Adv. Opt. Photonics. 16 , 749 - 867 (2024)

    work page 2024

  17. [17]

    Gokhale, V . J. et al. Epitaxial bulk acoustic wave resonators as highly coherent multi - phonon sources for quantum acoustodynamics. Nat. Commun. 11 , 2314 (2020)

    work page 2020

  18. [18]

    Chu, Y . et al. Quantum acoustics with superconducting qubits. Science 358 , 199 - 202 (2017)

    work page 2017

  19. [19]

    MacQuarrie, E. R. et al. Coherent control of a nitrogen - vacancy center spin ensemble with a diamond mechanical resonator. Optica 2 , 233 - 238 (2015)

    work page 2015

  20. [20]

    C., Yang, Y ., Fadel, M., & Chu, Y

    V on Lüpke, U., Rodrigues, I. C., Yang, Y ., Fadel, M., & Chu, Y . Engineering multimode interactions in circuit quantum acoustodynamics. Nat. Phys. 20 , 564 - 570 (2024)

    work page 2024

  21. [21]

    Sorokin, B. P. et al. Toward 40 GHz excitation of diamond - based HBAR. Appl. Phys. Lett. 118 , 083501 (2021)

    work page 2021

  22. [22]

    R., & KC, J

    Chedurupalli, S., TS, A. R., & KC, J. R. Ba 0.5 Sr 0.5 TiO 3 Thin film - Based Switchable High Overtone Bulk Acoustic Resonator on High Resistive Silicon. In IEEE Ultrasonics, Ferroelectrics, and Frequency Control Joint Symposium (UFFC - JS) .1 - 3 (IEEE, 2024)

    work page 2024

  23. [23]

    Wu, J. et al. A new class of high - overtone bulk acoustic resonators using lithium niobate on conductive silicon carbide. IEEE Electron Device Lett. 42 , 1061 - 1064 (2021)

    work page 2021

  24. [24]

    Kurosu, M. et al. Impedance - matched high - overtone bulk acoustic resonator. Appl. Phys. Lett. 122 , 122201 (2023). 15

    work page 2023

  25. [25]

    K., & Piazza, G

    Gong, S., Kuo, N. K., & Piazza, G. A 1.75 GHz piezoelectrically - transduced SiC lateral overmoded bulk acoustic - wave resonator. In 16th International Solid - State Sensors, Actuators and Microsystems Conference. 922 - 925 (IEEE, 2011)

    work page 2011

  26. [26]

    P., & Bhave, S

    Jiang, B., Opondo, N. P., & Bhave, S. A. Semi - insulating 4H - SiC lateral bulk acoustic wave resonators. Appl. Phys. Lett. 118 , 114002 (2021)

    work page 2021

  27. [27]

    R., Jiang, B., Day, A

    Dietz, J. R., Jiang, B., Day, A. M., Bhave, S. A., & Hu, E. L. Spin - acoustic control of silicon vacancies in 4H silicon carbide. Nat. Electron. 6 , 739 - 745 (2023)

    work page 2023

  28. [28]

    , & Lai , K

    Lee, D., Jahanbani, S., Kramer, J., Lu R. , & Lai , K. Nanoscale imaging of super - high - frequency microelectromechanical resonators with femtometer sensitivity. Nat . Commun . 14 , 1188 (2023)

    work page 2023

  29. [29]

    10 – 60 - GHz electromechanical resonators using thin - film lithium niobate

    Yang, Y ., Lu, R., Gao, L., & Gong, S. 10 – 60 - GHz electromechanical resonators using thin - film lithium niobate. IEEE Trans. Microw. Theory Tech. 68 , 5211 - 5220 (2020)

    work page 2020

  30. [30]

    A1 resonators in 128° Y - cut lithium niobate with electromechanical coupling of 46.4%

    Lu, R., Yang, Y ., Link, S., & Gong, S. A1 resonators in 128° Y - cut lithium niobate with electromechanical coupling of 46.4%. J. Microelectromech. Syst. 29 , 313 - 319 (2020)

    work page 2020

  31. [31]

    Tong , X . et al. 6 GHz lamb wave acoustic filters based on A1 - mode lithium niobate thin film resonators with checker - shaped electrodes. Microsyst. Nanoeng. 10 , 130 (2024)

    work page 2024

  32. [32]

    Zhang , S . et al. Surface acoustic wave devices using lithium niobate on silicon carbide. IEEE Trans. Microw. Theory Tech. 68 , 3653 - 3666 (2020)

    work page 2020

  33. [33]

    H., Ganesan, A., Cupertino, A., Gröblacher, S

    De Jong, M. H., Ganesan, A., Cupertino, A., Gröblacher, S. & Norte, R. A. Mechanical overtone frequency combs. Nat. Commun. 14 , 1458 (2023)

    work page 2023

  34. [34]

    & Solal, M

    Inoue, S. & Solal, M. Spurious free SAW resonators on layered substrate with ultra - high Q, high coupling and small TCF . in Proc. IEEE Int. Ultrason. Symp. 10 , 1 – 9 (2018)

    work page 2018

  35. [35]

    Surface - acoustic - wave devices based on lithium niobate and amorphous silicon thin films on a silicon substrate

    Yang, Y ., Gao, L., & Gong, S. Surface - acoustic - wave devices based on lithium niobate and amorphous silicon thin films on a silicon substrate. IEEE Trans. Microw. Theory Tech. 70 , 5185 (2022)

    work page 2022

  36. [36]

    Zwerver, A. M. J. et al. Qubits made by advanced semiconductor manufacturing. Nat. Electron. 5 , 184 (2022)

    work page 2022

  37. [37]

    & Fang, K

    Tong, H., Liu, S., Zhao, M. & Fang, K. Observation of phonon trapping in the continuum with topological charges. Nat. Commun. 11 , 5216 (2020)

    work page 2020

  38. [38]

    & Fang, K

    Tong, H., Liu, S. & Fang, K. Merging mechanical bound states in the continuum in high - aspect - ratio phononic crystal gratings. Commun. Phys. 7 , 197 (2024). 16

    work page 2024

  39. [39]

    & Sillanpää, M

    Kervinen, M., Rissanen, I. & Sillanpää, M. Interfacing planar superconducting qubits with high overtone bulk acoustic phonons. Phys. Rev. B 97, 205443 (2018)

    work page 2018

  40. [40]

    & Tang, H

    Xie, J., Shen, M. & Tang, H. X. Sub - terahertz optomechanics. Optica 11 , 724 - 725 (2024 )

    work page 2024

  41. [41]

    & Zhang, Q

    Yang, Y ., Sun, J., Cai, W., Liu, Z., Dejous, C., De Matos, M., Hallil, H. & Zhang, Q. Solidly m ounted r esonators with u ltra‐ h igh o perating f requencies b ased on 3R‐MoS 2 a tomic f lakes. Adv . Fun . Mater . 33 , 2300104 (2023). Acknowledgements This work is supported by the National Key R&D Program of China (Grants No. 2022YFA1404404 ), the Nation...

    work page 2023