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130 results on '"Lu, Ruochen"'

24. Acoustic Loss of GHz Higher-Order Lamb Waves in Thin-Film Lithium Niobate: A Comparative Study.

Author

Lu, Ruochen, Yang, Yansong, and Gong, Songbin

Subjects
*LAMB waves, *SOUND-wave attenuation, *LITHIUM niobate, *DELAY lines, *QUALITY factor, *COMPARATIVE studies
Abstract

This work reports a comparative study of acoustic loss between different Lamb waves at GHz in thin-film lithium niobate (LiNbO3). The propagation loss (PL) of higher-order Lamb waves in thin-film LiNbO3 is studied for the first time using acoustic delay line (ADL) testbeds. The acoustic wave attenuation and quality factors ($Q$) of different Lamb waves are extracted, showing higher $Q\text{s}$ for higher-order Lamb modes than fundamental modes in air and vacuum at room temperature. The extracted $Q\text{s}$ are higher than those reported in thin-film LiNbO3 resonators, implying the electrode and anchor-induced loss as the dominant loss factors. The ADL-based loss analysis framework is readily extendable to acoustic damping study in other microwave acoustic platforms. [2021-0165] [ABSTRACT FROM AUTHOR]

Published
2021
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33. Acoustic Loss in Thin-Film Lithium Niobate: An Experimental Study.

Author

Lu, Ruochen, Yang, Yansong, and Gong, Songbin

Subjects
*DELAY lines, *QUALITY factor, *THIN films, *LITHIUM niobate, *CRYSTAL resonators, *MICROFABRICATION
Abstract

This work reports an experimental study of acoustic loss in thin-film lithium niobate (LiNbO3) using acoustic delay lines (ADLs). Unlike prior resonator-based quality factor (Q) studies, this approach directly extracts the damping in thin-film LiNbO3, avoiding the influence of other intricate loss mechanisms, e.g., anchor loss and electrode-induced loss. Acoustic attenuation of fundamental symmetric (S0) and shear horizontal (SH0) waves are studied in suspended LiNbO3 thin films of different thicknesses. The attenuation is significantly higher in thinner LiNbO3 films, suggesting the LiNbO3 crystal degradation during the microfabrication as the primary loss origin. Nevertheless, the extracted equivalent Q in thin-film LiNbO3 is still higher than reported values, suggesting that anchor design and electrode quality remain the bottlenecks for higher Q. The proposed loss extraction framework is readily extendable to other acoustic thin-film structures. [2021-0107] [ABSTRACT FROM AUTHOR]

Published
2021
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34. Near-Zero Drift and High Electromechanical Coupling Acoustic Resonators at > 3.5 GHz.

Author

Hassanien, Ahmed E., Lu, Ruochen, and Gong, Songbin

Subjects
*ACOUSTIC resonators, *ACOUSTIC couplers, *LAMB waves, *SOUND waves, *ACOUSTIC surface waves, *LITHIUM niobate
Abstract

In this article, near-zero drift and high electromechanical coupling acoustic resonators have been designed and demonstrated. The acoustic resonator is based on Lamb acoustic waves in a bimorph composed of lithium niobate on silicon dioxide. Our approach breaks through a performance boundary in conventional Lamb-wave resonators by introducing the bimorph while operating at higher order resonant modes. This enables the resonator to achieve frequency scalability, a low-temperature coefficient of frequency, and high electromechanical coupling altogether. The electromechanical coupling and temperature coefficient of the resonator were analytically optimized for the A3 mode through adjusting the thicknesses of different materials in the bimorph. Resonators with different dimensions and stack thickness were fabricated and measured, resulting in a temperature coefficient of frequency ranging from −17.6 to −1.1 ppm/°C, high electromechanical coupling ranging from 13.4% to 18%, and quality factors up to 800 at 3.5 GHz. The achieved specifications are adequate for fifth-generation (5G) sub-6-GHz frequency bands n77 and n78. [ABSTRACT FROM AUTHOR]

Published
2021
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35. Gigahertz Low-Loss and High Power Handling Acoustic Delay Lines Using Thin-Film Lithium-Niobate-on-Sapphire.

Author

Lu, Ruochen, Yang, Yansong, Hassanien, Ahmed E., and Gong, Songbin

Subjects
*DELAY lines, *ACOUSTIC surface waves, *GROUP velocity, *SAPPHIRES, *PHASE velocity, *LITHIUM niobate, *INSERTION loss (Telecommunication)
Abstract

In this work, we present the first group of gigahertz low-loss, wideband, and high power handling delay lines (ADLs) using a thin-film lithium niobate (LiNbO3)-on-sapphire platform. The ADLs leverage a single-phase unidirectional transducer (SPUDT) to efficiently excite the shear horizontal surface acoustic wave (SH-SAW) in the film stack. The fabricated miniature SH-SAW ADL at 1.1 GHz shows a low insertion loss (IL) of 2.8 dB, a wide fractional bandwidth (FBW) of 6.14%, and a fast phase velocity of 5127 m/s. The device also features a high 1-dB compression point (P1dB) of 30.4 dBm. The temperature coefficient of frequency is −45 ppm/K. ADLs with delays between 12 and 172 ns have been implemented, with IL between 2.8 and 8.3 dB. SH-SAW propagation characteristics are extracted, showing a group velocity of 4747 m/s and a propagation loss of 6.73 dB/mm or 31.9 dB/ $\mu \text{s}$. The simultaneous low-loss and high power handling illustrate the great potential of LiNbO3-on-sapphire for RF and cross domain applications at gigahertz. [ABSTRACT FROM AUTHOR]

Published
2021
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36. Lateral Spurious Mode Suppression in Lithium Niobate A1 Resonators.

Author

Yang, Yansong, Gao, Liuqing, Lu, Ruochen, and Gong, Songbin

Subjects
LITHIUM niobate, LAMB waves, RESONATORS, QUALITY factor, LITHIUM cell electrodes, ELECTRICAL load, MEMS resonators
Abstract

This work presents an improved design that exploits dispersion matching to suppress the spurious modes in the lithium niobate first-order antisymmetric (A1) Lamb wave mode resonators. The dispersion matching in this work is achieved by micro-machining the lithium niobate thin film to balance the electrical and mechanical loadings of electrodes. In this article, the dispersion matchings of the A1 mode in lithium niobate based on different metals are analytically modeled and validated with finite-element analysis. The fabricated devices exhibit spurious-free responses with a quality factor of 692 and an electromechanical coupling coefficient of 28%. The demonstrated method herein could overcome a significant hurdle that is currently impeding the commercialization of A1 devices. [ABSTRACT FROM AUTHOR]

Published
2021
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38. A -106dBm 33nW Bit-Level Duty-Cycled Tuned RF Wake-up Receiver

Author

Moody, Jesse, primary, Dissanayake, Anjana, additional, Bishop, Henry, additional, Lu, Ruochen, additional, Liu, Ningxi, additional, Duvvuri, Divya, additional, Gao, Anming, additional, Truesdell, Daniel, additional, Barker, N. Scott, additional, Gong, Songbin, additional, Calhoun, Benton H, additional, and Bowers, Steven M, additional

Published
2019
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