arXiv subjects

Ming-Huang Li

Publications and source records attributed to Ming-Huang Li.

5 recordsLinked to original sources

arXiv2024

Low-Loss Higher-Order Cross-Sectional Lamé Mode SAW Devices in 10-20 GHz Range

This paper presents surface acoustic wave (SAW) acoustic delay lines (ADL) for studying propagation loss mechanisms in Lithium Niobate (LN). Devices were fabricated by depositing 50 nm aluminum patterns on 600 nm X-Cut LN on amorphous silicon on silicon carbide, where longitudinally dominant SAW was targeted. Upon fabrication, higher-order thickness-based cross-sectional Lamé modes and Rayleigh modes were studied for their Q factors using acoustic delay lines. Utilizing bi-directional electrodes, ADL with lateral lambda values ranging from 0.4 um to 0.6 um were measured. Higher order Lame modes were found to have consistently higher Q factors than their Rayleigh mode counterpart, on the order of 1000-3000, showing high-frequency SAW devices as still viable candidates for frequency scaling without a substantial increase in loss.

physics.app-ph↗

arXiv2024

C-Band Lithium Niobate on Silicon Carbide SAW Resonator With Figure-of-Merit of 124 at 6.5 GHz

In this work, we demonstrate a C-band shear-horizontal surface acoustic wave (SH-SAW) resonator with high electromechanical coupling (kt2) of 22% and a quality factor (Q) of 565 based on a thin-film lithium niobate (LN) on silicon carbide (SiC) platform, featuring an excellent figure-of-merit (FoM = kt2*Q ) of 124 at 6.5 GHz, the highest FoM reported in this frequency range. The resonator frequency upscaling is achieved through wavelength ($λ$) reduction and the use of thin aluminum (Al) electrodes. The LN/SiC waveguide and synchronous resonator design collectively enable effective acoustic energy confinement for a high FoM, even when the normalized thickness of LN approaches a scale of 0.5$λ$ to 1$λ$. To perform a comprehensive study, we also designed and fabricated five additional resonators, expending the $λ$ studied ranging from 480 to 800 nm, in the same 500 nm-thick transferred Y-cut thin-film LN on SiC. The fabricated SH-SAW resonators, operating from 5 to 8 GHz, experimentally demonstrate a kt2 from 20.3% to 22.9% and a Q from 350 to 575, thereby covering the entire C-band with excellent performance.

eess.SP↗

arXiv2024

Thin-film Lithium Niobate on Insulator Surface Acoustic Wave Devices for 6G Centimeter Bands

In this work, we investigate the frequency scaling of shear-horizontal (S.H.) surface acoustic wave (SAW) resonators based on a lithium niobate on insulator (LNOI) substrate into the centimeter bands for 6G wireless systems. Prototyped resonators with wavelengths ranging between 240 nm and 400 nm were fabricated, and the experimental results exhibit a successful frequency scaling between 9.05 and 13.37 GHz. However, a noticeable performance degradation can be observed as the resonance frequency (fs) scales. Such an effect is expected to be caused by non-ideal helec/λ for smaller λ devices. The optimized LNOI SH-SAW with a λ of 400 nm exhibits a fs of 9.05 GHz, a keff2 of 15%, Qmax of 213 and a FoM of 32, which indicates a successful implementation for device targeting centimeter bands.

eess.SP↗

arXiv2019

5-GHz Antisymmetric Mode Acoustic Delay Lines in Lithium Niobate Thin Film

We present the first group of acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in Z-cut lithium niobate thin films. The demonstrated ADLs significantly surpass the operation frequency of the previous works with similar feature sizes, because of its simultaneously fast phase velocity, large coupling coefficient, and low-loss. In this work, the propagation characteristics of the A1 mode in lithium niobate is analytically modeled and validated with finite element analysis. The design space of A1 ADLs is then investigated, including both the fundamental design parameters and those introduced from the practical implementation. The implemented ADLs at 5 GHz show a minimum insertion loss of 7.94 dB, an average IL of 9.1 dB, and a fractional bandwidth around 4%, with delays ranging between 15 ns to 109 ns and the center frequencies between 4.5 GHz and 5.25 GHz. The propagation characteristics of A1 mode acoustic waves have also been extracted for the first time. The A1 ADL platform can potentially enable wide-band high-frequency passive signal processing functions for future 5G applications in the sub-6 GHz spectrum bands.

eess.SP↗

arXiv2019

Acoustically Driven and Modulation Inducible Radiating Elements

The low propagation loss of electromagnetic radiation below 1 MHz offers significant opportunities for low power, long range communication systems to meet growing demands for IoT applications. Especially in the very low frequency (VLF: 3-30 kHz) range and lower, propagation through tens of meters of seawater, hundreds of meters of earth, and hundreds of kilometers of air with only 2-3 dB of loss is possible. However, the fundamental reduction in efficiency as the size of electrical antennas decreases below a wavelength (30 m at 1 MHz) has made portable communication systems in the VLF and low frequency (LF: 30-300 kHz) ranges impractical for decades. A paradigm shift from electrical to piezoelectric antennas utilizing strain-driven currents at resonant wavelengths up to five orders of magnitude smaller than electrical antennas offers the promise for orders of magnitude efficiency improvement over the electrical state-of-the-art. This work demonstrates a lead zirconate titanate transmitter >6000 times more efficient than a comparably sized electrical antenna and capable of bit rates up to 60 bit/s using frequency-shift keying. Detailed analysis of design parameters offers a roadmap for significant future improvement in both radiation efficiency and data rate in the new field of acoustically driven antennas.

physics.app-ph↗