Cryogenic Characterization of Low-Loss Thin-film Lithium Niobate on Sapphire Shear Horizontal Surface Acoustic Wave Devices.

This paper reports a cryogenic study on wideband shear horizontal surface acoustic wave (SH-SAW) devices based on an emerging Y-cut LiNbO/SiO/Sapphire (LNOS) platform. To perform a comprehensive study, low-loss acoustic delay lines (ADLs) equipped with unidirectional transducers were designed with a wavelength (λ) of 4 μm (900 MHz) and a wide fractional bandwidth (FBW) of around 7%, featuring various physical delays ranging from 5λ to 200λ as testing structures. By cooling the temperature down to 5 K, the insertion loss (IL) of the longest ADL and the extracted propagation loss (PL) were characterized as 4.