Gabriel Vidal-Alvarez

Low loss delay lines based on suspended thin film of X-cut lithium niobate

Analog signal processing techniques based on surface acoustic wave (SAW) devices have been commercialized in the past 50 years. Delay lines [1] and resonators [2] have been implemented for a wide range of applications [3]. The use of small scale resonators has boomed because of the continuous growth of the cell phone business, whereas components such as delay lines have been relegated to smaller markets such as base stations. Emerging applications related to the Internet of Things have brought up the need for extremely low power and high speed signal processors. The maximum electromechanical coupling (kt2) of surface acoustics waves in lithium niobate (LiNbO3, dubbed LN) is 5.6 % [4]. Lamb waves resonators fabricated on suspended thin films of LN have demonstrated a kt2 around 30 % [5]. Taking advantage of such high kt2 to build delay lines is extremely beneficiary. However, due to the nature of Lamb waves, which require suspended plates, achieving long delays poses an important fabrication challenge. We overcome this technological challenge in this work.