Electrically Tunable Suspended Acoustic Mach-Zehnder Interferometer Based on Alscn Thin Films

Electrically tunable suspended acoustic Mach-Zehnder interferometer (MZI) on aluminum scandium nitride ($\text{Al}_{0.7} \text{Sc}_{0.3} ~\mathrm{N}$) thin films that converts differential phase control into amplitude modulation was fabricated and characterized. By applying equal-magnitude, oppositepolarity DC biases to the two arms, the device achieves a maximum transmission tunability of 33.7 dB at 1.747 GHz with only 156 nW power consumption. Finite-element simulations and measurements confirm that in phase and out of phase interference can be reconfigured with near-zero static power. The results establish suspended AlScN MZIs as scalable building blocks for adaptive RF front ends, on-chip analog modulation, and programmable acoustic computing.