Realization of Complex 3-D Phononic Crystals With Wide Complete Acoustic Band Gaps

Phononic crystals (PnCs) offer unique band structures for acoustic wave propagation. Fabricating intricate three-dimensional (3-D) PnCs allows a new class of devices with complex phononic band structures beyond capabilities of two-dimensional (2-D) designs. We have successfully fabricated novel 3-D PnCs with 1-mm lattice constant and minimum feature sizes as low as
$100\;\upmu\text{m}$
using high-resolution stereolithography printing. Here, we report the first theoretical calculations and experimental results demonstrating wide complete 3-D phononic band gaps not attainable by corresponding 2-D structures with the same lattice geometry. Longitudinal and shear-wave propagation is suppressed by more than
$-60\;\text{dB}$
in frequency bands as wide as 400 kHz to 1 MHz.