Acoustic Mach-Zehnder interferometer utilizing self-collimated beams in a two-dimensional phononic crystal

- Mach-Zehnder interferometer in a two-dimensional phononic crystal.
- Unidirectional operation for self-collimated beams in symmetric (all-water) case.
- Unidirectionality disrupted for an ethanol-water mixture in sample compartment.
- Transmittances through terminals vary as a cosine squared function of ethanol ratio.
- Contrast ratio to be a good measure of ethanol content.