US Patent 7230509 Acoustic mirror

An acoustic mirror includes constituent layers that are substantially odd multiples of λ/4. The constituent layers include a first impedance layer and a second impedance layer, where the first impedance layer includes a first material having a first acoustic impedance and a first dielectric constant, and the second impedance layer includes a second material having a second acoustic impedance and a second dielectric constant. The second acoustic impedance is higher than the first acoustic impedance, and the first dielectric constant is lower than the second dielectric constant.