Acoustic wave device

An acoustic wave device comprising:

• a first resonator including:
• a piezoelectric substrate including a piezoelectric layer;
• a first functional electrode on the piezoelectric layer;
• and
• a first dielectric film on the piezoelectric layer and covering the first functional electrode;
• and
• a second resonator that includes the piezoelectric layer, the second resonator including:
• a second functional electrode on the piezoelectric layer;
• and
• a second dielectric film on the piezoelectric layer and covering the second functional electrode,
• wherein the piezoelectric layer includes a first resonator portion and a second resonator portion, a portion of the first resonator being in the first resonator portion, a portion of the second resonator being in the second resonator portion;
• wherein a resonant frequency of the first resonator is lower than a resonant frequency of the second resonator and, in the piezoelectric layer, a thickness of the first resonator portion is greater than a thickness of the second resonator portion, and
• wherein ts1/tp1≤ts2/tp2, where tp1 is the thickness of the first resonator portion, tp2 is the thickness of the second resonator portion, ts1 is a thickness of the first dielectric film, and tp2 is a thickness of the second dielectric film.