Acoustic wave element, acoustic wave filter device, and multiplexer

An acoustic wave element comprising:

• a piezoelectric layer;
• interdigital transducer (IDT) electrodes on two main surfaces of the piezoelectric layer;
• and
• a plurality of reflectors on both of the two main surfaces;
• wherein
• the IDT electrodes each include a pair of comb-shaped electrodes that are opposite to each other;
• each of the comb-shaped electrodes defining the pair of comb-shaped electrodes includes a plurality of electrode fingers extending in a second direction that intersects a first direction in a direction along a main surface of the piezoelectric layer, and a busbar electrode connecting single ends of the plurality of electrode fingers;
• the plurality of reflectors are arranged on two outer sides of the IDT electrode in the first direction and each include a plurality of reflection electrode fingers extending in the second direction;
• and
• in a case where:
• an array pitch of the plurality of electrode fingers arranged along the first direction is represented by Pi;
• an array pitch of the plurality of reflection electrode fingers arranged along the first direction is represented by Pr;
• and
• an IDT-reflector gap in the first direction between a center of an electrode finger that is closest to the reflector among the plurality of electrode fingers and a center of a reflection electrode finger that is closest to the IDT electrode among the plurality of reflection electrode fingers is represented by G;
• a thickness of the piezoelectric layer is smaller than or equal to a value that is about twice Pi;
• G is smaller than Pr;
• and
• Pr is greater than Pi.