Higher order lamb wave acoustic devices with complementarily-oriented piezoelectric layers

An acoustic delay line comprising:

• a stack of at least two piezoelectric layers configured to propagate a Lamb wave in a mode having an order corresponding to a number of piezoelectric layers of the stack, wherein the stack comprises a first piezoelectric layer and a second piezoelectric layer disposed on the first piezoelectric layer, and wherein the first piezoelectric layer has a first cut plane orientation and the second piezoelectric layer has a second cut plane orientation that is complementary to the first cut plane orientation;
• a first interdigitated transducer (IDT) disposed on at least one of a top surface of the stack or a bottom surface of the stack at a first end of the stack and configured to convert, into the Lamb wave, a first electromagnetic signal traveling along a length of the stack;
• and
• a second IDT disposed on the at least one of the top surface or the bottom surface at a second end of the stack with a gap between the second IDT and the first IDT, the second IDT being configured to convert the Lamb wave into a second electromagnetic signal after a time delay affected by a gap length of the gap.