An On-Chip Second-Order Elastic Topological Insulator for Demultiplexing Out-of-Plane and In-Plane Corner Modes

Area of Science:

• Condensed Matter Physics
• Materials Science
• Acoustics

Background:

• Second-order elastic topological insulators (SETIs) offer unique localized corner states for elastic wave manipulation.
• Current SETIs are limited to supporting only a single mode (either in-plane or out-of-plane) of corner states.

Purpose of the Study:

• To introduce and demonstrate an on-chip SETI that simultaneously supports both high-frequency out-of-plane and in-plane elastic corner states.
• To enable selective excitation and demultiplexing of these dual-mode corner states.

Main Methods:

• Design and fabrication of a novel on-chip second-order elastic topological insulator.
• Experimental validation of the presence of both out-of-plane and in-plane corner states.
• Frequency-dependent excitation experiments to demonstrate selective mode control.

Main Results:

• Successfully realized an on-chip SETI hosting simultaneous out-of-plane and in-plane corner states at approximately 0.2 MHz.
• Experimentally confirmed the existence of these dual corner states.
• Demonstrated selective excitation of individual modes by tuning the excitation frequency.

Conclusions:

• The developed SETI platform enables simultaneous manipulation of distinct elastic wave modes.
• This capability facilitates the demultiplexing of out-of-plane and in-plane corner states, paving the way for multifunctional elastic devices.
• The simple, scalable design is suitable for integration into on-chip elastic circuits and micro-electromechanical systems (MEMS).