Negative Refraction Guided by a Glide-Reflection Symmetric Crystal Interface

Area of Science:

• Acoustics
• Condensed Matter Physics
• Materials Science

Background:

• Phononic crystals (PCs) with negative refractive indices are key for ultra-high-resolution acoustic lenses.
• Achieving negative refraction in acoustic systems is an active area of research.

Purpose of the Study:

• To present a novel glide-reflection (GR) symmetrical phononic crystal (PC) design.
• To demonstrate negative refraction using edge states (ESs) and coupled edge states (CESs).
• To provide a new methodology for designing acoustic negative refraction devices.

Main Methods:

• Design of GR symmetrical phononic crystals.
• Excitation of edge states (ESs) via Wannier center mismatch.
• Stacking of GR symmetric PC interfaces to form coupled edge states (CESs).
• Finite element method (FEM) simulations for verification.

Main Results:

• Emergence of ESs due to Wannier center mismatch in GR symmetric PCs.
• Achieved negative refraction by exciting ESs with negative dispersion.
• Observation of CESs from coupling between adjacent GR symmetric PC interfaces.
• Demonstrated stronger negative sound refraction with negative transverse displacement via CESs.

Conclusions:

• The proposed GR symmetrical PC structure effectively achieves negative refraction.
• Coupled edge states (CESs) enhance negative sound refraction effects.
• This work offers a novel approach for the design of acoustic negative refraction and ultra-high-resolution acoustic lenses.