Phonon engineering enables hyperbolic asymptotic line polaritons

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanophotonics

Background:

• Polaritonic materials enable control of light-matter interactions at the nanoscale.
• Conventional polariton modulation methods face limitations due to momentum-matching requirements.

Purpose of the Study:

• To propose a phonon-engineering strategy to overcome momentum-matching limitations in polariton modulation.
• To achieve tunable hyperbolic polaritons in high-symmetry materials.

Main Methods:

• Utilized anisotropic phononic materials (α-MoO3) to engineer phonon-induced dielectric oscillations.
• Transformed circular surface polaritons into hyperbolic asymptotic line polaritons (HALPs) in AlN.
• Investigated broadband modulation and tuning of HALP isofrequency contours.

Main Results:

• Achieved broadband modulation of HALPs in AlN with a ~90° tuning range for the open angle.
• Demonstrated precise phase control for diffraction-free, zero-phase propagation.
• Showcased tunability of HALP propagation via atomic isotope and crystal structure control.

Conclusions:

• Phonon-engineering offers a viable route to achieve hyperbolic polaritons in high-symmetry materials.
• The developed strategy circumvents momentum-matching constraints for polariton modulation.
• This approach holds potential for generalized applications in nanophotonics and optical device design.