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Piezoreflectance Spectroscopy of Optical Transitions in van der Waals Layered Crystals
Published on: May 22, 2026
Mid-infrared long-range surface polaritons in two-dimensional van der Waals materials
Mingsong Wang1, Shixiong Yin1,2, Saroj Chand1
1Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY 10031, USA.
Science Advances
|August 5, 2026
Summary
Researchers demonstrate long-range surface polaritons (LRSPs) in 2D van der Waals materials, achieving significantly longer propagation distances for mid-infrared photonic devices. This breakthrough offers new possibilities for high-speed on-chip applications.
Area of Science:
- Photonics and Materials Science
- Optics and Light-Matter Interactions
Background:
- Graphene plasmons (GPs) and hyperbolic phonon polaritons (HPhPs) in 2D van der Waals (vdW) materials enable extreme light confinement for mid-infrared (mid-IR) photonic devices.
- However, limited propagation lengths of GPs and HPhPs restrict their practical applications.
Purpose of the Study:
- To demonstrate long-range surface polaritons (LRSPs) in 2D vdW materials with enhanced propagation lengths and group velocities.
- To explore LRSPs as a complementary approach for high-speed on-chip photonic applications in the mid-IR regime.
Main Methods:
- Fabrication of deep-subwavelength heterostructures using hexagonal boron nitride (h-BN), germanium (Ge), and gold (Au) films.
- Experimental characterization of polariton propagation distances within the heterostructure.
- Theoretical modeling to predict propagation length.
Main Results:
- Experimental demonstration of LRSPs with propagation distances exceeding 80 micrometers across an h-BN flake.
- Theoretical prediction of a remarkable propagation length of approximately 925 micrometers.
- Observation of minimal decay in propagation distances.
Conclusions:
- LRSPs in 2D vdW heterostructures offer significantly longer propagation distances and faster group velocities compared to existing polaritons.
- These LRSPs are suitable for developing polaritonic interconnects for compact mid-IR photonic systems.
- This advancement facilitates mid-IR information transport and integration with other vdW material-based photonic devices.
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