Near-Field Excited Archimedean-like Tiling Patterns in Phonon-Polaritonic Crystals

Area of Science:

• Condensed Matter Physics
• Photonics
• Materials Science

Background:

• Phonon-polaritons (PhPs) result from strong photon-optical phonon coupling, enabling sub-diffraction light confinement for various applications.
• Exploration of hyperbolic materials integrated into periodic dielectric substrates for PhPs remains limited.
• Hyperbolic hexagonal boron nitride (hBN) offers unique optical properties for manipulating light.

Purpose of the Study:

• To investigate novel phonon-polaritonic crystals (PPCs) by incorporating hyperbolic hBN into silicon-based photonic crystals.
• To explore the potential of these PPCs for sub-diffraction light confinement and applications in the mid-infrared range.
• To demonstrate the tunability of PPC band structures and confirm the interaction of hBN with photonic crystals.

Main Methods:

• Utilized scattering-type scanning near-field optical microscopy (s-SNOM) with near-field excitation to resolve local field distributions.
• Employed numerical simulations to analyze and demonstrate the tunability of PPC band structures.
• Conducted scattering-type nano infrared (nanoIR) spectroscopy to confirm hBN-photonic crystal interactions.

Main Results:

• Resolved two distinct repetitive local field distribution patterns: dipolar-like distributions and dispersive PhP interference patterns.
• Demonstrated tunability of PPC band structures by varying the thickness of hyperbolic hBN layers.
• Confirmed the strong interaction between hBN and the silicon photonic crystal via nanoIR spectroscopy.

Conclusions:

• Introduced novel hBN-based PPCs with Archimedean-like tiling, exhibiting unique phonon-polaritonic behaviors.
• These PPCs offer a platform for fabricating essential sub-diffraction optical components for mid-infrared applications.
• The findings pave the way for advanced photonic devices leveraging hyperbolic materials and phonon-polaritons.