研究目的
To demonstrate the use of attenuated total re?ectance (ATR) micro-spectroscopy for launching and measuring hyperbolic polaritons in hexagonal boron nitride (hBN) and to compare the optical properties of small-scale materials prepared by different techniques.
研究成果
ATR micro-spectroscopy is an effective method for launching and probing hyperbolic polaritons and dielectric resonances in 2D materials like hBN. It allows for quick, high-throughput measurements across a broad spectral range, enabling the comparison of materials prepared by different techniques. The method can distinguish materials with different isotopic purities and thicknesses, offering a simple approach to estimating damping constants in hyperbolic thin films.
研究不足
The technique is limited by the single-incident angle, making it difficult to systematically plot out the dispersion curve for a given flake. Additionally, the broad spectral range, while flexible, may not provide the detailed angle-resolved information available with other methods.
1：Experimental Design and Method Selection:
The study utilized ATR micro-spectroscopy in a Kretschmann–Raether configuration to launch hyperbolic polaritons in hBN. The approach involved using a germanium prism to provide high in-plane momentum for coupling into polariton modes.
2：Sample Selection and Data Sources:
Samples included hBN flakes with different isotopic enrichments and thicknesses, exfoliated onto a SiO2 layer on silicon. Thickness was measured using atomic force microscopy (AFM).
3：List of Experimental Equipment and Materials:
A Bruker Hyperion 2000 IR microscope coupled to a Fourier-transform IR spectrometer (Bruker Vertex 70V) with a liquid-nitrogen-cooled HgCdTe (MCT) detector and a SiC-globar source. A germanium wire grid polarizer was used for polarization control.
4：Experimental Procedures and Operational Workflow:
The sample was brought into contact with the prism mounted on the ATR microscope objective, and spectra were collected using both unpolarized and polarized IR light. The prism was cleaned with isopropyl alcohol after each measurement.
5：Data Analysis Methods:
Numerical simulations using transfer matrix and finite element methods were performed to compare with experimental data and confirm the presence of hyperbolic modes.
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