Enhanced displacements in reflected beams at hyperbolic metamaterials

Area of Science:

• Optics and Photonics
• Metamaterials Science
• Condensed Matter Physics

Background:

• The Goos-Hänchen (G-H) shift describes the lateral displacement of a light beam upon reflection.
• Hyperbolic multilayer metamaterials (HMMs) exhibit unique anisotropic optical properties.
• Understanding light-matter interactions in nanostructured materials is crucial for optical device development.

Purpose of the Study:

• To investigate the Goos-Hänchen (G-H) shift of a Gaussian beam reflected from an Ag/TiO2 HMM.
• To explore the underlying physics, specifically the role of Brewster modes, in enhancing the G-H shift.
• To examine related phenomena like the Imbert-Fedorov shift and the spin Hall effect of light in HMMs.

Main Methods:

• Modeling the Ag/TiO2 HMM using effective medium theory to obtain anisotropic dielectric functions.
• Analyzing the reflection of a Gaussian beam and calculating the resulting G-H shifts.
• Investigating the frequency-dependent line shape of Brewster modes and their relation to G-H shift characteristics.

Main Results:

• Observed significantly large G-H shifts on the HMM surface, reaching up to 40 µm, exceeding those on conventional materials.
• Demonstrated that the enhancement is attributed to the excitation of Brewster modes within the HMM.
• Quantified the relationship between the G-H shift's half-width at half-maximum and the imaginary part of the Brewster mode's complex frequency.
• Showcased a more pronounced spin Hall effect of light on the HMM slab compared to metallic surfaces.

Conclusions:

• Thin HMM slabs can dramatically enhance lateral optical displacements, including G-H and spin Hall effects.
• The excitation of Brewster modes is key to achieving these large optical shifts in HMMs.
• These enhanced effects present significant opportunities for the development of novel optical devices and applications.