Slow light mediated by mode topological transitions in hyperbolic waveguides

Area of Science:

• Photonics and optical physics.
• Condensed matter physics.

Background:

• Hyperbolic waveguides exhibit unique optical properties due to their material composition and structure.
• Topological transitions in optical systems can lead to novel phenomena like slow light.

Purpose of the Study:

• To investigate the link between topological transitions in the dispersion diagram of hyperbolic waveguides and the emergence of slow light.
• To analyze the role of film thickness in mediating these topological transitions.

Main Methods:

• Analysis of dispersion diagrams in symmetric planar hyperbolic waveguide structures with type II films.
• Identification of mode branch coalescences and transformations, including saddle and branch points.

Main Results:

• Slow light in hyperbolic waveguides is directly linked to topological transitions in the dispersion diagram.
• Transitions occur in type II films with optical axis parallel to interfaces, mediated by coalescing elliptical and hyperbolic mode branches.
• Saddle points transform into branch points, creating slow light across a wide thickness range and introducing ghost wave branches.

Conclusions:

• Topological transitions in hyperbolic waveguide dispersion are a key mechanism for achieving slow light.
• The film thickness is a critical parameter controlling these transitions and the resulting optical properties.
• The findings offer new avenues for designing advanced photonic devices utilizing slow light.