Non-PT-symmetric two-layer cylindrical waveguide for exceptional-point-enhanced optical devices

Area of Science:

• Optics and Photonics
• Waveguide Theory
• Materials Science

Background:

• Exceptional points (EPs) are unique spectral degeneracies in non-Hermitian systems.
• Cylindrical waveguides are fundamental structures in optical and microwave applications.
• Dielectric materials with varying optical properties are crucial for waveguide design.

Purpose of the Study:

• To investigate the formation and properties of exceptional points in a two-layer cylindrical waveguide.
• To explore the potential for enhanced sensitivity in such structures.
• To assess the feasibility of developing novel optical waveguide devices.

Main Methods:

• Numerical analysis of a two-layer cylindrical waveguide model.
• Tuning of structural parameters: core-to-total radius ratio and core refractive index.
• Calculation of complex effective indices for waveguide modes.
• Analysis of sensitivity to variations in the shell layer's refractive index.

Main Results:

• Exceptional points were successfully formed by tuning waveguide parameters.
• Enhanced sensitivity of waveguide mode effective index to refractive index variations was observed at EPs.
• Greater sensitivity enhancement was achieved with smaller perturbations.

Conclusions:

• Exceptional points can be engineered in two-layer cylindrical waveguides.
• These structures exhibit enhanced sensitivity, particularly at EPs.
• Potential applications include chip-scale optical modulators, switches, and sensors.