The serpentine optical waveguide: engineering the dispersion relations and the stopped light points

Area of Science:

• Photonics and Optical Engineering
• Condensed Matter Physics

Background:

• Optical waveguides are fundamental components in photonic integrated circuits.
• Controlling light propagation, particularly achieving slow light, is crucial for advanced optical signal processing and buffering.
• Existing slow-light structures often have limitations in tunability and bandwidth.

Purpose of the Study:

• To introduce and analyze a new serpentine waveguide structure for generating slow light.
• To investigate the dispersion relation, group velocity, and group velocity dispersion (GVD) of this novel structure.
• To demonstrate the tunability of the zero group velocity points within the Brillouin zone.

Main Methods:

• Analytical study using the transfer matrix method to derive dispersion relations.
• Numerical simulations employing the finite difference time domain (FDTD) method for validation.
• Investigation of the impact of coupling coefficients on the optical properties.

Main Results:

• The serpentine waveguide structure exhibits zero group velocity points at the Brillouin zone edges and within the zone.
• The position of the mid-zone zero group velocity point is tunable by adjusting the coupling coefficient between waveguide loops.
• Closed-form analytic expressions for dispersion relations and group velocity were successfully derived.

Conclusions:

• The proposed serpentine waveguide is a promising platform for creating tunable slow-light phenomena.
• The ability to tune zero group velocity points offers new possibilities for optical device design.
• This work provides a theoretical and numerical foundation for realizing advanced photonic devices based on this structure.