T-shaped topological polarization beam splitter based on a synthetic dimension

Area of Science:

• Condensed Matter Physics
• Photonics
• Materials Science

Background:

• Topological photonics offers novel ways to control light propagation.
• Photonic crystals (PCs) provide a versatile platform for manipulating electromagnetic waves.
• Achieving common bandgaps for different polarizations in PCs is challenging.

Purpose of the Study:

• To propose a 2D photonic crystal (PC) supporting common bandgaps (CBGs) for both TM and TE polarizations.
• To investigate the properties of topological edge states (TESs) in the parity-inversion bandgap.
• To design and simulate a topological polarization beam splitter (TPBS) based on these TESs.

Main Methods:

• Utilizing the Jackiw-Rebbi theory to identify topological helical edge states.
• Employing translation parameters as a synthetic dimension to study TES evolution.
• Performing finite element method (FEM) simulations to verify the TPBS performance.

Main Results:

• A 2D PC with a CBG for TM and TE polarizations was successfully designed.
• Pseudospin-locked unidirectional propagation and backscattering immunity of dual-polarization TESs were demonstrated.
• An efficient T-shaped TPBS capable of separating dual-polarization TESs was designed and simulated.

Conclusions:

• The proposed 2D PC offers a robust platform for dual-polarization topological states.
• The developed TPBS demonstrates effective separation of polarized light, advancing integrated photonics.
• This work presents a new approach for designing TPBS devices, benefiting optical communication systems.