New Framework Optimises Topological Photonic Crystals for Silicon Light Transport

A novel theoretical framework now permits the design of the Spin-Valley Hall Phase (SVHP) in non-antiferromagnetic systems without breaking time-reversal symmetry. This development addresses a significant bottleneck in the engineering of topological photonic crystals. By leveraging the evanescent coupling between nearby resonators, the study reveals a π1(S1) topology characterised by a quantized coupling winding number.

Topological Photonic Crystals and Winding Numbers

Traditional topological phases derived from spin or pseudo-spin typically rely on specific constraints, such as spin-orbit interaction or antiferromagnetism. This dependence limits design flexibility. The new framework diverges from this by focusing on the evanescent coupling itself. Tailoring the coupling winding number enables the creation of multiple distinct phases in silicon-on-insulator designs. These include the standard SVHP, its anomalous variant, the anomalous Hall phase, and anti-helical edge states.

The mechanics are precise. The anti-helical edge states are designed independently of next-nearest coupling tuning. This separation simplifies the parameter space required for effective design. Consequently, the study suggests that these theoretical models can be realised using conventional fabrication processes. The compatibility with standard manufacturing indicates high potential for practical applications in spin-valley protected light transport and slow light guiding.

This approach prioritises versatility. By removing the requirement for magnetic components, the framework allows for more efficient integration into existing photonic circuitry. It transforms how researchers might approach the routing of light at the chip scale.