Sagnac-Loop-Reflector Fabry-Perot Lattices for Modular 1D Topological Photonics

TL;DR

This paper presents a modular silicon-photonic Fabry-Perot lattice using tunable Sagnac loop reflectors, enabling topological photonics with robust edge states and controllable lattice properties.

Contribution

It introduces a novel Sagnac-loop-reflector-based Fabry-Perot lattice platform for topological photonics with modular control and demonstrated robustness.

Findings

Simulated a 20-site lattice showing topological edge states.

Derived the dispersion relation and effective Hamiltonian.

Showed robustness against certain disorder perturbations.

Abstract

We introduce a modular silicon-photonic Fabry-Perot resonator lattice based on cascaded tunable Sagnac loop reflectors. Each SLR is controlled by a single directional-coupler cross-coupling coefficient, enabling modular control of the effective lattice hoppings. As a representative example, alternating two SLR types maps the lattice onto the Su-Schrieffer-Heeger model in the weak-coupling limit. We derive the Bloch dispersion via a transfer-matrix formulation and obtain an effective tight-binding Hamiltonian in the weak-coupling limit. S-parameter simulations of a 20-site lattice show an isolated midgap resonance with edge-localized power profiles in the topological phase, and disorder tests show robustness against symmetry-preserving hopping perturbations. Our results establish SLR-based FP lattices as a complementary platform for on-chip topological photonics.