On-chip multi-timescale spatiotemporal optical synchronization

TL;DR

This paper demonstrates on-chip multi-timescale optical mode-locking using topological photonics, enabling nested synchronized states with distinct fast and slow timescales, advancing nonlinear optics and integrated photonic technologies.

Contribution

It introduces a novel multi-timescale mode-locking mechanism on a chip using topological photonics, expanding the nonlinear mode-locking toolbox with independently tunable timescales.

Findings

Successful demonstration of multi-timescale mode-locking in a 2D lattice of silicon nitride resonators.

Observation of quadratic pump noise distribution consistent with mode-locking theory.

Identification of edge-confined mode-locked states distinct from bulk and single-ring counterparts.

Abstract

Mode-locking mechanisms are key resources in nonlinear optical phenomena, such as micro-ring solitonic states, and have transformed metrology, precision spectroscopy, and optical communication. However, despite significant efforts, mode-locking has not been demonstrated in the independently tunable multi-timescale regime. Here, we vastly expand the nonlinear mode-locking toolbox into multi-timescale synchronization on a chip. We use topological photonics to engineer a 2D lattice of hundreds of coupled silicon nitride ring resonators capable of hosting nested mode-locked states with a fast (near 1 THz) single-ring and a slow (near 3 GHz) topological super-ring timescales. We demonstrate signatures of multi-timescale mode-locking including quadratic distribution of the pump noise with the two-time azimuthal mode dimensions, as expected by mode-locking theory. Our observations are further corroborated by direct signatures of the near-transform-limit repetition beats and the formation of the temporal pattern on the slow timescale. Moreover, we show that these exotic properties of edge-confined mode-locked states are in sharp contrast to bulk and single-ring counterparts and establish a clear pathway for their identification. Our unprecedented demonstration of mode-locking in topological combs unlocks the implementation of lattice-scale synchronization and independently tunable multi-timescale mode-locking phenomena, also the exploration of the fundamental nonlinearity-topology interplay on a chip.