Topologically tuned terahertz confinement in a nonlinear photonic chip

TL;DR

This paper demonstrates topologically protected nonlinear generation and confinement of terahertz waves in a lithium niobate chip with a Su-Schrieffer-Heeger lattice, offering robust control for advanced photonic applications.

Contribution

It introduces a topologically tuned approach to confine and generate THz waves in a nonlinear photonic chip, leveraging topological protection to overcome fabrication defects.

Findings

Direct visualization of THz band structures

Robustness of topological THz waves to perturbations

Successful confinement in a wedge-shaped lattice

Abstract

Compact terahertz (THz) functional devices are greatly sought after for high-speed wireless communication, biochemical sensing, and non-destructive inspection. However, conventional devices to generate and guide THz waves are afflicted with diffraction loss and disorder due to inevitable fabrication defects. Here, based on the topological protection of electromagnetic waves, we demonstrate nonlinear generation and topologically tuned confinement of THz waves in a judiciously-patterned lithium niobate chip forming a wedge-shaped Su-Schrieffer-Heeger lattice. Experimentally measured band structures provide direct visualization of the generated THz waves in momentum space, and their robustness to chiral perturbation is also analyzed and compared between topologically trivial and nontrivial regimes. Such chip-scale control of THz waves may bring about new possibilities for THz integrated topological circuits, promising for advanced photonic applications.