Direct measurement of second-order coupling in a waveguide lattice

TL;DR

This paper introduces a direct measurement method for second-order coupling in optical waveguide arrays using an integrated eigenmode interferometer, revealing that such coupling can be effectively suppressed.

Contribution

The study presents a novel measurement technique that isolates second-order coupling, providing new insights into waveguide interactions beyond nearest-neighbour effects.

Findings

Second-order coupling can be suppressed below expected exponential decay levels.

The interferometer technique isolates second-order effects from nearest-neighbour dynamics.

Results demonstrate precise control over coupling in waveguide lattices.

Abstract

We measure the next-nearest-neighbour coupling in an array of coupled optical waveguides directly via an integrated eigenmode interferometer. In contrast to light propagation experiments, the technique is insensitive to nearest-neighbour dynamics. Our results show that second-order coupling in a linear configuration can be suppressed well below the level expected from the exponential decay of the guided modes.