All-optical mode unscrambling on a silicon photonic chip

TL;DR

This paper demonstrates an all-optical, self-configuring silicon photonic chip that unscrambles mixed optical beams, enabling the recovery of multiple high-speed data channels without manual reconfiguration.

Contribution

We introduce a silicon photonic mesh that automatically unscrambles and resets itself to recover multiple optical signals in a scattering environment.

Findings

Successfully unscrambled four 10 Gbit/s channels with -20dB cross-talk

The mesh self-configures and resets without turning off the beams

Demonstrated robustness against significant perturbations

Abstract

Propagation of light beams through scattering or multimode systems may lead to randomization of the spatial coherence of the light. Although information is not lost, its recovery requires a coherent interferometric reconstruction of the original signals, which have been scrambled into the modes of the scattering system. Here, we show that we can automatically unscramble four optical beams that have been arbitrarily mixed in a multimode waveguide, undoing the scattering and mixing between the spatial modes through a mesh of silicon photonics Mach-Zehnder interferometers. Using embedded transparent detectors and a progressive tuning algorithm, the mesh self-configures automatically and reset itself after significantly perturbing the mixing, without turning off the beams. We demonstrate the recovery of four separate 10 Gbits/s information channels, with residual cross-talk between beams of -20dB. This principle of self-configuring and self-resetting in optical systems should be applicable in a wide range of optical applications.