Learning Diffractive Optical Communication Around Arbitrary Opaque Occlusions

TL;DR

This paper introduces a novel optical communication method that uses deep learning to transmit information around opaque obstacles by combining neural network encoding with a passive diffractive optical decoder, validated experimentally in terahertz frequencies.

Contribution

It presents the first demonstration of passing optical information around arbitrary opaque occlusions using a jointly trained neural network encoder and a passive diffractive optical decoder.

Findings

Successful communication around arbitrary occlusions in simulations

Experimental validation in terahertz spectrum with 3D-printed decoder

Encoder retraining adapts to changing occlusion shapes without physical modifications

Abstract

Free-space optical systems are emerging for high data rate communication and transfer of information in indoor and outdoor settings. However, free-space optical communication becomes challenging when an occlusion blocks the light path. Here, we demonstrate, for the first time, a direct communication scheme, passing optical information around a fully opaque, arbitrarily shaped obstacle that partially or entirely occludes the transmitter's field-of-view. In this scheme, an electronic neural network encoder and a diffractive optical network decoder are jointly trained using deep learning to transfer the optical information or message of interest around the opaque occlusion of an arbitrary shape. The diffractive decoder comprises successive spatially-engineered passive surfaces that process optical information through light-matter interactions. Following its training, the encoder-decoder pair can communicate any arbitrary optical information around opaque occlusions, where information decoding occurs at the speed of light propagation. For occlusions that change their size and/or shape as a function of time, the encoder neural network can be retrained to successfully communicate with the existing diffractive decoder, without changing the physical layer(s) already deployed. We also validate this framework experimentally in the terahertz spectrum using a 3D-printed diffractive decoder to communicate around a fully opaque occlusion. Scalable for operation in any wavelength regime, this scheme could be particularly useful in emerging high data-rate free-space communication systems.