Phase-multiplexed optical computing: Reconfiguring a multi-task diffractive optical processor using illumination phase diversity

TL;DR

This paper introduces a reconfigurable monochrome diffractive optical network that uses illumination phase multiplexing to perform multiple complex-valued linear transformations, enabling dynamic multi-task optical computing with high accuracy.

Contribution

The work presents a novel phase-multiplexed diffractive network architecture that can implement a large set of transformations using phase keys, reducing errors compared to wavelength multiplexing.

Findings

Implemented 512 complex transformations with negligible error

Demonstrated dynamic reconfiguration via phase keys

Achieved lower transformation errors than wavelength-multiplexed systems

Abstract

We report a monochrome multi-task diffractive network architecture that leverages illumination phase multiplexing to dynamically reconfigure its output function and accurately implement a large group of complex-valued linear transformations between an input and output aperture. Each member of the desired group of T unique transformations is encoded and addressed with a distinct 2D illumination phase profile, termed "phase key", which illuminates the input aperture, activating the corresponding transformation at the output field-of-view. A common diffractive optical network, optimized with T phase keys, demultiplexes these encoded inputs and accurately executes any of the T distinct linear transformations at its output. We demonstrate that a diffractive network composed of N = 2 x T x Ni x No optimized diffractive features can realize T distinct complex-valued linear transformations, accurately executed for any complex field at the input aperture, where Ni and No refer to the input/output pixels, respectively. In our proof-of-concept numerical analysis, T = 512 complex-valued transformations are implemented by the same monochrome diffractive network with negligible error using illumination phase diversity. Compared with wavelength-multiplexed diffractive systems, phase-multiplexing architecture significantly lowers the transformation errors, potentially enabling larger-scale optical transformations to be implemented through a monochrome processor. Phase-multiplexed multi-task diffractive networks would enhance the capabilities of optical computing and machine-vision systems.