End-to-end nanophotonic inverse design for imaging and polarimetry

Zin Lin,Steven G Johnson,Raphaël Pestourie,Marin Soljačić,Arka Majumdar,Charles Roques-Carmes

doi:10.1515/nanoph-2020-0579

Zin Lin, Steven G Johnson + Show 4 more

Open Access

https://doi.org/10.1515/nanoph-2020-0579

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Abstract

AbstractBy codesigning a metaoptical front end in conjunction with an image-processing back end, we demonstrate noise sensitivity and compactness substantially superior to either an optics-only or a computation-only approach, illustrated by two examples: subwavelength imaging and reconstruction of the full polarization coherence matrices of multiple light sources. Our end-to-end inverse designs couple the solution of the full Maxwell equations—exploiting all aspects of wave physics arising in subwavelength scatterers—with inverse-scattering algorithms in a single large-scale optimization involving≳104$\gtrsim {10}^{4}$degrees of freedom. The resulting structures scatter light in a way that is radically different from either a conventional lens or a random microstructure, and suppress the noise sensitivity of the inverse-scattering computation by several orders of magnitude. Incorporating the full wave physics is especially crucial for detecting spectral and polarization information that is discarded by geometric optics and scalar diffraction theory.

Highlights

Computational imaging and computer vision plays an increasingly important role in modern technology, ranging from simplest image de-noising routines to state-of-the-art object recognition, robotic vision and machine intelligence algorithms with widespread demand in defense, medical as well as emerging Internet-of-Things (IoT) industries
Our end-to-end inverse designs couple the solution of the full Maxwell equations— exploiting all aspects of wave physics arising in subwavelength scatterers—with inverse-scattering algorithms in a single large-scale optimization involving ≳104 degrees of freedom
Incorporating the full wave physics is especially crucial for detecting spectral and polarization information that is discarded by geometric optics and scalar diffraction theory

Summary

Introduction

Computational imaging and computer vision plays an increasingly important role in modern technology, ranging from simplest image de-noising routines to state-of-the-art object recognition, robotic vision and machine intelligence algorithms with widespread demand in defense, medical as well as emerging Internet-of-Things (IoT) industries. We design metaoptical structures that generate well-conditioned (noise-robust) inverse-scattering problems, while exploiting a simple Tikhonov-regularization method (Section 3) to obtain subwavelength resolution without subwavelength focusing, or to enable multidimensional information extraction from a single-shot measurement. Accomplishing this requires that the optical “inverse” design problem, involving large-scale optimization over ≈104 degrees of freedom, be coupled with the reconstruction algorithms (Section 2). The raw image v is fed into a signal-processing algorithm to approximately reconstruct u [6], in our case by a

End-to-end framework

Imaging at subwavelength resolutions

Summary and outlook