Abstract

We present an optimization framework based on Lagrange duality and the scattering $\mathbb{T}$-operator of electromagnetism to construct limits on the possible features that may be imparted to a collection of output fields from a collection of given input fields, i.e., constraints on achievable optical transformations and the characteristics of structured materials as communication channels. Implications of these bounds on the performance of representative optical devices having multiwavelength or multiport functionalities are examined in the context of electromagnetic shielding, focusing, near-field resolution, and linear math kernels.

Highlights

  • As undoubtedly surmised since long before Shannon’s pioneering work on communication [1] or Kirchhoff’s investigation of the laws governing thermal radiation [2], physics dictates that there are meaningful limits on how any measurable quantity may be transferred between a sender and receiver that apply largely independent of the precise details by which transmission is realized

  • Linear operations are to be inferred by juxtaposition, e.g., E|M|E = dydxE∗(y, ω) · M(y, x, ω) · E(x, ω), where “·” is the vector inner product at a spatial point, the ∗ superscript denotes complex conjugation, and M is a “dyadic” function of the spatial coordinates x and y

  • All stated relations hold in greater generality, for simplicity in analysis and discussion, we will suppose that all scattering potentials under consideration can be described by a linear electric susceptibility that does not mix field components from distinct spatial points

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Summary

INTRODUCTION

As undoubtedly surmised since long before Shannon’s pioneering work on communication [1] or Kirchhoff’s investigation of the laws governing thermal radiation [2], physics dictates that there are meaningful limits on how any measurable quantity may be transferred between a sender and receiver (collectively registers) that apply largely independent of the precise details by which transmission is realized. Beyond well-established considerations such as the need to conserve power in passive systems and the classical diffraction limit of vacuum [28], such contextspecific limits are typically unknown [29] It is seldom clear what level of possible performance improvement should be sensibly supposed, even to within multiple orders of magnitude [30,31,32]. During this brief overview, two innovations for handling generic input-output formulations are introduced: a further generalization on the variety of operator constraints that can be imposed based on the definition of the T -operator, beyond the possibility of local clusters examined in Refs. IV, is strongly tied to the ability of the formulation to properly enforce that every transformation is mediated by single (unique) material scattering geometry

CHANNEL LIMITS IN PRIOR ART
Notation and assumptions
Scattering perspective
Optimization perspective
Volume integral constraints
Handling multiple transformation channels
APPLICATIONS
Objective
Results
SUMMARY DISCUSSION
Off-origin dipole spherical wave expansions
Computation for two-dimensional examples
Full Text
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