Design method for quasi-isotropic transformation materials based on inverse Laplace's equation with sliding boundaries

TL;DR

This paper introduces a novel deformation method based on inverse Laplace's equation with sliding boundaries to design quasi-isotropic transformation materials, enhancing broadband device performance and simplifying the design process.

Contribution

It develops a new approach using inverse Laplace's equation for designing quasi-isotropic transformation materials with conformal transformations, unifying design and validation.

Findings

Successfully designed a carpet cloak and waveguide with arbitrary cross sections.

The method produces smooth, quasi-conformal transformations suitable for broadband applications.

Compared to existing methods, it offers a more integrated and convenient design process.

Abstract

The deformation method of transformation optics has been demonstrated to be a useful tool, especially in designing arbitrary and nonsingular transformation materials. Recently, there are emerging demands for isotropic material parameters, arising from the broadband requirement of the designed devices. In this work, the deformation method is further developed to design quasi-isotropic/isotropic transformation materials. The variational functional of the inverse Laplace's equation is investigated and found to involve the smooth and quasi-conformal nature of coordinate transformation. Together with the sliding boundary conditions, the inverse Laplace's equation can be utilized to give transformations which are conformal or quasi-conformal, depending on functionalities of interest. Examples of designing an arbitrary carpet cloak and a waveguide with arbitrary cross sections are given to validate the proposed idea. Compared with other quasi-conformal methods based on grid generation tools, the proposed method unifies the design and validation of transformation devices, and thus is much convenient.