580 California St., Suite 400
San Francisco, CA, 94104
Key research themes
1. How can transformation optics enable the design and control of invisibility cloaks, concentrators, and illusion devices across electromagnetic and elastic wave domains?
This theme encompasses the theoretical formulation and practical designs of invisibility cloaks, wave concentrators, and illusion optics devices using transformation optics principles. It spans both electromagnetic and elastic wave regimes, addressing the challenges of implementing anisotropic and inhomogeneous material parameters through coordinate transformations. The works explore how geometric mappings modify wave trajectories to achieve cloaking, field concentration, or source transformation effects. This line of research is critical to advancing stealth technologies, non-invasive sensing, and wave manipulation paradigms.
Key finding: The paper develops cylindrical elastic cloaks derived from linear geometric transforms under the Milton-Briane-Willis theory extending transformation optics to elastodynamics. The authors classify cloaks into three... Read more
Key finding: This study formulates a transformation optics-based device that compresses and expands space to not only alter the radiation pattern of a source but also virtually relocate the emission point in space. Using a linear radial... Read more
Key finding: This work proposes bilaterally functional transformation optics devices achieving simultaneous resizing and location shifting of embedded objects. Unlike prior devices with anisotropic and negative parameters, the authors... Read more
2. How can transformation optics and metamaterials be practically realized for advanced electromagnetic devices like lenses and antennas with isotropic, broadband, and low-reflection characteristics?
This theme investigates the practical fabrication and design methodologies for transformation optics-derived devices such as lenses and beam steering antennas that use isotropic graded-index materials for broadband operation and reduced complexity. Research highlights the use of 3D printing techniques, quasi-conformal transformation optics (QCTO) for material isotropy, and new fabrication methods to overcome challenges of anisotropy and inhomogeneity, aiming for real-world device integration in telecommunications, radar, and optical systems.
Key finding: The article presents a fully 3D-printed hyperbolic flat lens operating at 30 GHz fabricated using ABS dielectric filaments with varying infill percentages to achieve graded permittivity profiles predicted by transformation... Read more
Key finding: Using quasi-conformal transformation optics (QCTO), the authors design and experimentally validate an all-dielectric graded-permittivity lens fabricated by 3D polyjet printing that steers beams emitted from planar microstrip... Read more
Key finding: This work designs and experimentally demonstrates a wide-angle scanning conformal phased array antenna using an all-dielectric quasi-conformal transformation optics lens providing graded refractive index profiles. The system... Read more
Key finding: The authors design a broadband flat lens antenna using conformal transformation optics with optimized physical space to avoid refractive index singularities and sub-unity indices near boundaries. The optical path rescaling... Read more
3. How can transformation optics principles improve electromagnetic simulation efficiency and enable novel wave control devices such as compact reflectors and metasurface lenses for wireless power transfer?
This theme covers computational and applied aspects of transformation optics, including methods to enhance electromagnetic simulation efficiency through coordinate transformations enabling non-uniform discretization grids, as well as the design of compact retrodirective reflectors and metasurface lenses. By combining TO with surface impedance modulation and metamaterials, the works show how to miniaturize conventional devices while maintaining or improving performance, with specific applications in radar, communications, and wireless power transfer systems.
Key finding: This study integrates transformation optics methodology within finite-difference time-domain (FDTD) simulations to map non-uniform physical grids onto uniform numerical coordinates, enabling spatial refinement near... Read more
Key finding: The paper proposes a method to design low-profile retrodirective corner reflectors via linear coordinate transformation compressing the space occupied by classical reflectors. The transformation domain requires anisotropic... Read more
Key finding: Introducing a hybrid approach combining transformation optics and surface impedance modulation (SIM), this study designs flattened retrodirective reflectors with relaxed anisotropic material constraints. Phase gradient... Read more
Key finding: The authors present a design methodology for magnetic metasurface lenses composed of subwavelength unit cells with negative magnetic permeability but varying refractive indices. Using transformation optics, they derive unit... Read more