Dear Colleagues,

Transformation optics (TO) has revolutionized our understanding of electromagnetism, endowing the optical design toolbox with an unprecedented flexibility and intuitive character. Based on a geometrical formalism connected to general relativity, this technique allows us to find the medium properties required to mold the spatiotemporal distribution of electromagnetic fields in almost any desired manner. Conversely, TO provides a shortcut to easily obtain analytical solutions to Maxwell’s equations in complicated scenarios, such as those involving singular plasmonic structures.

Usually, transformation media demand exotic properties whose implementation relies on artificially structured materials (metamaterials and metasurfaces) with subwavelength features. At optical frequencies, this requires the use of nanophotonic technology, which has proven to be a fertile ground for the demonstration of a variety of TO-related effects, from invisibility cloaking to optical analogues of relativistic phenomena. In turn, TO constitutes a powerful tool for the design of novel nanophotonic devices outperforming their classical counterparts. 

Throughout the last few years, the extension of the original TO theory to curved geometries, more general transformation schemes (including spacetime, nonlocal, complex, nontensorial, and supersymmetric transformations), and more general media (e.g., hyperbolic, epsilon-near-zero, and PT-symmetric media), has added new knowledge and achievable effects to the TO repertoire. Likewise, novel techniques and materials with improved properties have enhanced the potential capabilities of nanophotonic technology.

With this updated arena in mind, the aim of the present Special Issue is to attract novel research at the intersection of transformation optics and nanophotonics, from theoretical insight and technological advances beyond the current state of the art, to the use of nanophotonics as a proof-of-concept platform for TO-related phenomena.

Dr. Carlos García-Meca
Guest Editor

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• transformation optics
• nanophotonics
• photonic integrated circuits
• metamaterials
• metasurfaces
• plasmonics
• invisibility cloaking
• supersymmetry
• PT symmetry
• analogue gravity