Transformation optics

About: Transformation optics is a research topic. Over the lifetime, 2687 publications have been published within this topic receiving 102378 citations.

Transforming two-dimensional guided light using nonmagnetic metamaterial waveguides

Abstract: Almost a decade ago, transformation optics established a geometrical perspective to describe the interaction of light with structured matter, enhancing our understanding and control of light. However, despite their huge technological relevance in applications such as optical circuitry, optical detection, and actuation, guided electromagnetic waves along dielectric waveguides have not yet benefited from the flexibility and conceptual simplicity of transformation optics. Indeed, transformation optics inherently imposes metamaterials not only inside the waveguide's core but also in the surrounding substrate and cladding. Here we restore the two-dimensional nature of guided electromagnetic waves by introducing a thickness variation on an anisotropic dielectric core according to alternative two-dimensional equivalence relations. Our waveguides require metamaterials only inside the core with the additional advantage that the metamaterials need not be magnetic and, hence, our purely dielectric waveguides are low loss. We verify the versatility of our theory with full wave simulations of three crucial functionalities: beam bending, beam splitting, and lensing. Our method opens up the toolbox of transformation optics to a plethora of waveguide-based devices.

Critical opalescence in hyperbolic metamaterials

Abstract: Hyperbolic metamaterials in which the dielectric component exhibits critical opalescence have been considered. It appears that fluctuations of the effective refractive index in these materials are strongly enhanced and so 'virtual electromagnetic black holes' may appear as a result of these fluctuations. Therefore, the behaviour of 'optical space' inside hyperbolic metamaterials looks somewhat similar to the behaviour of real physical space-time on the Planck scale.

Compact optical waveguide coupler using homogeneous uniaxial medium

Abstract: We introduce the homogeneous transformation optics method into the design of a compact two dimensional (2D) beam coupler. Only homogeneous, nonmagnetic dielectric materials are required, and the fabrication process will thus be simplified. As designed, the coupler can well preserve the beam profile, with the volume significantly smaller than traditional non-transformed ones. It also excels in reducing reflectance and thus significantly increases the transmission efficiency. The coupler, with potential application in micro- and nanoscale photonics, can be applied into the design of an optoelectronic circuit that strongly requires compact volume. It can also be used as a compact squeezer or expander to adjust the radius of an optical beam, to couple with other photonic and/or electronic devices.

Errata to “Full-Vector Finite-Element Beam Propagation Method for Helicoidal Waveguides and its Application to Twisted Photonic Crystal Fibers”

Abstract: A full-vector beam propagation method based on a finite-element scheme for a helicoidal system is developed. The permittivity and permeability tensors of a straight waveguide are replaced with equivalent ones for a helicoidal system, obtained by transformation optics. A cylindrical, perfectly matched layer is implemented for the absorbing boundary condition. To treat wide-angle beam propagation, a second-order differentiation term with respect to the propagation direction is directly discretized without using a conventional Pade approximation. The transmission spectra of twisted photonic crystal fibers are thoroughly investigated, and it is found that the diameters of the air holes greatly affect the spectra. The calculated results are in good agreement with the recently reported measured results, showing the validity and usefulness of the method developed here.