3d Printed Lattices With Spatially Variant Self-Collimation

Abstract

Abstract-In this work, results are given for controlling waves arbitrarily inside a lattice with spatially variant self-collimation. To demonstrate the concept, an unguided beam was made to flow around a 90 • bend without scattering due to the bend or the spatial variance. Control of the field was achieved by spatially varying the orientation of the unit cells throughout a self-collimating photonic crystal, but in a manner that almost completely eliminated deformations to the size and shape of the unit cells. The device was all-dielectric, monolithic, and made from an ordinary dielectric with low relative permittivity (ε r = 2.45). It was manufactured by fused deposition modeling, a form of 3D printing, and its performance confirmed experimentally at around 15 GHz.

Spatially variant periodic structures in electromagnetics

“…No coordinate transform was needed and TO was circumvented in this manner. The first demonstration of a self-collimating SVPC was at microwave frequencies [56]. This device, shown in figure 2a, operated at around 15 GHz and flowed an unguided beam around a sharp 90 • bend.…”

Rapid Prototyping across the Spectrum: RF to Optical 3D Electromagnetic Structures

“…Ideally, EBG devices are 3D periodic arrays of geometric structures that prevent the propagation of EM waves for a given frequency band at all incident angles independent of polarization. In practice, however, partial bandgaps are observed which cover limited incident angles [16].…”

“…Prototyping processes can be classified into two classes: (i) Subtractive manufacturing: used in traditional fabrication and involves removal of material by methods such as drilling on a macroscale and lithography on a micro/nano scale; (ii) Additive manufacturing: newer technology where a 3D object can be made based on a predefined digital model [24,60]. Examples include 3D printing on a macro-scale [16,57] and ink-jet deposition of nanoscale structures [31,56].…”

Optical generation of a spatially variant two-dimensional lattice structure by using a phase only spatial light modulator

“…As an example, we take a spatially varying square lattice which changes in the lattice orientation parameter as per the azimuthal angle. This lattice is important as it has been shown to guide light through a 90° bend 4,16 by self-collimation phenomena 19 and could be a very useful photonic element. To understand the phase mask synthesis process, we start with the case of a multiple beam interference wave-field where all the beams are spread symmetrically along the surface of a cone making same 3 tilt angle with the normal.…”