3D Luneburg Lens Research Articles

3D underwater acoustic Luneburg lens based on gradient face-centered-cubic phononic crystals

A Luneburg lens is a gradient refractive index lens that can focus plane waves on a point at the perimeter without aberration. Three-dimensional (3D) Luneburg lens for airborne sound has been well investigated in recent years. However, constructing a 3D Luneburg lens for underwater sound is a challenging task due to the difficulties in the designing and fabricating of the desired isotropic underwater acoustic materials. This work presents the practical implementation of a 3D Luneburg lens for underwater sound. Such a 3D Luneburg lens is designed based on 3D gradient face-centered-cubic phononic crystals, which have quasi-isotropic refractive index patterns and can be fabricated with photosensitive resin by 3D printing. The experimental results show that the lens can realize the omnidirectional imaging of underwater sound from 30 to 38 kHz. This 3D underwater acoustic Luneburg lens may prompt the potential applications in underwater acoustic wide-angle retroreflectors, sonars, and biomedical imaging devices.

An all-dielectric 3D Luneburg lens constructed by common-vertex coaxial circular cones

An all-dielectric broadband 3D Luneburg lens has been designed and manufactured in our study, which is constructed by common-vertex coaxial circular cones. A prototype of the lens is fabricated using 3D printing technology. The far field of the, present lens is highly directive, incident waves are focused with highly concentration, and its operating frequency spans from 5 GHz to 20 GHz. It is also found that two highly directional beams are generated while two independent converged sources feed simultaneously at the edge of the lens. The intersection angle with the center of the lens is 90°, which indicates that the lens is an efficient double input-double output device.

Three‐dimensional Luneburg lens at optical frequencies (Laser Photonics Rev. 10(4)/2016)

A Luneburg lens is a fascinating gradient refractive index lens that can focus parallel light on a perfect point without aberration in geometrical optics. A three-dimensional (3D) Luneburg lens operating at optical frequencies is proposed by Zhao et al. as a first experimental demonstration. This gradient refractive index lens is realized by laser direct writing, and the refractive profile of simple cubic metamaterials is tailored by the fill factor. Experimentally, 3D ideal focus performance has been observed via near-field optical microscopy, which is a direct experimental evidence for 3D Luneburg lens to achieve the ideal focus of mid-IR light. (Picture: Yuan-Yuan Zhao et al., 10.1002/lpor.201600051 pp. 665–672, in this issue)

Three‐dimensional Luneburg lens at optical frequencies

AbstractA Luneburg lens is a fascinating gradient refractive index (GRIN) lens that can focus parallel light on a perfect point without aberration in geometrical optics. Constructing a three‐dimensional (3D) Luneburg lens at optical frequencies is a challenging task due to the difficulty of fabricating the desired GRIN materials. Here, we present the practical implementation of a 3D Luneburg lens at optical frequencies. Such a 3D Luneburg lens is designed with GRIN 3D simple cubic metamaterial structures, and fabricated with dielectric metamaterials by femtosecond laser direct writing in the commercial negative‐photoresist IP‐L. Simulated and experimental results exhibit an interesting 3D ideal focus for the infrared light. The protocol for developing the 3D Luneburg lens with ideal focus would prompt the potential applications in integrated light‐coupled devices and lab‐on‐chip integrated biological sensors based on infrared light. image