Title: Three dimensional Terahertz trasnformation optics

The recent developments of transformation optics and engineering metamateials have inspired a new generation of novel optical components in various areas. Compared to the optical and the microwave range, imaging at Tera-Hertz (THz) frequencies is still at an early stage of development due mostly to the great paucity of high performance modulator lens. In this talk, we report a systematics study in developing a three dimensional (3D) aberrations-less metamaterials lens through an integrated approach among theoretical design, numerical simulation, integrated 3D fabrication, and experimental characterization. Specifically, we applied transformation optics to “compress” the Luneburg Lens´ spherical imaging surface into a planar one but meanwhile, maintaining its remarkable focusing properties, such as aberration-less imaging characteristics over a wide collecting angle. A series of simulations are performed to validate the design of the flattened Luneburg lens. Non-resonant metamaterials are chosen to realize the 3D Luneburg lens and the index variation can be achieved by fabricating “woodpile” structures with varying the dimension of the sub-wavelength dielectric structure. Fabricating Luneburg lenses that are optically large in all three dimensions is demonstrated using micro-stereo-lithography system. Finally, transmission terahertz time-domain spectroscopy (THz-TDS) is employed to characterize the performance of Luneburg lens.