A 3D terahertz gradient-refractive index lens designed by transformation optics is achieved by fabricating “woodpile” structures with varying dimensions of subwavelength dielectric unit cells using the projection microstereolithography technique. Both simulation and experimental investigations confirm that the lens delivers an imaging resolution very close to the diffraction limit over a frequency range from 0.4 to 0.6 THz.
The new lens could be used for biomedical research and security imaging. “Terahertz is somewhat of a gap between microwaves and infrared,” said NW University’s Cheng Sun. “People are trying to fill in this gap because this spectrum carries a lot of information...
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