The design and simulation of a dielectric lens for beam deflection in the terahertz range is presented. The device consists of a lattice of sub-wavelength holes in a rectangular dielectric slab, and by varying the radii of the holes with respect to position, a gradient index (GRIN) lens can be realised. Beam deflection is achieved by giving the refractive index a ramp-like characteristic. The lens has a flat-profile, and is likely to be more compact than lenses based on geometric optics. A Fresnel lens-like design is used to expand the lens aperture. Additionally, this lens is expected to have lower loss, higher bandwidth, and be less sensitive to polarisation than similar lenses constructed from resonant metamaterials.
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