Tunable Terahertz Hyperbolic Metamaterial
Slabs and Super-resolving Hyperlenses
Posted on 2020-05-27 - 15:33
Terahertz optics offer the potential to image through objects that are opaque for
visible wavelengths and provide unique spectroscopic signatures for a variety of materials and
quantum processes. However, the resolution of THz images suffers from the long wavelength
of THz light compared to visible. Hyperbolic metamaterials provide a possible solution
through the creation of superresolving lenses and offer greater flexibility in effective
refractive index than can be provided by natural materials. Most hyperbolic metamaterials
function in a narrow bandwidth due to their resonant nature. In search of a broadband
material, we simulate a temperature-tunable hyperbolic metamaterial composed of a
multilayer stack of alternating layers of high-density polyethylene (HDPE) and indium
antimonide (InSb). At a single temperature, negative effective medium permittivity is found
over a small bandwidth of 0.09 THz, but by tuning over a 40°C temperature range, the
bandwidth is increased dramatically to 1.0 THz. Furthermore, we compute the transmission
and negative refraction through the multilayer stack and simulate the imaging properties of
curved hyperlens stacks using slits as test objects, achieving resolutions as small as 20 μm at
130 μm wavelength, far below the half-wavelength diffraction limit.