Achieving sub-wavelength imaging through a flat hyperlens in a modified anodic aluminum oxide template

Prism-shaped hyperlens for subwavelength focusing of light

Subwavelength focusing of light is on-demand for overcoming the diffraction limit of light for applications such as photolithography. A prism-shaped hyperlens capable of focusing incident light to a subwavelength scale is proposed. The lens lifts the complexity of previous structures and achieves a spot size of about λ₀/4 at the free-space wavelength λ₀=365nm. Another feature of the proposed lens is that it consists of planar input and output ports, which have been a design challenge for focusing lenses in recent years.

Achieving broad absorption band and high incident angles by stochastically-distributed oblique-flat-sheet metamaterial perfect absorbers

In this work, we integrated a periodic seed layer and oblique deposition method to fabricate a stochastically-distributed oblique-flat-sheet metamaterial perfect absorber (MPA). Such design could increase its absorption bandwidth and tolerance to high angle-incidence due to the fact that various oblique flat sheets offer different resonance conditions while even a single oblique flat sheet could provide different optical paths for resonance. On the other hand, a seed layer could reduce uncertainty regarding to direct oblique deposition and provide abilities to manipulate the bandwidth of the MPA. We also setup a simulation model in the aids of Visual Basic Application and examined the absorption behavior of the MPA under TM and TE oblique incidence that could achieve high absorbance under 80° and 60° incidence, respectively. Finally, in measurement, the fabricated sample owns 65% absorbance within 80-250 THz and over 90% absorbance within 250-320 THz at x-polarization normal incidence; as for the y-polarization normal incidence, we could achieve overall 70% absorbance within 80-300 THz. The measured results reveal similar tendency compared to the simulated ones.

Far field superlensing inside biological media through a nanorod lens using spatiotemporal information

Far field superlensing of light has generated great attention in optical focusing and imaging applications. The capability of metamaterials to convert evanescent waves to propagative waves has led to numerous proposals in this regard. The common drawback of these approaches is their poor performance inside strongly scattering media like biological samples. Here, we use a metamaterial structure made out of aluminum nanorods in conjunction with time-reversal technique to exploit all temporal and spatial degrees of freedom for superlensing. Using broadband optics, we numerically show that this structure can perform focusing inside biological tissues with a resolution of λ/10. Moreover, for the imaging scheme we propose the entropy criterion for the image reconstruction step to reduce the number of required optical transducers. We propose an imaging scenario to reconstruct the spreading pattern of a diffusive material inside a tissue. In this way super-resolution images are obtained.

Numerical Investigation on a Hyperlens with a Large Radius Inner-Surface for Super-Resolution Imaging

Hyperlensing devices have drawn great attention in recent years due to their ability to amplify the subwavelength image of objects with more detail and information. In this work, a hyperlens with a radian inner surface is designed and demonstrated. The proposed hyperlens is capable of imaging different types of sub-wavelength objects efficiently. Plasmonic resonant cavity is also employed in order to achieve a super-resolution imaging effect. Different objects are investigated to test the performance of the proposed hyperlens. As expected, our hyperlens shows better tolerance than the conventional hyperlensing designs and can achieve imaging resolution down to 60 nm for different types of objects.