Spiral hyperlens with enhancements of image resolution and magnification

Abstract

A subwavelength spiral hyperlens that is able to image beyond the diffraction limit is studied. The spiral hyperlens is made from an anisotropic metamaterial with a hyperbolic dispersion relation in which the evanescent wave is converted into a propagating wave. Therefore, the propagating wave can be processed by conventional optical systems outside of the spiral hyperlens. The possibility of using a cylindrical hyperlens for overcoming the diffraction limit has been proven analytically and experimentally. In this study, we designed two types of spiral hyperlenses composed of a spiral periodic stack of silver and alumina multilayers. A spiral hyperlens utilizes the spiral geometry to magnify the objects. In comparison with a cylindrical hyperlens, a spiral hyperlens has improved performance in terms of higher image resolution and better image magnifications. Numerical simulations illustrate that the far-field imaging resolution of cylindrical spiral hyperlens is no greater than 110 nm at 365 nm working wavelength.

Keywords:

• Hyperlens
• spiral hyperlens
• diffraction limit
• far-field imaging
• metamaterial
• nano-optics

Acknowledgement

The author would especially like to thank to Prof. Chen for his useful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work is partially supported by prof. Lien-Wen Chen and prof. I-Ling Chang from National Cheng Kung University.

Additional information

Funding

This work is partially supported by Prof. Lien-Wen Chen and Prof. I-Ling Chang from National Cheng Kung University.