Abstract
Perfect lenses, superlenses and time-reversal mirrors can support and spatially separate evanescent waves, which is the basis for detecting subwavelength information in the far field. However, the inherent limitations of these methods have prevented the development of systems to dynamically distinguish subdiffraction-limited signals. Utilizing the physical merits of spoof surface plasmon polaritons (SPPs), we demonstrate that subdiffraction-limited signals can be transmitted on planar integrated SPP channels with low loss, low channel interference, and high gain and can be radiated with a very low environmental sensitivity. Furthermore, we show how deep subdiffraction-limited signals that are spatially coupled can be distinguished after line-of-sight wireless transmission. For a visualized demonstration, we realize the high-quality wireless communication of two movies on subwavelength channels over the line of sight in real time using our plasmonic scheme, showing significant advantages over the conventional methods.
Highlights
Distinguishing two or more signals with subwavelength separation has accelerated research in many fields, including photonics, super-resolution imaging, and dense communication, which are always hampered by the socalled diffraction limit
We demonstrate that a series of inherent channel interference problems due to repeated coupling–gain–coupling processes in adjacent subdiffraction-limit channels can be solved by employing the unprecedented field confinement associated with the spoof surface plasmon polaritons (SPPs) modes
In the experimental set-up, both intermediate frequency (IF) and radio frequency (RF) signals are transmitted in the spoof SPP modes (Fig. 1a)
Summary
Distinguishing two or more signals with subwavelength separation has accelerated research in many fields, including photonics, super-resolution imaging, and dense communication, which are always hampered by the socalled diffraction limit. Many methods, including far-field time-reversal mirrors[1,2,3] and optical diffraction tomography setups[4,5], have been proposed to break the diffraction limit, these schemes work at the price of slow transmission speed, which makes them inefficient for real-time applications. In contrast to the speed and size limitations of the abovementioned methods, real application scenarios always require robust, flexible, and dynamic far-field transmissions of subdiffraction-limit information, for instance, in the highly dense multiple input multiple output system[13,14,15].
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