分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Retroreflectors that can accurately redirect the incident wave in free space back along its original channel provide unprecedented opportunities for light manipulation in wireless communication. However, to the best of our knowledge, the existing methods of designing retroreflectors suffer from either the bulky size, narrow angular bandwidth, or time-consuming post-processing. Here, a scheme of designing ultrathin and all-angle retroreflectors based on hyperbolic plasmonic metasurfaces is proposed and experimentally demonstrated. The physical mechanism underlying this scheme is the high-efficiency all-angle transition between the traveling waves in free space and the canalized spoof surface plasmon (SSP) on the hyperbolic plasmonic metasurfaces (HPMs). In this case, the strong confinement characteristic benefited from the enhanced light-matter interaction enables us to route and retroreflect the canalized SSP with extremely ultrathin structures. As proof of the scheme, a retroreflector prototype with a thickness approximately equal to the central wavelength is designed and fabricated. Further experimental investigation obtains a maximum efficiency of 83.2% and a half-power field of view up to 53{\deg}. This scheme can find promising applications in target detection, remote sensing, and diverse on-chip light control devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Inspired by the capability of structured illumination microscopy in subwavelength imaging, many researchers devoted themselves to investigating this methodology. However, due to the free propagating feature of the traditional structured illumination fields, the resolution can be only improved up to double times compared with the diffractied limited microscopy. Besides, most of the previous studies, relying on incoherent illumination sources, are restricted to fluorescent samples. In this work, a subwavelength nonfluorescent imaging method is proposed based on the terahertz traveling wave and plasmonics illumination. Excited along with a metal grating, the spoof surface plasmons are employed as the plasmonics illumination. When the scattering waves with the SSPs illumination are captured, the high order spatial frequency components of the sample are already encoded into the obtainable low order ones. Then, an algorithm is summarized to shift the modulated SF components to their actual positions in the Fourier domain. In this manner, high order SF components carrying the fine information are introduced to reconstruct the desired imaging, leading to an improvement of the resolution up to 0.12 lambda. Encouragingly, the resolution can be further enhanced by tuning the working frequency of the SSPs. This method holds promise for some important applications in terahertz nonfluorescent microscopy and sample detection with weak scattering.
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