Tuniz Alessandro, Kuhlmey Boris T
Institute of Photonics and Optical Science, School of Physics, University of Sydney, Camperdown, NSW, 2006, Australia.
The University of Sydney Nano Institute, The University of Sydney, Camperdown, NSW, 2006, Australia.
Nat Commun. 2023 Oct 18;14(1):6393. doi: 10.1038/s41467-023-41949-5.
Imaging with resolutions much below the wavelength λ - now common in the visible spectrum - remains challenging at lower frequencies, where exponentially decaying evanescent waves are generally measured using a tip or antenna close to an object. Such approaches are often problematic because probes can perturb the near-field itself. Here we show that information encoded in evanescent waves can be probed further than previously thought, by reconstructing truthful images of the near-field through selective amplification of evanescent waves, akin to a virtual superlens that images the near field without perturbing it. We quantify trade-offs between noise and measurement distance, experimentally demonstrating reconstruction of complex images with subwavelength features down to a resolution of λ/7 and amplitude signal-to-noise ratios < 25dB between 0.18-1.5 THz. Our procedure can be implemented with any near-field probe, greatly relaxes experimental requirements for subwavelength imaging at sub-optical frequencies and opens the door to non-invasive near-field scanning.
分辨率远低于波长λ（在可见光谱中现在很常见）的成像在较低频率下仍然具有挑战性，在较低频率下，指数衰减的倏逝波通常使用靠近物体的尖端或天线来测量。这种方法往往存在问题，因为探头会干扰近场本身。在这里，我们表明，通过对倏逝波进行选择性放大来重建近场的真实图像，可以比以前认为的更远地探测编码在倏逝波中的信息，这类似于一个虚拟超透镜，它可以对近场进行成像而不干扰它。我们量化了噪声与测量距离之间的权衡，通过实验证明了具有亚波长特征的复杂图像的重建，分辨率低至λ/7，在0.18 - 1.5太赫兹之间的幅度信噪比<25分贝。我们的方法可以用任何近场探头来实现，极大地放宽了亚光频率下亚波长成像的实验要求，并为非侵入性近场扫描打开了大门。
