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• Vol. 3, Issue 4, 045002 (2021)
Yanwen Hu1, Shiwang Wang1, Junhui Jia1, Shenhe Fu1、2、*, Hao Yin1、2, Zhen Li1、2、*, and Zhenqiang Chen1、2
Author Affiliations
• 1Jinan University, Department of Optoelectronic Engineering, Guangzhou, China
• 2Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Guangzhou, China
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Fig. 1. Principle for generating the no-side-lobe optical superoscillatory waves with a pair of symmetric moonlike apertures. (a) Design processes for the moonlike apertures. (b) The moonlike apertures were fabricated with an extremely thin gold film deposited on a glass substrate. (c) An electron micrograph of one of the fabricated samples. (d) Experimental setup used to validate the binary amplitude modulation of the moonlike apertures as well as to measure the diffractive waves in the far field with an He–Ne laser working at a wavelength of $λ=633 nm$. (e), (f) Initial measurement of the output field from the sample: (e) intensity distribution in the $x–y$ plane; (f) cross-section of the light field as marked with a white line in (e). The blue curve denotes the experiment, while the red curve shows the theory.
Fig. 2. Experimental and numerical demonstrations of the generated superoscillatory light waves with the moonlike nanostructure (parameters: $d=15 μm$ and $ω=2 μm$). (a)–(c) The intensity distributions of the diffractive light waves in the transverse plane at different distances: (a) $z=4.9 μm$, (b) $z=5.5 μm$, and (c) $z=6.2 μm$. The panels in the second and the fourth columns are the zoom-in intensity distributions. Panels in each column share the same scale. The wavelength used here is $λ=633 nm$.
Fig. 3. The intensity cross-sections of the superoscillatory lobes at different distances: (a), (b) $z=4.9 μm$; (c), (d) $z=5.5 μm$; and (e), (f) $z=6.2 μm$. (a), (c), (e) The intensity profiles along the $x$ axis ($y=0$); (b), (d), (f) the intensity profiles along the $y$ axis ($x=0$). The corresponding FWHMs were indicated experimentally in the panels. The blue curves represent the experiments, while the red curves denote the simulations based on Eq. (2). The wavelength used here is $λ=633 nm$.
Fig. 4. Generation of the superoscillatory light waves with a smaller moonlike nanostructure ($d=8 μm$ and $ω=2 μm$). (a), (b) The simulated intensity distributions of the diffractive fields at distances of (a) $z=2.9 μm$ and (b) $z=4.0 μm$. (c), (d) The corresponding experimental measurements of (a) and (b), respectively. (e), (f) Intensity profiles along the $y$ coordinate. The FWHM values of the profiles were measured as 221 and 276 nm. Blue and red curves show the experiment and the simulation [based on Eq. (2)], respectively. Panels (a)–(d) share the same scale. The labeled FWHMs in (e) and (f) refer to the experimental data.
Fig. 5. Free-space propagation of the generated superoscillatory waves. The panels depict the measured intensity distributions of the light waves in the $y–z$ plane in the cases of (a), (b) $d=8 μm$ and (c), (d) $d=15 μm$. (a), (c) The simulated results based on Eq. (2), whereas panels (b) and (d) present the corresponding experiments.
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Yanwen Hu, Shiwang Wang, Junhui Jia, Shenhe Fu, Hao Yin, Zhen Li, Zhenqiang Chen. Optical superoscillatory waves without side lobes along a symmetric cut[J]. Advanced Photonics, 2021, 3(4): 045002