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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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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 Copy Citation Text show less

Abstract

Optical superoscillation refers to an intriguing phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit, hence improving the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Here, we report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, but also completely eliminates side lobes in a particular dimension. We demonstrate a new mechanism for achieving such a wave form based on a pair of moonlike sharp-edge apertures. The resultant superoscillatory wave exhibits Bessel-like forms, hence allowing long-distance propagation of subwavelength structures. The result facilitates the study of optical superoscillation and on a fundamental level eliminates the compromise between the superoscillatory feature size and the field of view.

1 Introduction

Owing to the wave nature of optical diffraction, it is extremely challenging to achieve a highly localized wave packet in free space, which essentially limits the imaging performance of an optical system. In 1873, Erns Abbe first introduced the concept of optical diffraction limit,1 which is a constraint on the smallest light spot with a spatial size of about $λ/2$, where $λ$ is the optical wavelength. Essentially, the diffractive light wave with high spatial frequency, named an evanescent wave, tends to exist on the near-field surface of an object and decays exponentially with distance. As a result, delicate information of the object carried by the evanescent wave cannot be delivered to the far-field region. In the past, substantial effort was made to break such a diffraction barrier24 so as to achieve higher spatial resolution.2,5,6 The earlier developed techniques were mainly focused on exploiting high-spatial-frequency evanescent waves with a nanotip,7,8 superlens,911 or hyperlens.12 But, these methods encounter serious limitations of near-field manipulations or unattainable fabrications. Later on, different fluorescent labeling technologies were proposed to overcome the diffraction barrier in the far field.5,13,14 Despite their ultrahigh resolving property, these techniques depend on fluorescent labeling and require careful calibration with specific dye molecules.

Copy Citation Text
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