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Author

Shuo Zhang

Bio: Shuo Zhang is an academic researcher from Chongqing University. The author has contributed to research in topics: Lens (optics) & Diffraction. The author has an hindex of 4, co-authored 4 publications receiving 49 citations.

Papers
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Journal ArticleDOI
TL;DR: A method based on the idea of compressing a normalized angular spectrum is developed, which makes it possible and provides a practical tool for the design of a quasi-non-diffracting beam with super-oscillatory sub-wavelength transverse size.
Abstract: Quasi-non-diffracting beams are attractive for various applications, including optical manipulation, super-resolution microscopes, and materials processing. However, it is a great challenge to design and generate super-long quasi-non-diffracting beams with sub-diffraction and sub-wavelength size. In this paper, a method based on the idea of compressing a normalized angular spectrum is developed, which makes it possible and provides a practical tool for the design of a quasi-non-diffracting beam with super-oscillatory sub-wavelength transverse size. It also presents a clear physical picture of the formation of super-oscillatory quasi-non-diffracting beams. Based on concepts of a local grating and super-oscillation, a lens was designed and fabricated for a working wavelength of λ = 632.8 nm. The validity of the idea of normalized angular spectrum compression was confirmed by both numerical investigations and experimental studies. An optical hollow needle with a length of more than 100λ was experimentally demonstrated, in which an optical hollow needle was observed with a sub-diffraction and sub-wavelength transverse size within a non-diffracting propagation distance of 94λ. Longer non-diffracting propagation distance is expected for a lens with larger radius and shorter effective wavelength.

25 citations

Journal ArticleDOI
TL;DR: An optimization-free design approach is proposed and the possibility of generating sub-diffraction quasi-non-diffracting beams with sub-wavelength size for different polarizations by a binary-phase Fresnel planar lens is demonstrated.
Abstract: Sub-diffraction quasi-non-diffracting beams with sub-wavelength transverse size are attractive for applications such as optical nano-manipulation, optical nano-fabrication, optical high-density storage, and optical super-resolution microscopy. In this paper, we proposed an optimization-free design approach and demonstrated the possibility of generating sub-diffraction quasi-non-diffracting beams with sub-wavelength size for different polarizations by a binary-phase Fresnel planar lens. More importantly, the optimization-free method significantly simplifies the design procedure and the generation of sub-diffracting quasi-non-diffracting beams. Utilizing the concept of normalized angular spectrum compression, for wavelength λ0 = 632.8 nm, a binary-phase Fresnel planar lens was designed and fabricated. The experimental results show that the sub-diffraction transverse size and the non-diffracting propagation distances are 0.40λ0–0.54λ0 and 90λ0, 0.43λ0–0.54λ0 and 73λ0, and 0.34λ0–0.41λ0 and 80λ0 for the generated quasi-non-diffracting beams with circular, longitudinal, and azimuthal polarizations, respectively.

24 citations

Journal ArticleDOI
TL;DR: A binary-phase planar lens with an ultra-long focal length (300λ) for the generation of a 3D hollow spot with a cylindrical vector wave provides a promising way to achieve tight 3D optical confinement for different uses that might find applications in super-resolution microscopy, nano-lithography, high-density data storage, Nano-particle optical manipulation, and nano-optical manufacturing.
Abstract: A three-dimensional (3D) hollow spot is of great interest for a wide variety of applications such as microscopy, lithography, data storage, optical manipulation, and optical manufacturing. Based on conventional high-numerical-aperture objective lenses, various methods have been proposed for the generation of 3D hollow spots for different polarizations. However, conventional optics are bulky, costly, and difficult to integrate. More importantly, they are diffraction-limited in nature. Owing to their unique properties of small size, light weight, and ease of integration, planar lenses have become attractive as components in the development of novel optical devices. Utilizing the concept of super-oscillation, planar lenses have already shown great potential in the generation of sub-diffraction, or even of super-oscillatory features, in propagating optical waves. In this paper, we propose a binary-phase planar lens with an ultra-long focal length (300λ) for the generation of a 3D hollow spot with a cylindrical vector wave. In addition, we experimentally demonstrate the formation of such a hollow spot with a sub-diffraction transverse size of 0.546λ (smaller than the diffraction limit of 0.5λ/NA, where NA denotes the lens numerical aperture) and a longitudinal size of 1.585λ. The ratio of central minimum intensity to the central ring peak intensity is less than 3.7%. Such a planar lens provides a promising way to achieve tight 3D optical confinement for different uses that might find applications in super-resolution microscopy, nano-lithography, high-density data storage, nano-particle optical manipulation, and nano-optical manufacturing.

23 citations

Journal ArticleDOI
TL;DR: A family of reflective cross-shaped quarter-wave birefringent metasurfaces is proposed to achieve full control of polarization and phase of reflected waves and two meta-mirrors are designed with integrated functions of polarization conversion and sub-diffraction focusing.
Abstract: Independent manipulation of phase and polarization of optical fields is of great interest in various applications, including vector-field generation, optical tweezers, and nanolithography. The integration of phase and polarization manipulation on a single optical device may greatly simplify optical systems and eases optical alignment. In this Letter, a family of reflective cross-shaped quarter-wave birefringent metasurfaces is proposed to achieve full control of polarization and phase of reflected waves. Based on the proposed metasurfaces, two meta-mirrors are designed with integrated functions of polarization conversion and sub-diffraction focusing. Numerical investigations also reveal the achromatic focusing performance of the two meta-mirrors. The proposed metasurfaces with independent manipulation of polarization and phase provide flexible building blocks for constructing complicated vector optical fields.

13 citations

Journal ArticleDOI
TL;DR: In this paper , a planar waveguide and chirped Bragg grating are simultaneously generated using a KrF excimer laser and a phase mask covered by a quartz chrome mask.
Abstract: A novel tactile sensor for two-dimensional force location measurements, based on polymer-based planar waveguide chirped Bragg gratings (PPCBGs) fabricated on sheet PMMA substrate, is presented. The planar waveguide and chirped Bragg grating are simultaneously generated using a KrF excimer laser and a phase mask covered by a quartz chrome mask. Location and magnitude of an applied force is measured by observing the change of the wavelength of a dip in the measured spectrum and a change in the reflectivity intensity. Experimental characterization indicates submillimeter spatial resolution of applied force in the range of 1-4 N with a sensitivity of 947.02 pm/mm.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: Super-oscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals as discussed by the authors, which has implications for information theory and applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience.
Abstract: Superoscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals. Modern studies originated in quantum theory, but there were anticipations in radar and optics. The mathematical understanding—still being explored—recognises that functions are extremely small where they superoscillate; this has implications for information theory. Applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience are now moving from the theoretical and the demonstrative to the practical. This Roadmap surveys all these areas, providing background, current research, and anticipating future developments.

127 citations

Journal ArticleDOI
TL;DR: Recent developments in optical ‘superoscillation’ technologies are reviewed, which aim to overcome current limitations in superresolution techniques requiring contact with the observed object, the use of fluorescent labels, or viewing that is restricted to the near-field of a lens.
Abstract: The resolution of conventional optical elements and systems has long been perceived to satisfy the classic Rayleigh criterion. Paramount efforts have been made to develop different types of superresolution techniques to achieve optical resolution down to several nanometres, such as by using evanescent waves, fluorescence labelling, and postprocessing. Superresolution imaging techniques, which are noncontact, far field and label free, are highly desirable but challenging to implement. The concept of superoscillation offers an alternative route to optical superresolution and enables the engineering of focal spots and point-spread functions of arbitrarily small size without theoretical limitations. This paper reviews recent developments in optical superoscillation technologies, design approaches, methods of characterizing superoscillatory optical fields, and applications in noncontact, far-field and label-free superresolution microscopy. This work may promote the wider adoption and application of optical superresolution across different wave types and application domains.

84 citations

Journal ArticleDOI
31 Mar 2020
TL;DR: In this article, Abbe-Rayleig et al. showed that traditional optical lenses and the corresponding imaging systems, which are based on the optical paths when light propagates inside the bulky media, usually suffer from the bulky size.
Abstract: Traditional optical lenses and the corresponding imaging systems, which are based on the optical paths when light propagates inside the bulky media, usually suffer from the bulky size, Abbe-Rayleig...

25 citations