We report the first experimental generation of high-order Mathieu beams and confirm their propagation invariance over a limited range. In our experiment we use a computer-generated phase hologram. The peculiar behaviour of the vortices in Mathieu beams gives rise to questions about their orbital-angular-momentum content, which we calculate by performing a decomposition in terms of Bessel beams.

Holographic generation and orbital angular momentum of high-order Mathieu beams : Special issue on atoms and angular momentum of light

Metalens, a prominent application of two-dimensional metasurfaces, has demonstrated powerful abilities even beyond traditional optical lenses. By manipulating the phase distribution of metalens composed of appropriately arranged nanoscale building blocks, the wavefront of incident wave can be controlled based on Huygens principle, thus achieving the desired reflected and transmitted wave for many different purposes. Metalenses will lead a revolution in optical imaging due to its flat nature and compact size, multispectral acquisition and even off-axis focusing. Here, we review the recent progress of metalenses presenting excellent properties, with a focus on the imaging application using these metalenses. We firstly discuss the mechanism for achieving metalenses with high efficiency, large numerical aperture, controlling the chromatic dispersion or monochromatic aberrations and large area fabrication. Then, we review several important imaging applications including wide-band focusing imaging, polarization dependent imaging, light field imaging and some other significant imaging systems in different areas. Finally, we make a conclusion with an outlook on the future development and challenges of this developing research field.

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Imaging based on metalenses

We demonstrate a novel approach to femtosecond microfabrication of transparent dielectrics, which employs nondiffracting Bessel beams instead of the conventionally used Gaussian beams. The main advantage of Bessel beams is the possibility of recording linear photomodified tracks, extending along the lines of nondiffractive beam propagation without sample translation, as would be required for Gaussian beams. Recording of patterns with an aspect ratio of up to 102–103 in vitreous silica using amplified femtosecond Ti:saphire laser pulses is demonstrated.

Application of Bessel Beams for Microfabrication of Dielectrics by Femtosecond Laser : Instrumentation, Measurement, and Fabrication Technology

P Hariharan 1984 Cambridge: Cambridge University Press xii + 319 pp price £35 ISBN 0 521 24348 3 It is the declared aim of the author of this book to provide a 'self-contained treatment of the principles, techniques and applications of optical holography with particular emphasis on recent developments'. He has covered a wide range of topics in this expanding field at a level which is suitable for both the student and research worker.

https://iopscience.iop.org/article/10.1088/0031-9112/36/4/047/pdf

Optical Holography: Principles, Techniques and Applications

A quantitative analysis of optical fields is essential, particularly when the light is structured in some desired manner, or when there is perhaps an undesired structure that must be corrected for. A ubiquitous procedure in the optical community is that of optical mode projections—a modal analysis of light—for the unveiling of amplitude and phase information of a light field. When correctly performed, all the salient features of the field can be deduced with high fidelity, including its orbital angular momentum, vectorial properties, wavefront, and Poynting vector. Here, we present a practical tutorial on how to perform an efficient and effective optical modal decomposition, with emphasis on holographic approaches using spatial light modulators, highlighting the care required at each step of the process.

Modal analysis of structured light with spatial light modulators: a practical tutorial.

Dielectric meta-surface optical elements are of interest for a variety of interests, one of which is due to their high efficiency. Elements with binary structures that are easy to fabricate can have more than two phase levels, unlike diffractive elements. Previously reported work on meta-surfaces for complex light generation has focused mainly on beams with orbital angular momentum or Bessel beams. A few papers also talk about Airy beams. The latter have been found to have important applications in areas such as light sheet microscopy. These earlier papers describe the meta-surfaces in detail without dwelling on the various design and fabrication steps required to achieve a highly efficient element. Therefore, in this paper, we describe the design process in detail and highlight the key parameters that must be carefully optimized for successful fabrication. Finally, test results of a highly efficient, dielectric meta-surface cubic phase plate (CPP) are presented. The element has 8 phase levels and generates an Airy beam at the wavelength of 1064 nm. The focus of this work is to present a detailed step-by-step design flow, as well as the means by which to optimize the fabrication of those 8 levels. The phase variation is achieved by a change in the lateral dimensions. While the sizes are unique for each phase level, they are all sub-micron and this is where the fabrication challenge lies.

Raghu Dharmavarapu

Papers

Design and optimized fabrication techniques for highly-efficient dielectric meta-optical Airy beam generators