Design, fabrication and characterization of subwavelength computer-generated holograms for spot array generation

Abstract

We report the analysis, design, fabrication and experimental characterization of novel subwavelength computer-generated holograms that produce uniform symmetric spot array. We distinguish between a polarization-sensitive and polarization-insensitive far-field reconstruction and show that a linearly polarized incident illumination is required in the former case in order to generate a symmetric reconstruction. The polarization-insensitive case generates a symmetric response independent of the illumination polarization. We show that this response is equivalent to that of a scalar-based computer-generated hologram but with an additional, independent, term that describes the undiffracted zeroth order. These findings simplify the design and optimization of form birefringent computer-generated holograms (F-BCGH) significantly. We present experimental results that verify our analysis and highlight the advantage of these novel elements over scalar-designed elements.

Optically resonant dielectric nanostructures

“…Another approach to achieving phase control was proposed in the early 2000s, and it relies on metallic or dielectric subwavelength gratings with different orientations to control the circularly polarized light through a geometric PancharatnamBerry (PB) phase (77,78). A recent work based on this principle demonstrated flat silicon lenses and axicons operating at visible wavelengths (Fig.…”

High‐transmission dielectric metasurface with 2π phase control at visible wavelengths

“…Due to their two-dimensional nature, it is therefore possible to Data Storage Institute, A*STAR (Agency for Science, Technology and Research), 5 Engineering Drive 1, 117608, Singapore * * Equal contribution * Corresponding authors: e-mails: yu_yefeng@dsi.a-star.edu.sg, arseniy_k@dsi.a-star.edu.sg realize planar analogs of traditional optical components, such as lenses, beam transformers, broadband pass filters, wave plates and polarization converters [2][3][4]. In addition, new functionalities arising from phase discontinuities at an interface can also be obtained, such as beam deflection [5][6][7], beam forming [8][9][10][11][12], and holography [13][14][15]. Plasmonic-based metasurfaces achieve the required full 2π phase control primarily using two different approaches.…”

Experimental Demonstration of a Highly Efficient Fan-out Polarization Grating

“…Given the three space-variant parameters (the phase bias α(x), the relative phase retardation Γ(x) and the azimuth angle φ(x)) expressed in equation (5)–(7), the fan-out polarization grating can be fabricated and physically realized via metasurfaces1819 or form-birefringence structures20. In the current paper, we perform a demonstration with the use of a vector beam generator23 to produce the transmitted field of the polarization grating, and measure the intensity distribution and polarization states in the back focal plane of a Fourier lens L7 as shown in Fig.…”

“…9(d) to (f). The fan-out uniformity is defined as the ratio between the minimal and the maximal intensity within the array20. The theoretical uniformity of a duplicator, a triplicator and a 1-by-4 splitter are unity as demonstrated in Fig.…”

“…The purpose of this paper is to present an experimental demonstration of the validity of the fan-out polarization grating design. The actual gratings should be fabricated with metasurfaces1819 or form-birefringence structures20 which would be compact, robust and highly efficient. The high efficiency and the ability of controlling the individual polarization states of split beams make this fan-out polarization grating useful to laser beam combining systems.…”