Abstract
Singular beams which possess helical phase wavefront or spatially inhomogeneous polarization provide new freedom for optical field manipulation. However, conventional schemes to produce the singular beams have difficulty in realizing the flexible switch between different singular beams. In this work, we have experimentally demonstrated the capability of dielectric metasurfaces to generate three types of singular beams and switch between them at working wavelength of 1550 nm. We have shown vortex beam and cylindrical vector beam generation with single metasurface and cylindrical vector vortex beam generation with two cascaded metasurfaces. Moreover, experimental demonstration on switching cylindrical vector beam into vortex beam has also been done by combining one quarter-wave plate and a Glan laser polarizer. The experimental results match well with the analysis from the Jones matrix calculations. The average conversion efficiency of cylindrical vector beam to vortex beam was estimated to be 47.7%, which was about 2.3% lower than the theoretical prediction.
Highlights
Singular beam, which usually has a doughnut-like intensity profile in the transverse plane, has been widely studied for various applications due to its unique optical properties[1, 2]
We have experimentally demonstrated the generation of cylindrical vector beam (CVB), vortex beam (VB) and cylindrical vector vortex (CVV) beams and the flexible switching between them based on dielectric metasurfaces which are fabricated by writing space-variant grooves in a silica glass
In order to further demonstrate the flexibility in switching between these singular beams, a system comprising of a quarter-wave plate and a Glan laser polarizer was well-designed for transforming CVB into linearly polarized VB
Summary
Singular beam, which usually has a doughnut-like intensity profile in the transverse plane, has been widely studied for various applications due to its unique optical properties[1, 2]. Polarization singularity, which has spatially inhomogeneous polarization distribution across its cross-section, is usually referred to cylindrical vector beam (CVB)[2] Both VB and CVB has attracted much attention due to their unique optical properties and have shown exciting perspective in various applications ranging from optical manipulation to imaging and optical communication etc[3,4,5,6,7,8,9,10,11,12,13]. It is found that only spatial light modulator (SLM) and radial polarization converter[18, 20, 24,25,26,27,28] could be used to produce all of them (CVB, VB and CVV beam). The average conversion efficiency of VB to CVV beam can be as high as 82.4%
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