Abstract
Non-diffracting Bessel beams, including zero-order and high-order Bessel Beams which carry orbital angular momentum (OAM), enable a variety of important applications in optical micromanipulation, sub-diffraction imaging, high speed photonics/quantum communication, etc. The commonly used ways to create Bessel beams, including an axicon or a digital hologram written to a spatial light modulator (SLM), have great challenges to operate at the nanoscale. Here we theoretically design and experimentally demonstrate one kind of planar Bessel beam generators based on metasurfaces with analytical structures perforated in ultra-thin metallic screens. Continuous phase modulation between 0 to 2π is realized with a single element. In addition, due to the dispersionless phase shift stemming from spin-orbit interaction, the proposed device can work in a wide wavelength range. The results may find applications in future optical communication, nanofabrication and super-resolution imaging, etc.
Highlights
Non-diffracting Bessel beams, including zero-order and high-order Bessel Beams which carry orbital angular momentum (OAM), enable a variety of important applications in optical micromanipulation, sub-diffraction imaging, high speed photonics/quantum communication, etc
High-order Bessel beams (HOBBs), i.e., Bessel beams carrying orbital angular momentum (OAM) have attracted growing interest owing to their ability to transport information encoded in the OAM basis[11,12]
The diffraction-free property of the Bessel beam, combined with the infinite freedoms of OAM, makes the high-order Bessel beams (HOBBs) become a promising alternative for high-speed optical and quantum communications systems
Summary
Principle and design of Bessel beam generators. A general design procedure for Bessel beams generators can be obtained from the principle of holography. Bessel beam generators for topological charges l = 0, 2, 3 and 4, were fabricated in our experiment. A collimated beam from a He-Ne laser at λ = 632.8 nm was converted into right-hand polarization (RCP) light through cascaded polarizer and quarter-wave plate, and illuminated on the samples. The intensity distribution of the fields was imaged a polarizer laser sample b l=2 lens 1 c l=3 lens 2 LCP/RCP d. We measured the intensity distribution of the fields in a serial image planes by moving the objective along the z direction (propagation direction of the Bessel beam) with a step of 1 μm, mapped the longitudinal cross-sections of the generated Bessel beams. We measured the propagation property of 20 a b c
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