Tailoring Large Asymmetric Laguerre–Gaussian Beam Array Using Computer-Generated Holography

Abstract

Laguerre–Gaussian beams are structured light beams with a donut-shaped symmetric intensity profile and a helical phase profile. The beam profile is defined by a quantized parameter known as the mode number which extends to infinity. The availability of unbounded modes makes these beams a promising candidate for next-generation optical computing, and optical communication technologies. The symmetric intensity profile of a Laguerre–Gaussian beam can be made asymmetric through certain techniques and these beams are known by the term `asymmetric Laguerre–Gaussian beams’. Here, the asymmetricity adds another degree of freedom to the beam (apart from its mode number) which helps in encoding more information compared to a symmetric beam. However, in order to harness the benefits of all the available degrees of freedom, it is required to generate a large number of such beams in a multiplexed fashion. Here, we report the generation of such a large array of asymmetric Laguerre–Gaussian beams for the first time. Computer-generated holography and spatial multiplexing techniques were employed to generate a large array comprising of 12 × 16 = 192 asymmetric Laguerre–Gaussian beams with an arbitrary mode index and asymmetricity.

Generalized Asymmetric Hermite–Gaussian and Laguerre–Gaussian Beams

“…The proposed generalized asymmetrical laser beams can be realized using an SLM, with the adoption of some techniques for the encoding and amplitude-phase function into a phase-only one [52,53], utilized for data transmission through atmospheric turbulence. The scale parameters and the parameter controlling the asymmetry degree offer additional degrees of freedom [54] enabling the creation of a beam least prone to distortion due to turbulence. We note that attractive beams for optical communications are non-diffractive beams such as Bessel beams [55] or Airy beams [56].…”

Planar crossed-fork gratings with sinusoidal transmittance for eliminating high-order diffraction

“…Optical vortex arrays (OVAs), due to their ability to process data in parallel using spatial degrees of freedom, has recently seen notable applications in optical communication, 1 – 4 high-resolution far-field microscopy, 5 orbital angular momentum (OAM) multiplexing, 6 , 7 optical anti-counterfeiting, 8 , 9 and strong data encoding 10 – 14 Thus, considerable effort has been devoted to developing methods for realizing OVAs 15 – 23 Currently, three commonly used methods for generating OVAs are multi-beam interference, 24 – 26 specifically microstructured materials, 27 and customized diffraction gratings.…”