• Chinese Optics Letters
  • Vol. 20, Issue 7, 072601 (2022)
Xiaoying He*, Mengyuan Li, and Lan Rao**
Author Affiliations
  • School of Electronic Engineering, Beijing Key Laboratory of Space-Ground Interconnection and Convergence, and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
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    DOI: 10.3788/COL202220.072601 Cite this Article
    Xiaoying He, Mengyuan Li, Lan Rao. Underwater Bessel-like beams with enlarged depth of focus based on fiber microaxicon[J]. Chinese Optics Letters, 2022, 20(7): 072601 Copy Citation Text show less

    Abstract

    Underwater optical wireless communication, which is useful for oceanography, environmental monitoring, and underwater surveillance, suffers the limit of the absorption attenuation and Mie–Rayleigh scattering of the lights. Here, Bessel-like beams generated by a fiber microaxicon is utilized for underwater wireless propagation. Underwater, the cone angle for generating Bessel-like beams starts from 46°, which is smaller than that in air for Bessel-like beams. When the cone angle of the fiber microaxicons is about 140°, the depth of focus underwater, which is four times as long as the depth of focus in air, has enlarged about 28 µm, 36.12 µm, and 50.7 µm for 470 nm, 520 nm, and 632 nm visible lights. The transmission distance of the Bessel beams for visible lights has been simulated by using Henyey–Greenstein–Rayleigh phase function methods and spectral absorption by bio-optical model due to Monte Carlo methods. The results show that the propagation distance could reach 4000 m, which overcome the limit of the Mie–Rayleigh scattering and absorption attenuation underwater.

    1. Introduction

    Recently, Bessel-like beams generated by the optical fibers-based method are desirable, which is because they could offer a compact, robust, and alignment-free operation compared with bulky optical systems. So far, there are many fiber-based methods for generating Bessel-like beams, such as fiber microaxicons[13], self-growing micro-tips[4], or a tapered hollow tube[5]. Another way is utilizing a long-period grating to excite higher-order cladding mode and then generate Bessel beams with controllable diffraction-resistant distance[6]. These non-diffracting Bessel-like beams have attracted increasing interest owing to their unique light intensity distributions and self-healing propagation properties, which have been widely used in various domains such as optical trapping[7] and manipulation[8], high-order harmonic generation[9], nonlinear optics[10], and material processing[11]. Especially, such properties can also be used in optical wireless communication to overcome the diffraction limits and particle scattering[12], even if encountering opaque obstacles.

    Copy Citation Text
    Xiaoying He, Mengyuan Li, Lan Rao. Underwater Bessel-like beams with enlarged depth of focus based on fiber microaxicon[J]. Chinese Optics Letters, 2022, 20(7): 072601
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