Zhou Nan, Wang Jian
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
Sci Rep. 2018 May 23;8(1):8038. doi: 10.1038/s41598-018-26361-0.
Bessel-Gaussian beams have distinct properties of suppressed diffraction divergence and self-reconstruction. In this paper, we propose and simulate metasurface-assisted orbital angular momentum (OAM) carrying Bessel-Gaussian laser. The laser can be regarded as a Fabry-Perot cavity formed by one partially transparent output plane mirror and the other metasurface-based reflector mirror. The gain medium of Nd:YVO enables the lasing wavelength at 1064 nm with a 808 nm laser serving as the pump. The sub-wavelength structure of metasurface facilitates flexible spatial light manipulation. The compact metasurface-based reflector provides combined phase functions of an axicon and a spherical mirror. By appropriately selecting the size of output mirror and inserting mode-selection element in the laser cavity, different orders of OAM-carrying Bessel-Gaussian lasing modes are achievable. The lasing Bessel-Gaussian, Bessel-Gaussian, Bessel-Gaussian and Bessel-Gaussian modes have high fidelities of ~0.889, ~0.889, ~0.881 and ~0.879, respectively. The metasurface fabrication tolerance and the dependence of threshold power and output lasing power on the length of gain medium, beam radius of pump and transmittance of output mirror are also discussed. The obtained results show successful implementation of metasurface-assisted OAM-carrying Bessel-Gaussian laser with favorable performance. The metasurface-assisted OAM-carrying Bessel-Gaussian laser may find wide OAM-enabled communication and non-communication applications.
贝塞尔 - 高斯光束具有抑制衍射发散和自我重构的独特特性。在本文中，我们提出并模拟了基于超表面的携带轨道角动量（OAM）的贝塞尔 - 高斯激光器。该激光器可被视为由一个部分透明的输出平面镜和另一个基于超表面的反射镜形成的法布里 - 珀罗腔。Nd:YVO增益介质在808 nm激光泵浦下实现1064 nm的激光波长。超表面的亚波长结构有助于灵活的空间光操纵。基于超表面的紧凑型反射镜提供了轴棱锥和球面镜的组合相位功能。通过适当选择输出镜的尺寸并在激光腔内插入模式选择元件，可以实现不同阶次的携带OAM的贝塞尔 - 高斯激光模式。激射的贝塞尔 - 高斯、贝塞尔 - 高斯、贝塞尔 - 高斯和贝塞尔 - 高斯模式的保真度分别高达0.889、0.889、0.881和0.879。还讨论了超表面制造公差以及阈值功率和输出激射功率对增益介质长度、泵浦光束半径和输出镜透射率的依赖性。所得结果表明成功实现了具有良好性能的基于超表面的携带OAM的贝塞尔 - 高斯激光器。基于超表面的携带OAM的贝塞尔 - 高斯激光器可能会在广泛的基于OAM的通信和非通信应用中找到用武之地。
