物理
贝塞尔函数
拓扑量子数
梁(结构)
光学
旋涡
瑞利长度
光束
角动量
平方米
光轴
空(SQL)
激光束质量
量子力学
激光器
激光束
数据库
计算机科学
镜头(地质)
作者
V. V. Kotlyar,A. A. Kovalev,Р. В. Скиданов,В. А. Сойфер
标识
DOI:10.1364/josaa.31.001977
摘要
We propose a three-parameter family of asymmetric Bessel–Gauss (aBG) beams with integer and fractional orbital angular momentum (OAM). The aBG beams are described by the product of a Gaussian function by the nth-order Bessel function of the first kind of complex argument, having finite energy. The aBG beam’s asymmetry degree depends on a real parameter c≥0: at c=0, the aBG beam is coincident with a conventional radially symmetric Bessel–Gauss (BG) beam; with increasing c, the aBG beam acquires a semicrescent shape, then becoming elongated along the y axis and shifting along the x axis for c≫1. In the initial plane, the intensity distribution of the aBG beams has a countable number of isolated optical nulls on the x axis, which result in optical vortices with unit topological charge and opposite signs on the different sides of the origin. As the aBG beam propagates, the vortex centers undergo a nonuniform rotation with the entire beam about the optical axis (c≫1), making a π/4 turn at the Rayleigh range and another π/4 turn after traveling the remaining distance. At different values of the c parameter, the optical nulls of the transverse intensity distribution change their position, thus changing the OAM that the beam carries. An isolated optical null on the optical axis generates an optical vortex with topological charge n. A vortex laser beam shaped as a rotating semicrescent has been generated using a spatial light modulator.
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