Kotlyar Victor V, Kovalev Alexey A, Porfirev Alexey P
Opt Express. 2019 Apr 15;27(8):11236-11251. doi: 10.1364/OE.27.011236.
Two simple and high-efficiency techniques for measuring the orbital angular momentum (OAM) of paraxial laser beams are proposed and studied numerically and experimentally. One technique relies on measuring the intensity in the Fresnel zone, followed by calculating the intensity that is numerically averaged over angle at discrete radii and deriving squared modules of the light field expansion coefficients via solving a linear set of equations. With the other technique, two intensity distributions are measured in the Fourier plane of a pair of cylindrical lenses positioned perpendicularly, before calculating the first-order moments of the measured intensities. The experimental error grows almost linearly from ~1% for small fractional OAM (up to 4) to ~10% for large fractional OAM (up to 34).
提出了两种用于测量傍轴激光束轨道角动量（OAM）的简单高效技术，并进行了数值和实验研究。一种技术依赖于测量菲涅尔区的强度，然后计算在离散半径处角度上进行数值平均后的强度，并通过求解一组线性方程得出光场展开系数的平方模。对于另一种技术，在计算测量强度的一阶矩之前，先在一对垂直放置的柱面透镜的傅里叶平面中测量两个强度分布。实验误差几乎呈线性增长，从小分数OAM（高达4）时的约1%增长到大分数OAM（高达34）时的约10%。
