Does the structure of light influence the speckle size?

Authors :: Carmelo Rosales-Guzmán
Meng-Xuan Dong
Xiao-Bo Hu
Zhi-Han Zhu
Wei Gao
Source :: Scientific Reports, Scientific Reports, Vol 10, Iss 1, Pp 1-11 (2020)
Publication Year :: 2020
Publisher :: Springer Science and Business Media LLC, 2020.
Abstract: It is well known that when a laser is reflected from a rough surface or transmitted through a diffusive medium, a speckle pattern will be formed at a given observation plane. Speckle is commonly produced by laser beams with a homogeneous intensity, for which, well-known relations have been derived, relating the speckle size to the area of illumination. Here we investigate the speckle generated by higher-order Laguerre-Gaussian (LG) modes, characterized by a non-uniform intensity distribution of concentric rings.We show that the ring-structure of the LG modes does not play any role in the speckle size, which happens to be the same as that obtained for a homogeneous intensity distribution. This allow us to provide with a simple expression that relates the speckle size to the spot size of the LG modes. Our findings will be of great relevance in many speckle-based applications.<br />Comment: 5 pages, 5 figures