Fig. 2: The quasi-radial memory effect in MMFs.

Each row shows simulations of a sequence of distal intensity patterns obtained by applying an input modulation O = PMP⁻¹ using M = diag[e^ipδρ], for increasing δρ, where the initial distal field (left most panel) is a diffraction limited spot at four different radial coordinates: on the fibre axis (a), just off fibre axis (b), midway between fibre axis and core-cladding boundary (c), and near core-cladding boundary (d). The scale-bar indicates the relative intensity within each panel. We see a variety of different predominantly radial transformations take place. We emphasise that all of these transformations are independent of the length of the fibre (i.e., independent of the complex values of the elements of D). We also note that if the initial spot position is rotated about the fibre axis, so are these output fields, by virtue of the rotational memory effect³⁵.