We experimentally demonstrate that ptychographic coherent diffractive imaging can be used to simultaneously characterize the amplitude and phase of bichromatic orbital angular momenta-shaped vortex beams, which consist of a fundamental field, together with its copropagating second-harmonic field. In contrast to most other orbital angular momentum characterization methods, this approach solves for the complex field of a hyperspectral beam. This technique can also be used to characterize other phase-structured illumination beams, and, in the future, will be able to be extended to other complex fields in the extreme ultraviolet or X-ray spectral regions, as well as to matter waves.
Esashi, Y; Liao, C-T; Wang, B; Brooks, N; Dorney, K M; Hernández-García, C; Kapteyn, H; Adams, D; and Murnane, M, "Ptychographic amplitude and phase reconstruction of bichromatic vortex beams." (2018). Physics Faculty Contributions. 129.