Influence of atmospheric turbulence on optical communications using orbital angular momentum for encoding

Author(s): Mehul Malik, Malcolm O’Sullivan, Brandon Rodenburg, Mohammad Mirhosseini, Jonathan Leach, Martin P. J. Lavery, Miles J. Padgett, and Robert W. Boyd Abstract: “We describe an experimental implementation of a free-space 11-dimensional communication system using orbital angular momentum (OAM) modes. This system has a maximum measured OAM channel capacity of 2.12 bits/photon. The effects of Kolmogorov thin-phase turbulence on the OAM channel capacity are quantified. We find that increasing the turbulence leads to a degradation of the channel capacity. We are able to mitigate the effects of turbulence by increasing the spacing between detected OAM modes. This study has implications…

Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator

Author(s): Miao Lin, Kouichi Nitta, Osamu Matoba, and Yasuhiro Awatsuji Abstract: “Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.” Link to Publications Page Publication: Applied Optics, (subscription required) Issue/Year/DOI: Applied Optics, Vol. 51, Issue 14, pp. 2633-2637 (2012) doi:10.1364/AO.51.002633

An active coronagraph using a liquid crystal array for exoplanet imaging: principle and testing

Author(s): Xi Zhang, De-Qing Ren, Yong-Tian Zhu and Jiang-Pei Dou. Abstract: “High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array (LCA) for active pupil apodization and a deformable mirror (DM) for phase correction. The LCA we use is an amplitude-only spatial light modulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity. We measured the imaging…