Determining the Signed High-Order Topological Charge With an Improved Mach-Zehnder Interferometer

摘要

Although the topological charge of a beam carrying an optical vortex is an important parameter, only low-order topological charge can be determined with most existing methods. We improve the Mach-Zehnder interferometer to measure the magnitude of the topological charge of Laguerre-Gaussian beam from the bright interference petals produced by the beam and its conjugate beam, and a plane mirror is used on one arm of the interferometer to produce the conjugate beam. Furthermore, the sign of the topological charge is determined by passing the beam through a triangular aperture and analyzing the diffraction field. We demonstrate that the magnitude and sign of the topological charge up to +/- 120 can be determined with this method.

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