Optical vortex rotation and propagation from a spiral phase plate resonator with surface reflective coating

A spiral phase plate resonator (SPPR) is created by depositing a reflective coating on the surfaces of a single conventional spiral phase plate (SPP) for the first time to the best of our knowledge. Optical transmission through the SPPR on the output plane of the device is measured to give sharp Fabry-Perot resonances as a function of beam roll angle. Similar measurements are performed for the reflected light emerging from the input plane of the SPPR device. Varying the light frequency going into the SPPR changes the orientation of the angular pattern (Fabry-Perot resonances) to give the rotational constant of the device, in agreement with theory. The optical mode profile is measured after the beam has propagated beyond the plane of the SPPR device while remaining in the diffraction near field, thus revealing new features in the transmitted optical beam. These new results have important implications for developing the SPPR for microscopy, imaging, angle measurement, rotational scanning, and LiDAR. (C) 2020 Optical Society of America