Detection of multiplexing orbital angular momentum states by single objective

We proposed a simple method to detect and demultiplex multiplexing orbital angular momentum (OAM) beams with topological charges (TCs) from -32 to +32 by using specially designed hybrid phase masks and a high numerical aperture objective. Under vector diffraction condition, the phase shifting expression can be employed to modulate the three-dimensional position of focal spots which could be used to demultiplex multiplexing OAM beams. Polarization multiplexing OAM beams with TCs from -16 to +16 also could be measured and demultiplexed by encoding two spatial light modulators. This simple method has potential applications in OAM detecting and demultiplexing, polarization multiplexing OAM optical communication, optical manufacture and optical interconnects.