Real-time OAM cross-correlator based on a single-pixel detector HOBBIT system.

The creation and detection of spatial modes of light with transient orbital angular momentum (OAM) properties is of critical importance in a number of applications in sensing and light matter interactions. Most methods are limited in their frequency response as a result of their modulation techniques. In this paper, a new method is introduced for the coherent detection of transient properties of OAM using a single pixel detector system for the creation of an OAM spectrogram. This technique is based on the ideas utilized in acousto-optic based optical correlators with log-polar optical elements for the creation and detection of higher order bessel beams integrated in time (HOBBIT) at MHz data rates. Results are provided for beams with time varying OAM, coherent combinations, and transient scattering by phase objects.