Optical image rotation based on orbital angular momentum decomposition and combination

This paper theoretically presents an optical image rotation system based on orbital angular momentum (OAM) manipulation. This system consists of two parts corresponding to OAM decomposition and OAM combination functions. OAM decomposition transforms the optical field into the OAM spectrum by log-polar transformation. OAM manipulation is applied on the OAM spectrum plane of the system, and then the OAM combination transforms the manipulated spectrum back into an optical image. By applying a linear phase shift modulation to the OAM spectrum, the image rotates due to the modulation. This paper demonstrates that the OAM spectrum manipulation for image rotation is equivalent to the one-dimensional movement of one of the optical elements. It is suggested that the rotation angle adjustment of an optical image rotation system can be realized, not only by the rotation of the elements, but also made possible by the linear translation of the optical elements. This means that the OAM dimension can bring new features to optical design.