Invited:Mode Purity of Phase Structured Light Beams:Role of Spin-Orbit Coupling

Spin-orbit coupling (SOC) has been a subject of intense study during the past decade, especially when light interacts with anisotropic media. In this letter, we study perhaps for the first time the manifestation of SOC in such intrinsically anisotropic liquid crystal-based spatial light modulators (LC-SLM). Through an optical modal decomposition approach, we observe a degradation in purity when we attempt to generate azimuthally phase varying beams with orbital angular momentum (OAM). We investigate the origin of SOC in LC-SLM through spatially-resolved Stokes polarimetry and observe a polarization inhomogeneity in the generated beam. Upon a deeper investigation, we find that the polarization inhomogeneity also results in a geometric phase, which further confirms the role of SOC in the generation of the structured light beam. Finally, we suggest a potential pathway to circumvent this problem and achieve structured light beams with enhanced modal purity. http://dx.doi.org/10.1364/ao.XX.XXXXXX