We report on the experimental observation of polarization splitting and terahertz oscillations in transmission and laser emission from optically anisotropic microcavities. A guest-host composite of tris-(8-hydroxyquinoline) aluminium (Alq₃) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) serves as active laser material. The anisotropy is attributed to oblique columnar structures in the distributed Bragg reflector mirrors of our microcavity, resulting from sample fabrication. A splitting of 0.2 nm occurs in the laser emission from an organic vertical cavity surface emitting laser at a wavelength of 612.6 nm, and a splitting of 2.5 nm is obtained from a sample for Ti-Sapphire laser transmission at 781 nm. Split modes are perpendicularly polarized. An upconversion setup allows temporally resolved studies of transmission and emission behavior, showing an oscillation at a frequency of 1.25 THz in transmission, and 0.18 THz in emission, respectively. The temporal behavior of laser emission is modelled by a set of rate-equations and extended to account for the resulting oscillations. Our observations suggest that a phase-coupling mechanism between both occuring modes is present in the laser emission from our microcavity.