  We study the optical flux and polarization variability of the binary black
hole blazar OJ 287 using quasi-simultaneous observations from 2015 to 2023
carried out using telescopes in the USA, Japan, Russia, Crimea, and Bulgaria.
This is one of the most extensive quasi-simultaneous optical flux and
polarization variability studies of OJ 287. OJ 287 showed large amplitude, ~3.0
mag flux variability, large changes of ~37% in degree of polarization, and a
large swing of ~215 degrees in the angle of the electric vector of
polarization. During the period of observation, several flares in flux were
detected. Those flares are correlated with a rapid increase in the degree of
polarization and swings in electric vector of polarization angle. A peculiar
behavior of anticorrelation between flux and polarization degree, accompanied
by a nearly constant polarization angle, was detected from JD 2,458,156 to JD
2,458,292. We briefly discuss some explanations for the flux and polarization
variations observed in OJ 287.
