  The light curves of optical outbursts observed in blazar OJ287 during
1983-2015 are analyzed and model-simulated to investigate the nature of its
optical radiation. It is shown that the December/2015 outburst has its
multi-wavelength variability behavior very similar to that of the synchrotron
outburst in March/2016, indicating that the 2015 outburst may originate from
synchrotron process. In combination with helical motion of superluminal
components, the precessing jet nozzle scenario previously proposed is used to
model-simulate the lightcurves of all the optical outbursts discussed. The
optical light curves for both periodic and non-periodic outbursts observed in
blazar OJ287 can be well interpreted in terms of lighthouse effect due to the
helical motion of superluminal optical knots, showing their common origin in
synchrotron process. A coherent and compatible framework is tentatively
suggested to understand the entire phenomena in OJ287. The double-peak
structure of the periodic outbursts might be explained by invoking the
cavity-accretion flare models for comparable-mass binary systems in eccentric
motion.
