  Transitional millisecond pulsars are systems that alternate between an
accreting low-mass X-ray binary (LMXB) state, and a non-accreting radio pulsar
state. When at the LMXB state, their X-ray and optical light curves show rapid
flares and dips, origin of which is not well understood. We present results
from our optical and NIR observing campaign of PSR J1023+0038, a transitional
millisecond pulsar observed in an accretion state. Our wide band optical
photopolarimetry indicates that the system shows intrinsic linear polarisation,
the degree of which is anticorrelated with optical emission, i.e. the
polarisation could be diluted during the flares. However, the change in
position angle during the flares suggests an additional emerging polarised
component during the flares. We also find, based on our H$_\alpha$ spectroscopy
and Doppler tomography, that there is indication for change in the accretion
disc structure/emission during the flares, possibly due to a change in
accretion flow. This, together with changing polarisation during the flares,
could mark the existence of magnetic propeller mass ejection process in the
system. Furthermore, our analysis of flare profiles in both optical and NIR
shows that NIR flares are at least as powerful as the optical ones and both can
exhibit transition time scales less than 3 sec. The optical/NIR flares
therefore seem to originate from a separate, polarised transient component,
which might be due to Thomson scattering from propeller ejected matter.
