  Recently, we have used, pulsar polarisation datasets, on circular
polarisation degree & linear polarisation position angle, to relate with well
established theories, on ellipticity parameter and linear polarisation position
angles, accrued by unpolarised photons, while undergoing photon-ALP
oscillations, inside a magnetised medium. This has given us parameter values
such as ALP mass and its coupling to photons. To further test this, we now
switch to different wavebands, other than earlier 21 cm wavelength, and check
for the validity of our model. Here we use two data sets on circular
polarisation degree of identical pulsars observed in two different wavebands.
We show, correlation between these two new sets of data and our model using the
composite product variable of ALP mass and its coupling to photons, exist. We
also check whether our model hypothesis that one physical effect, namely
ALP-photon mixing is sufficient to, estimate ALP parameters, faithfully, or
not. We conclude by describing other pertinent physical effects that may be
included into our model to explain the circular polarisation degree of pulsars,
independent of its operating wavelength of observation.
