These are some very interesting questions that do relate to understanding the universe. An unpolarized photon has no meaning in a determinate universe since every photon has a well defined polarization before any measurement.
The quantum reality is that even a single photon can be unpolarized and the measurement of a single photon polarization actually results in either of two polarizations. This cruel quantum logic limits what we can know about quantum precursors for quantum outcomes.
A photon is a quantum superposition of two polarization states and when those two polarizations share quantum phase, the photon is polarized. When the quantum phases of the two polarizations are not coherent, the photon is unpolarized. Of course, there are many degrees of depolarization just as there are elliptical as well as circular and linear polarizations.
There is a magnetic field perpendicular to the electric field and each polarization. Note that certain combinations of amplitude and polarization can result in a dark photon due to destructive interference. The question then becomes where does the photon energy disappear to?
Just like a photon can be transform limited as a sinc pulse in time and frequency, the universe is a 13.4 Byr sinc pulse in time made up of 1e125 sinc pulses of aether in frequency. So the photon Fourier transform limit also reflects the universe Fourier transform limit...