What is the difference between collimating, waveguiding, attenuating, and polarizing? What's the difference between collimating, waveguiding, attenuating, and polarizing? Are they related on any level at all?
 A: The polarization of an EM wave means the direction of the E- and H-fields associated with that wave, and how they evolve with time.
"Polarizing" as a process means controlling the polarization of the wave. This could mean ensuring the wave is linearly polarized, but it could also mean ensuring it is circularly polarized or in any other state of polarization.
Polarizing can be done with many different devices, including polaroid films, wave plates, Brewster's angle windows, reflective surfaces, etc.
"Attenuating" means to reduce the power of a wave. It is only related to polarizing in that some polarizing devices operate by attenuating the components of the wave that are in different polarization from the desired output polarization.
"Waveguiding" means to transfer a wave along a structure that doesn't allow the wave to diverge (to propagate in directions other than along the waveguide). It is only related to polarizing in that many waveguides will selectively guide one polarization or another, and may propagate different polarizations at different velocities.
"Collimating" means to form a wave into a low-divergence beam propagating in free space. There is no specific relationship between collimation and polarization, though it is possible to design a device or set of optics that performs both collimation and polarization.
