Definition of polarized light
The asymmetry between the direction of vibration and the direction of propagation is called polarization, and it is the most obvious sign that the shear wave is different from other longitudinal waves. Only the shear wave has polarization. Light waves are electromagnetic waves, so the direction of light wave propagation is the direction of electromagnetic wave propagation. The electric vibration vector E and the magnetic vibration vector H in the light wave are both perpendicular to the propagation velocity v, so the light wave is a transverse wave and it has polarization. Polarized light is called polarized light.