Circular polarization of light refers to the specific orientation of the electric field vector as the light propagates. In right circular polarization (RCP), the electric field vector rotates in a clockwise direction when viewed in the direction of propagation. In left circular polarization (LCP), the electric field vector rotates counterclockwise when viewed in the direction of propagation.
To produce circularly polarized light using a polarizer, you need a combination of a polarizer and a retardation plate (also known as a quarter-wave plate). Here's a step-by-step explanation:
Start with unpolarized light or linearly polarized light.
Pass the unpolarized or linearly polarized light through a polarizer. The polarizer transmits light that oscillates in a specific direction, aligning the electric field in one direction and blocking the perpendicular component.
The linearly polarized light that passes through the polarizer is incident on a retardation plate, which is typically made of a birefringent material like quartz. The retardation plate introduces a phase shift of a quarter-wavelength (90 degrees) between the two orthogonal polarization components of the incident light.
The quarter-wave plate converts the linearly polarized light into circularly polarized light. The plate achieves this by retarding one polarization component by a quarter-wavelength and leaving the other unchanged. This phase shift causes the electric field vector to rotate.
The orientation of the retardation plate determines the handedness of circular polarization. If the fast axis of the retardation plate aligns with the direction of the polarizer, right circularly polarized light is produced. If the fast axis is perpendicular to the direction of the polarizer, left circularly polarized light is produced.
By adjusting the angle between the polarizer and the retardation plate, you can control the intensity of the circularly polarized light.
It's worth noting that circularly polarized light can also be generated naturally through certain processes, such as the emission of light from certain sources or the interaction of light with chiral molecules.