Polarization Maintaining PM Fiber Patch Cables

:: What Is Polarization?

A polarized lightwave signal is represented by electric and magnetic field vectors that lie at right angles to one another in a transverse plane (a plane perpendicular to the direction of travel). Polarization is defined in terms of the pattern traced out in the transverse plane by the electric field vector as a function of time.

:: Polarization Coordinate System

An explicit coordinate system must be specified in order to unambiguously describe a state of polarization. This is shown in the following illustration.

The z-axis is horizontally oriented in the direction of propagation of the light. The y-axis is vertically oriented pointing up, and the x-axis is horizontally oriented to form a right-handed rectangular coordinate system. Angles are measured with reference to the x-axis, a positive angle indicating the sense of rotation from the x-axis toward the y-axis.

In the following illustration, unpolarized light is filtered by a polarizer to produce horizontal linear light. A quarter-wave retarder is used to resolve the horizontally polarized light into two equal-intensity components that travel at slightly different speeds. For the retarder orientation shown, light emerging from the retarder is right-hand circularly polarized, as seen in the right side illustration.