Polarization characterization of a Mach-Zehnder interferometer.

Polarization characterization of a Mach-Zehnder interferometer, based on the state of polarization (SOP) and power measurement at the interferometer output, is presented. We study the SOP and degree of polarization (DOP) of the output light, first as a function of the light power in each arm of the interferometer for a fixed input SOP and DOP, and second as a function of the SOP's in each arm of the interferometer for a fixed input power. Stokes formalism and the Poincaré sphere are used for simultaneous representation of the SOP and DOP, as well as their evolution. It is shown that the SOP and DOP stability and also the output light power are highly dependent on the light source coherence. Knowledge of these different parameters leads to configurations that allow simultaneous control of the SOP and DOP. We can hence realize a quasi-monochromatic nonpolarized light source, which is useful for the polarization-independent characterization of optical components.