polarizationcontrol

Polarization control refers to the manipulation of the polarization state of light or other electromagnetic waves to achieve a desired orientation and phase relationship among electric field components. Controlling polarization is essential in many optical systems, where the state of polarization affects coupling efficiency, detector response, interference visibility, and nonlinear interactions.

Methods can be classified as passive or active. Passive components include linear polarizers, wave plates (quarter-wave and half-wave), and polarization-maintaining fibers that preserve a chosen state. Active devices include electro-optic modulators such as Pockels cells, Faraday rotators, and liquid crystal rotators, which alter polarization under applied electric fields, often at high speed. Fiber-based polarization control uses polarization controllers and dynamic polarization scramblers to compensate for drift.

The physics framework includes Jones calculus for fully polarized light and Mueller calculus for partially polarized light. Performance is described by metrics such as extinction ratio, degree of polarization, and polarization mode dispersion in fibers. Stability is challenged by temperature, mechanical stress, and optical power.

Applications span optical communications using polarization-division multiplexing, laser systems requiring fixed or rapidly tunable polarization, polarization-sensitive imaging and spectroscopy, ellipsometry, polarimetry, and quantum information experiments that rely on well-defined polarization states.

Limitations include insertion loss, bandwidth limitations, and the need for calibration. Advances focus on broadband retarders, low-loss modulators, and compact MEMS-based rotators. See also terms such as Jones calculus, Mueller calculus, and polarization-maintaining fibers for related concepts.