Polarization-state control schemes for heterodyne or homodyne optical fiber communications

In heterodyne or homodyne optical fiber communications, the fluctuation of the polarization state in the fiber may deteriorate the receiver sensitivity. This paper reviews the principles and features of six polarization-state control schemes so far proposed, including two new attempts, one using Faraday rotators and the other using rotatable fiber cranks (RFC´s), both of which have been proposed very recently. Experiments simulating actual optical heterodyne receivers are also described.