In-line single-mode fiber polarization controllers ar 1.55 microns, 1.3 microns, and 0.63 micron.

Single-mode fiber quarter-wave plates utilizing linear birefrigence induced by coiling the fiber in a loop are described. Optimal quarter-wave plates are obtained by one turn 0f 1.0 cm radius for 0.6328 microns light for a single-mode fiber with an outer diameter of 81 microns. For single-mode fiber with a diameter of 120 microns, optimal quarter-wave plates consist of one turn of 0.95 cm radius for 1.3 microns wavelength of two turns of 1.3 cm radius for 1.55 microns wavelength. Devices were made for cabled and uncabled fiber which provide complete polarization control by adjusting the angles of two such coils.