The fast-axis polarization instability arises in a weakly birefringent fiber as a result of competition between the natural fiber birefringence and the nonlinear ellipse rotation. Direct observation of the fast-axis polarization instability is reported. A full theoretical development of the polarization instability in a twisted, birefringent optical fiber is presented. The theory includes the derivation of and full solutions for the evolution of light in a twisted fiber as well as stability analysis and phase-plane representation of the solutions. The experiment is described in detail; good agreement is obtained between theory and experiment. As a result of the instability, very small variations in either the input power or the input polarization to the fiber result in large changes in the output polarization. A crossed polarizer at the fiber end converts the polarization variation into intensity information. Thus the modulation depth of an input pulse has been increased from 15% to 100%. Modulation gains of as much as 10 times are theoretically possible.
© 1993 Optical Society of America
Original Manuscript: December 4, 1991
Revised Manuscript: January 19, 1993
Published: July 1, 1993
Sandra F. Feldman, Doreen A. Weinberger, and Herbert G. Winful, "Polarization instability in a twisted birefringent optical fiber," J. Opt. Soc. Am. B 10, 1191-1201 (1993)