Abstract

This paper models the dynamics resulting from the use of a birefringent optical fiber as the nonlinear element in the external cavity of an additive-pulse mode-locked laser. Most previous researchers of this problem have taken a scalar approach that assumes that the state of polarization is preserved in the fiber. We build on their work by using a simplified laser model;¹ however, we use the full nonlinear theory to model the evolution of the state of polarization in a birefringent fiber. We investigate the effects of nonlinear pulse shaping obtained with a highly birefringent fiberand the effects of the fast-axis polarization instability that arises in a weakly bire-fringent fiber.² In either case the birefringence has a significant effect on the dynamics of the laser system.

© 1990 Optical Society of America