Abstract

Since the introduction of single-mode DFB fibre lasers with UV induced phase-shift, these lasers have found many applications within optical communication [1]. Single polarisation operation of the laser could be attributed to a polarisation dependence of either the grating reflectivity, background loss, erbium gain, or the phase-shift. It has been shown that a birefringent distributed phase-shift causes a considerable difference in the magnitude of the phase-shift experienced by the two polarisations [2]. However, until now it has not been clarified which polarisation dependent effect is dominating in obtaining single polarisation operation. In this paper, we present experimental evidence that a birefringent distributed phase-shift is the dominating effect.

© 1998 IEEE