L-band tunable multiwavelength fiber laser using an unpumped polarization maintaining an erbium-ytterbium double-clad fiber-loop mirror

Abstract

An L-band tunable multiwavelength source is newly proposed and demonstrated employing an unpumped polarization maintaining an erbium-ytterbium codoped double-clad fiber (PM-EYDF) loop mirror in a semiconductor optical amplifier-based fiber-ring laser. This is achieved by only adjusting the polarization controller in the loop mirror for the birefringence of the PM-EYDF, which is polarization dependent, and which originates from the fact that the traversing signal with a different polarization state absorbed by the PM-EYDF changes its effective birefringence. A similar behavior also happens when the traversing signal power is varied. The multiwavelength operation with the tunable range as large as the comb spacing of the transmission spectrum of the PM-EYDF loop mirror is successfully accomplished.