ERBIUM-DOPED FIBER COMPOUND-RING LASER WITH A RING FILTER

A new all-fiber, diode-pumped laser with a compound-ring structure has been demonstrated. A double-coupler fiber ring filter formed by two i n-line low-loss couplers is used as an intracavity mode selection elem ent. It functions as a filter which provides a larger free spectral ra nge for the compound laser cavity and serves as a ready port for the l aser output. The fiber laser is pumped at 980 nm with a threshold of 7 .9 mW and a slope efficiency of 0.11. The condition for an maximum out put power can he obtained by tuning an in-line polarization controller .