Efficient phase locking of erbium-doped fiber ring lasers by a common ring filter

Abstract

Efficient phase locking of two erbium-doped fiber ring lasers is demonstrated by constructing a common ring filter. The ring filter offers the functions of both mode selection and mutual injection coupling between the lasers. Thanks to the mutual injection locking between them, they achieve the phase locking state and coherently combine in the far-field. Moreover, a single-mode feedback fiber is introduced to filter the far-field pattern to make the phase locking state more stable. The spatial interference fringes, output powers and spectra all indicate that employing the common ring configuration can achieve efficient phase locking of multiple fiber ring lasers.