Dual-longitudinal-mode CW self-sweeping operation in Er-doped fiber laser

A new type of sweeping operation-dual-mode continuous-wave (CW) self-sweeping-is demonstrated in an erbium-doped fiber laser with a sweeping range of 2.8 nm in a region of 1605 nm. The laser generates two adjacent longitudinal modes of equal intensity, but at some moments of time, one of the modes with lower frequency begins to vanish and a new one with even higher frequency starts to grow. As a result, the self-sweeping of lasing frequency with CW intensity dynamics is observed.