Single-longitudinal-mode narrow-linewidth fiber laser of single-point injection-type active parallel sub-chamber

The invention discloses a single-longitudinal-mode narrow-linewidth fiber laser of single-point injection-type active parallel sub-chamber. The fiber laser comprises: a star coupler possessing an NxN port, a fiber active sub-chamber, N-1 fiber passive sub-chambers and a seed laser, wherein two ends of the fiber active sub-chamber are connected with the two ends of a shunt of the star coupler so as to form a closed loop; the two ends of the each fiber passive sub-chamber are connected with the two ends of one residual shunt of the residual shunts of the star coupler respectively so as to form the closed loops respectively; a gain amplification unit, a mode selection unit and a 1x2 coupler are connected in one closed loop; an input terminal of the 1x2 coupler and one output terminal are connected into the closed loop respectively, and the other output terminal is taken as the output terminal of the fiber laser; the output terminal of the seed laser is connected with the fiber active sub-chamber through a seed l