A Novel Bidirectional Output Oscillating-Amplifying Integrated Fiber Laser With 2 Ports × 2 kW Level Near-Single-Mode Output

A novel bidirectional output oscillating-amplifying integrated fiber laser which combines the advantages of the bidirectional output fiber laser oscillator and the oscillating-amplifying integrated fiber laser is proposed and demonstrated experimentally. The influences of the reflectivities and center wavelengths of FBGs on the laser output power and efficiency were studied theoretically. The characteristics of the output laser were studied in detail in experiment. Based on this structure, we finally demonstrated a bidirectional laser output of 2 × 2-kW level with an active fiber length of 6 m for the oscillating section and 7 m for the amplifying section at both ends. The optical-to-optical conversion efficiency is 80.4%. The beam qualities of both ends are
${M}_{A}^{2}\sim 1.3$
and
${M}_{B}^{2}\sim 1.4$
, which indicates a near-single-mode output. To the best of our knowledge, it was the first time that this structure has been proposed, and its feasibility was demonstrated experimentally.