Theoretical model and numerical study of effect of target reflected light on high-power fiber laser

<sec>In a high-power fiber laser system, the reflected light generated when hits target may be recoupled to and amplified by laser, thereby damaging system. This situation is particularly serious for such as spectral beam combining high power which lacks effective light-return protection. In order solve above problems, it necessary integrate various physical effects in whole system link, evaluate analyze influence of on operating state so optimize optical path layout structure beginning design avoid unnecessary losses. Based atmospheric transmission theory, rate equation medium heat conduction model, effect analyzed. this paper conducted numerical simulation coupling efficiency laser. It found that under certain conditions, related distance, offset angle axis, divergence angle, center position beam, will affect output power, quality factor, thermal signal-to-noise ratio stimulated Raman scattering spectrum The has maximum value at distance. For example, up 140 W obtained distance 1500 m, largely affected axis far less than increases from 500 m 2000 m. change 0.1 can 0.11° 0.44°. also shown changes 0 15<i>''</i>, decays nearly exponentially with angle. close 1% near 12<i>''</i>, almost negligible. light. Deterioration lead deterioration quality. As enters increases, forward decrease backward signal increase, increase rapidly end. When present, caused selecting gain different pump absorption coefficients are very important. (SRS) rejection decreases coefficient. SRS 5 dB coefficient 1.5 dB/m 4.5 dB/m, resulting reduce reliability system.</sec><sec>In test systems lasers, attention should paid entire process, includes outer internal comprehensive constraints multiple key indicators analyzed, probability damage or degradation due evaluated. research results guiding significance suitable parameters optimizing energy system.</sec>