Dynamics of a Q-switched bismuth-doped fibre laser: simulation and comparison with experiment

Abstract

Using an improved travelling wave model, we have numerically investigated the dynamics of a Q-switched bismuth-doped fibre laser. Comparison of simulation results with previously reported experimental data demonstrates good agreement of the multipeak lasing structure and the shape of the strongest pulses at various levels of pumping. We have assessed the effect of the main laser parameters on output laser characteristics and quantitatively evaluated the effects of the nonsaturable loss in the active fibre and amplified spontaneous emission on output power saturation. Based on analysis of time-dependent light intensity and gain distributions in the gain medium at different instants in time, we have formulated recommendations how to improve output laser characteristics.

[Retracted] Application of GIS and Multisensor Technology in Green Urban Garden Landscape Design

“…The three-dimensional virtual visualization system designed by the author is perfect for garden design. [20]. In this experiment, the remote sensing 5 Journal of Sensors sensor network of the landscape area consisted of 110 nodes, and the nodes were divided into an area of 110 m × 110 m. Figure 3 shows a comparison of the data transmissions used between the three different models.…”

The Dynamics of Multi-Peak Pulsed Generation in a Q-Switched Thulium-Doped Fiber Laser

“…From the data in Figures 6 and 7, it is obvious that an increase in the quality factor over time τ q ~τc in each period of the pulse-periodic mode of thulium laser with the set of parameters used in the experiment, including the AOM parameters, leads to the appearance of a peak structure of the output pulse. In [32,33], it was proposed to use an AOM with three ports [22] to obtain single pulses with increased amplitude in a bismuth laser. The point of the proposed method is that in each period, the AOM is switched on several times for a short time (for τ q << τ c ) required to reflect the traveling wave from the output mirror.…”

“…The use of such models is suitable for studying stationary generation modes, but it is impossible to correctly describe the generation dynamics on their basis. For the intensities of the traveling pump waves and the amplified spontaneous emission (ASE), the radiation transfer equations should be used, as in [22,28] for ytterbium-doped fiber lasers and for bismuth-doped fiber lasers in [32,33]. Additionally, the equations for populations should be solved at each point of the medium.…”

“…In thulium fiber lasers, which have a typical active medium length of several meters [1,4,32,34], the intermediate case is usually implemented when T q ~2T c . With such a ratio of the indicated times, it is difficult to predict the temporal structure of the output radiation in the Q-switched mode.…”