Tao Rumao

Tolerance on Tilt Error for the Incoherent Combination of Fiber Lasers in a Real Environment

We present a detailed study on the tolerance on tilt error for the incoherent combination of fiber lasers propagating in a real environment and analyze the influence of fill factor, mechanical jitter and atmospheric turbulence on tilt tolerance. Numerical results show that the tolerance on tilt error is independent of the fill factor and decreases with an increase in mechanical jitter or turbulence intensity

Optical quality of high-power fiber laser beams propagating through collimating systems

Within the framework of the ray optics theory, the effects of heating effect and geometric aberration on optical quality of fiber laser beam are calculated and analyzed. An analytical expression for the beam quality parameter M 2 of fiber laser beam propagating through a multilens optical system is derived as a function of the system parameter. The optical quality of high-power laser beam propagating through a collimating system is investigated. It is shown that a best optical quality can be found as the laser power increases and the corresponding laser power depends on the collimating system parameter. The investigation presents a reference for the design of high-energy fiber laser collimating systems.

Propagation of high-power partially coherent fibre laser beams in a real environment

The propagation performance of high-power partially coherent fibre laser beams in a real environment is investigated and the theoretical model of a high-power fibre laser propagating in a real environment is established. The influence of a collimating system and thermal blooming is considered together with atmospheric turbulence and mechanical jitter. The laser energy concentration of partially coherent beams in the far field is calculated and analysed based on the theoretical model. It is shown that the propagation performance of partially coherent beams depends on the collimating system, atmospheric turbulence, mechanical jitter and thermal blooming. The propagation performance of partially coherent beams and fully coherent beams is studied and the results show that partially coherent beams are less sensitive to the influence of thermal blooming, which results in that the energy degeneration for partially coherent beams is only 50% of that for fully coherent beams. Both partially coherent beams and fully coherent beams become less sensitive to thermal blooming when the average structural constant of the refraction index fluctuations increases to 1.7 × 10−14m−2/3. The investigation presents a reference for applications of a high-power fibre laser system.