High-power, high-energy ultrafast fiber lasers are vital instruments in many domains, ranging from industrial processing to basic and applied scientific research.
Diagram of Coherent Beam Combining Experimental Setup Image Credit: Shuangxi Peng, Zhihao Wang, Feilong Hu, Zhengyan Li, Qingbin Zhang, Peixiang Lu
However, the power/energy expansion of a single fiber laser amplifier is always limited by nonlinear effects and thermal effects. To further achieve power/energy scaling and surpass the limitations of a single fiber laser amplifier, Coherent Beam Combination (CBC) technology is a useful tactic.
Multiple laser beams can overlap and interfere with one another when they have a stable phase relationship and mutual coherence. With this method, average power and pulse energy can be increased by a factor that is nearly equal to the total number of combined channels.
However, as the number of beam-combining channels rises, so does the complexity of CBC systems, which can have unfavorable effects on the system, such as reduced beam-combining efficiency, deteriorated beam quality, and more operational challenges.
Utilizing filled aperture coherent beam combining technology, researchers from Huazhong University of Science and Technology have developed an ultrafast fiber laser system with an average power output of 403 W, 0.5 mJ pulse energy, and 260 fs. Good power stability (RMS < 0.5%) was maintained while achieving excellent beam quality (M2 < 1.2).
Effective compensation for the incomplete compensation of high-order dispersion following grating compression has been accomplished by employing integrated electronic dispersion hardware, allowing for both superior improvements in pulse quality and optimization of the pulse width.
Furthermore, the average power used by CBC for each channel is more than 230 W, which reduces operational complexity and difficulty. It is anticipated that in the future, power and pulse energy can be raised to the kw and mJ levels, respectively, with only four channels of coherent synthesis.
Journal Reference
Peng, S., et al. (2024) 260 fs, 403 W coherently combined fiber laser with precise high-order dispersion management. Frontiers of Optoelectronics. doi.org/10.1007/s12200-024-00107-5