Study On The Coherent Beam Combination Technology Of Slab-solid Laser And Fiber Laser

As the application of laser technology become more and more popular, the high-power and high-quality laser beams are more in need. The slab-solid laser and fiber laser are two popular lasers because of their own Characteristics. However, because of the heat effect and nonlinear effect, it become more and more difficult to increase the output power of single laser. Therefore,the coherent beam combination which can acquire both high-power and high-quality laser output have been paid much attention to. This paper studied two coherent beam combination environments: the laboratory environment and the true atmosphere environment. Based on the two environments, we analyzed some effect facts of the CBC, successfully achieved the coherent beam combination of two and four slab-solid lasers in laboratory environment, and accomplished the aim experiment of single laser and CBC experiment of three and seven lasers in atmosphere environment. Specifically, the main contents are as follows:The far field intensity distribution computational mode has been derived based on the Fraunhofer diffraction theory. Subsequently, the common evaluation indicators of beam quality has been introduced in their definition, computational method, relative merits and range of application. By simulation, the relationship of beam quality between single beamlet and its combination was achieved. The results showed that the relationship between single Zernike aberration and factor β of coherent combination fit this expression:2 2b ?1+As, and the relationship between the average of factor β of single laser and the factor β of their combination was this:2 2( 1) 1aveb =h b - +.Then, the effect of filling factor on far field intensity distribution and correction of piston and tip/tilt error has been analyzed by way of theory and simulation. The results indicated that the filling factor affect the far field distribution by space modulation factor, and for different filling factor and apertures, if the piston was corrected below 0.08λ and the tip/tilt was corrected below 0.25λ/q, the 80% of best PIB would be achievedThe CBC experiment of two rectangular beams with SPGD algorithm and active segmented mirror has been carried out, and the performance index has been increased by 1.6 times. The experimental results, especially the system bandwidth, have been analyzed. The experimental platform of two and four slab-solid lasers has been built. On the platform, the beam quality factor β was decended to 2.5 by beam clean technique. And then, the coherent combination of two and four cleaned slab-solid lasers has been accomplished. The peak intensity of two slab-solid laser has been increased from 900 to 1589, and from 1250 to 2175 for four lasers.The work principle of AFOC and PZT-Phase modulation made by ourselves has been introduced, and tested their performance at the same time. Based on the two devices, the two stage experiments of coherent beam combination based on TIL has been carried out, that was tip/tilt correction of single laser and both tip/tilt and phase correction of multiple lasers. As to the experiment of tip/tilt correction of single laser, the two dimensional and three dimensional target has been aimed at using SPGD algorithm. The results showed that the correction error was less than 6% for two dimensional target and 10.8% for three dimensional target, which was within the range of theory value. Furthermore, the experiment of aiming at moving target with low speed has been accomplished. We found that a higher aim precision will be get with a lower gain coefficient, and a faster target can be aimed with a larger perturbation and gain coefficient. Based on the aim experimental platform of single laser, we carried out the experiment of both tip/tilt and phase correction of multiple lasers, and succeded in phase locked and tip/tilt correction of three and seven fiber lasers in the target place which was 200 meters away. The signal of PD indicated that the bandwidth of three lasers was about 20 Hz, while seven lasers was about 10 Hz.It has been proved both in theory and experiment in this paper that more attention should be paid to the beam quality of single laser and filling factor because of their high effect on the CBC,and the CBC technology was a good way to achieve output laser with both high output power and high beam quality in both laboratory and atmosphere environment.