Abstract
For spectral beam combining, an experimental system of dynamic beam quality caused by the thermal deformation of a grating has been designed and established. According to the theoretical model established, the distribution of the temperature field, as well as the thermal deformation of the grating, has been analyzed. Further, the combined beam quality and the intensity distribution have been numerically calculated in detail. The results show that the maximum temperature and the grating thermal deformation increase with the extension of irradiation time, resulting in side lobes appearing in the intensity distribution. In the experiment, the measured combined beam quality factor Mx2 was 1.29 without the thermal deformation. When the grating was heated by pump lasers at different times, Mx2 can arrive at 1.34, 1.37, and 1.41, respectively. The results reveal that the combined beam quality increases with the increase in irradiation time and changes rapidly at the beginning of heating, consistent with the theoretical analysis. The discussion and analysis of the dynamic beam quality are potentially valuable for reducing the influence of thermal deformation on the beam quality.
Highlights
Spectral beam combining (SBC) technology is a well-established method for high-radiance lasers, which has a broad application prospect in optical sensing, laser medical treatment, and spectral analysis [1,2,3,4,5,6,7,8]
Yang et al presented the influence of multilayer dielectric grating thermal deformation on the SBC system and the beam quality of the combined beam degraded with increasing incident laser-beam power density [17]
The maximum grating with a substrate material is mainly composed of SiO2, and thermal deformation of the grating surface under different laser the relief structure made of Al is selected for thermal deformation irradiation times is shown in Figure 11, including the substrate analysis
Summary
Spectral beam combining (SBC) technology is a well-established method for high-radiance lasers, which has a broad application prospect in optical sensing, laser medical treatment, and spectral analysis [1,2,3,4,5,6,7,8]. The beam quality factor is one of the key technical indexes to evaluate the beam quality in the SBC system It can be influenced by many factors, such as the spectral line width, the disturbance of the laser array, and the dispersion characteristics of the grating [9,10,11,12]. As the powers of the laser array are increased, the grating thermal deformation, which induces degeneration of the combined beam quality, becomes more significant [13,14,15]. Yang et al presented the influence of multilayer dielectric grating thermal deformation on the SBC system and the beam quality of the combined beam degraded with increasing incident laser-beam power density [17]. To our best knowledge, the correspondence between irradiation time and the dynamic change of the beam quality has not been found, which is necessary to further understand the dynamic change of beam quality so as to provide a method to reduce thermal deformation and improve the quality of the combined beam
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