| Abstract [eng] |
This work aims to determine the most suitable technology and its parameters for the production of high-reflectivity multilayer dual-wavelength dielectric mirrors, which would be adapted to the market of medical laser manufacturers. The need for the development and improvement of such mirrors arises from the prevailing trends in the global photonics market, i.e. in order to ensure the requirements of spectral and laser resistance values and their repeatability in the case of mass production. During the research, 4 mirrors with different coating designs and technologies were produced to evaluate losses based on reflection, transmittance, absorption and scattering measurements to select the most suitable ones for further development of the experiment. It was found that the best result in terms of the spectrum was achieved for mirrors that were produced with Ta2O5 and SiO2 materials, forming only the upper layers of HfO2 by e-beam technology (99.2%), and the highest scattering losses were shown by IBS technology mirrors that were coated only with HfO2 and SiO2 materials (3.81%). Knowing that the scattering directly depends on the surface roughness, the roughness of all substrates was evaluated by various methods and the aim was to discover the main factors that lead to the increased scattering. In order to eliminate the resulting losses, the roughness of monolayer coatings was also studied. It was found that SiO2 has the greatest influence on the surface roughness in monolayers, so in the next stage, the most optimal parameters of the coating process were searched to ensure the lowest roughness of this material. In a further step, the laser resistance of the mirrors was investigated in the hope that the mirrors would meet the values required by the manufacturer of medical lasers. The best LIDT values were shown by IBS mirrors made with Ta2O5+HfO2 and SiO2 (9.24 +0.1/-0.6 J/cm2), but still did not meet the requirements given by the client in this research phase. In the last phase of the research, the mirror manufacturing process was repeated with the most optimal parameters found in the course of this research. The reflection coefficient has been improved from 99.2% to 99.5%, and according to damage probability measurements, the probability of laser damage to the coating decreased by more than 2 times compared to the primary coating process. Since the targeted laser resistance values were still not achieved at this step, the work requires extension and further development and improvement of the coating process. |
