Improvement of MgF2 thin coating films for laser applications

MgF2 thin films have been deposited by physical vapor deposition on different substrates (laser crystals, a saturable absorber crystal and glasses), in order to investigate the best conditions for antireflection coatings. The relevance of using these MgF2 coatings has been evidenced by different laser gain experiments performed on different coated and uncoated elements such as Nd:CGGG, Nd:LiNbO3 and Cr4+:YAG. Then the optical properties of the MgF2 films have been systematically investigated for different annealing temperatures and ion bombardment treatments. A substantial improvement in the films transmission has been demonstrated. The obtained results are correlated to morphologic changes in the MgF2 films.