Fabrication and performance evaluation of 1 064, 532 nm frequency-doubled antireflection coating for LBO crystal

Two different types of 1 064, 532 nm frequency-doubled antireflection coatings for X-LBO were deposited by electron beam evaporation. One stack is substrate /ZrO2/Y2O3/Al2O3/SiO2/air, and the other is substrate /Al2O3/ZrO2/Y2O3/Al2O3/SiO2/air. The main difference between the two was the presence of alumina interlayer, and the optical behavior and adhesion between film and LBO substrate were investigated. Both coatings showed good optical performance that the reflectance of the coatings at 1 064 nm or 532 nm is less than 0.5%, but the coating with alumina interlayer showed stronger adhesion after annealing at 473 K for 2 h by contrast with that without alumina interlayer, which indicated that the alumina interlayer helped the coating resist the strong thermal stress from the thermal expansi