LaTiO_3薄膜的光学及激光损伤特性

Optical Properties and Laser Damages of LaTiO_3 Coatings

研究了工艺条件（沉积温度、真空度、蒸发束流）对LaTiO3薄膜光学和激光损伤特性的影响。采用椭偏法测量了薄膜的光学常数,分析了不同工艺条件下制备薄膜的折射率和消光系数,得出工艺参数与薄膜光学性能的相互关系。研究结果表明,当沉积温度从室温（未加热）升高到220℃,所制备薄膜的折射率从1.9334增大到1.9644（d光）。当真空度从6.5×10-3（未充O2）降低到2.0×10-2Pa时,薄膜的折射率从1.9726下降到1.9268。随着束流从75增加到140 m A,薄膜的折射率从1.9337到1.9548略微有所增加。在所研究的工艺参数范围内,薄膜的折射率基本稳定,消光系数均小于1.74×10-3,尤其当沉积速率低于0.44 nm/s时,所制备薄膜的消光系数优于10-6。LaTiO3薄膜的激光损伤形貌随制备工艺而不同,其激光损伤阈值约为16.2~18.8 J/cm2（1064 nm,10 ns）。

The LaTiO3 thin films were synthesized by electron beam evaporation on quartz glass substrate.The influence of the deposition conditions, including the substrate temperature, pressure and deposition rate, on the optical properties and laser damage of the LaTiO3 coatings was investigated with ellipsometry. The results show that the gTowth conditions sig- nificandy affect the optical properties and laser-induced damage threshold,and that the refractive index of all coatings was fairly stable with an extinction coefficient below 1.74 × 10-3. For example,an increase from room temperature to 220℃ erhanced the refractive index from 1.9334 to 1.9644;an increase of pressure from 6.5 ×10-3 Pa （oxygen-free） to 2.0× 10-2 Pa reduced the refractive index from 1.9726 to 1.9268;and an increase of deposition current from 75 to 140 mA raised the refractive index slowly from 1.9337 to 1.9548. Grown at a rate lower than 0.44 nm/s,the extinction coefficient was letter than 10-6.Depending on the growth conditions,the laser-induced threshold is about 16.2- 18.8 J/cm2.