LBO晶体上1064 nm,532 nm二倍频增透膜的设计及误差分析

采用矢量合成法设计了LiB3O5(LBO)晶体上1064 nm,532 nm二倍频增透膜,在1064 nm处的反射率为0.0014%,532 nm处的反射率为0.0004%。根据误差分析,薄膜制备时沉积速率精度控制在 6.5%时,1064 nm处的反射率增加至0.22%,532 nm处增加至0.87%。材料折射率的变化控制在 3%时,1064 nm处的反射率达0.24%,532 nm处达0.22%。沉积速率和折射率控制的负变化不增大特定波长处的剩余反射率。与膜层折射率相比,薄膜物理厚度对剩余反射率的影响小。低折射率膜层的厚度变化对特定波长处的剩余反射率影响最明显,即为该膜系的敏感层。为改善膜基之间的附着力,选择Y2O3或SiO2作为过渡层,从过渡层的厚度匹配和膜层的折射率匹配两方面进行了相应的膜系匹配设计。

Design and Error Analysis of 1064 nm, 532 nm Frequency-Doubled Antireflection Coating for LBO

1064, 532 nm frequency-doubled antireflection coating was designed on LiB3O5(LBO) substrate using vetor addition method. The design result showed that the reflectance could be 0.0014% at wavelength of 1064 nm and 0.0004% at 532 nm. Based on error analysis, the reflectance increased to 0.22% at 1064 nm and 0.87% at 532 nm when the precision of deposition rate was controlled to be +6.5%. If the refractive index accuracy was +3%, the reflectance at 1064 nm reached 0.24% and 0.22% at 532 nm. It was found that the negative variance of the deposition rate and refractive index would not cause the increase of the reflectance at 1064 nm and 532 nm. The refractive index had more effect on the reflectance than the thickness. The variation of the lowest refractive index layer′s thickness had an obvious effect on the reflectance, that is to say it was the sensitive layer of the coating design. To improve the adhesion between the coating and substrate, Y2O3 or SiO2 was selected as transition layer and gave the corresponding coating design according to the thickness and refractive index match.