Design and Preparation of 1064 nm Notch Filter

According to the current laser protection requirements of human eyes and visible-near-infrared photodetectors, the design method and fabrication technology of a 1064 nm notch filter were studied. Based on the equivalent refractive index theory, considering the optimization of spectrum and field intensity distribution, the notch filter of a quarter film composed of SiO₂/Y₂O₃/H4 and the notch filter of a non-quarter film composed of SiO₂/H4 were designed. The notch filter was fabricated by ion beam-assisted thermal evaporation deposition, and its optical and anti-laser damage properties were tested. The results show that matching the antireflection film on both sides of the film structure of G|(0.5LH0.5L)^s|A can effectively reduce the passband ripple, and adjusting the thickness of the outermost layer of the film system can improve the spectral characteristics and electric field intensity distribution of the film system at the same time. The average transmittance of the plated notch filter of quarter film at the 400~900 nm and 1200~2000 nm bands is 89.98% and 93.21% respectively, the transmittance at 1064 nm is 1.29%, and the laser damage threshold is 6.0 J/cm²; the average transmittance of the notch filter of the non-quarter film is 93.70% and 94.99% at 650~900 nm and 1200~2000 nm bands respectively, the transmittance at 1064 nm is 1.60%, and the laser damage threshold is 6.8 J/cm².