“Interface-free” ultrabroadband antireflection film based on nanorod structure with continuous change in refractive index

The bandwidth and laser induced damage threshold (LIDT) are the key factors influencing the performance of broadband antireflection (AR) films in optical systems. In this study, we used glancing angle deposition (GLAD) technology to prepare an “interface free” ultrabroadband AR film with continuously varying refractive index and a nanorod structure. Owing to the changing refractive index from substrate to air, the average residual reflectivity of our AR films in the transmission band of 200–2500 nm of the entire fused quartz substrate is less than 0.55%, which is far superior to the traditional broadband AR film. Further, owing to removal of the interface and nanorod structure, the LIDTs of the ultrabroadband AR film at 1064 and 532 nm are 22.5 and 22.6 J/cm2, respectively. These are approximately 50% and 20% higher than those of the traditional 532 and 1064 nm AR film, respectively, indicating superior laser damage resistance.