Optical properties and surface morphology of near infrared multilayer antireflection coatings

Abstract Theoretical and experimental studies on multilayer antireflection (AR) coatings useful in the near infrared region, covering 1200 to 2000 nm are carried out, in which the relative merits and demerits of using a low refractive index magnesium fluoride (MgF 2 ), along with a high refractive index Substance H2 (Sub2) material of E. Merck, in comparison to silicon dioxide (SiO 2 ) and Sub2, are specifically investigated. It is seen that MgF 2 together with Sub2 produces wider band antireflection coatings, with lower ripple and integrated reflection loss (IRL), R * , whereas SiO 2 /Sub2 combination produces AR coatings with medium spectral coverage, and the coatings are free of structural defects, which in turn are highly durable against adverse environmental conditions.