Feature

Grazing Incidence Anti-Reflection Coatings

Jagdish C. Monga

High power dye lasers are a formidable source of tunable and coherent radiation in many scientific, industrial, and medical applications. In pulsed dye oscillators, multiple prism grating combination is generally used to get narrow linewidths and to reduce the possibility of damage to the grating surface. Since the magnification provided by the prism increases rapidly as the incidence angle approached 90°, these are used at grazing incidence angles. A serious disadvantage of these beam expanders is the reflection loss, which can be as high as 27% for a glass-air interface at 80° incidence for p-polarized radiation. Moreover, to use these beam expanders in widely tunable lasers, it is important that the reflection loss be minimized over a broad range of wavelengths. This makes the use of broadband anti-reflection coatings essential for these prism beam expanders.