We present the development of novel coatings for the far and extreme ultraviolet (FUV-EUV). In the EUV above ~50
nm, the strong absorption of materials has precluded the development of narrowband coatings. An extensive research has
been performed on the search and characterization of new materials with low absorption; the lanthanide series has been
found to be a source of materials with relatively low absorption in the range of interest. The discovery of a wealth of
materials with relatively low EUV absorption is basic to develop efficient multilayers, particularly with narrowband
properties. In this way, we have developed multilayers based on Yb, Al, and SiO with narrowband performance in the
50-92 nm range; these are first narrowband coatings peaked above 70 nm. Our recent research on multilayers based on
Eu, Al, and SiO provide promising results, with an increase in the peak reflectance versus Yb/Al/SiO multilayers, along
with a peak wavelength that can be extended up to ~100 nm.
For applications where FUV-EUV narrowband coatings have not been able to be prepared, we can design multilayers
that address specific purposes, such as maximizing the reflectance ratio at two wavelengths or bands. Our first goal in
this direction is the development of coatings with high 102.6 nm/ 121.6 nm reflectance ratio. Calculations predict that a
high reflectance at Lyman β with a good rejection at Lyman α can be obtained through multilayer coatings. We are at the
beginning of experimental research for this goal.