Broad band emitting color centers in lithium fluoride films for optical microcavities

We have fabricated for the first time different optical microcavities made of two Bragg mirrors sandwiching a lithium fluoride film treated by low-energy electrons to create color centers. Among the so-formed defects, we focused our attention on the F-2 centers, which can be optically excited around 450 nm and give rise to an efficient broad-band luminescence centered at similar to 670 nm in the red spectral range at RT. We have modified the design of the upper reflector of the microcavities in order to shift their resonant wavelength from lambda(res)approximate to665 nm to lambda(res)approximate to640 nm. We get evidence of the different optical behaviors from measurements of the photoluminescence spectra of the radiation emitted perpendicularly to the multilayer surface.