Monolithic Rare Earth Doped PTR Glass Laser, Phase II

The main goal of the project is to demonstrate the feasibility of a monolithic solid state laser on the basis of PTR glass co-doped with luminescent rare earth ions. The main feature of this new complex material is its ability to be simultaneously an active laser medium and a phase photosensitive medium. That way the same piece of material can be used as laser gain element and a monolithic laser resonator produced by the recorded in that volume Bragg gratings (VBGs). A series of PTR glasses co-doped with rare-earth ions (Nd, Yb and Er) was fabricated. It was shown that those glasses possess both high efficiency of luminescence and photosensitivity (photo-thermo-induced change of refractive index). A technology of the recording of volume Bragg gratings in each of these new PTR glasses was developed and controllable diffraction efficiency between 10 and 99% was demonstrated. A laser was demonstrated in Nd-doped PTR glass plate using an external Fabry-Perot resonator based on two plane dielectric mirrors with longitudinal pumping by laser diodes at 808 nm. Lasing and narrowing of spectrum down to ~20 pm is demonstrated when one of the mirrors was replaced by a high efficiency VBG.