Luminescence and lasing properties of neodymium- and uranium-activated inorganic laser liquids

An attempt was made to describe and show the possibilities of new inorganic neodynium- and uranium-activated laser liquids: SO2-GaCl3-NdCl4; SO2Cl2-GaCl3-NdCl3-UO2Cl2; POCl2-MCln-NdCl3-UO2Cl2 for development and synthesis of direct nuclear reaction-excited lasers. Luminescence data presented in the work were used to calculate the luminescence parameters of the laser liquids such as oscillator strengths f, probability of spontaneous radiation A, intermultiplet luminescence branching coefficient β, cross-section for induced radiation σ, luminescence decay time τ, quantum yield η, and others. It is shown that the oscillator strengths of the normal absorption bands of Na3+, which play the main part in the pumping processes, exceed the oscillator strengths of Na3+ for aqueous and many other nonaqueous systems. In the luminescence excitation spectra of the Na3+ ion, bands are isolated in the range 400–1000 nm atλrec =1.06 µm. With excitation, luminescence occurs through the4F3/2→4I9/2,11/2.13/2 channels. Luminescence spectral data are related to the lasing parameters. The threshold lasing energy is∼18 J/cm3. For a resonator with mirros h1=100% and h2=20, 40, 56, and 80%, the lasing energy is∼20–120 MJ/cm3 in the pumping energy range 18–180 J/cm3. The differential efficiency is ∼0.2% The substantial angular radiation divergence (θ∼4·10−2 rad) and strong thermostatic distortions that occur in the active element (dn/dT≈−1.9·10−4K−1) are a disadvantage of laser liquids. It is shown that operation of neodymium- and uranium-activated inorganic liquid lasers is stable under the present conditions.