Tunable optical gain in the near uv using F+ centers in CaO

A tunable amplification around 3600 Å has been demonstrated at low temperatures in the low-energy side of the emission band of CaO crystals doped with F+ centers. The pumping power was delivered by a pulsed nitrogen laser and the optical gain was measured in a coaxial configuration. The observed amplification fits the equations of the pumping cycle for this system reasonably well. The possibility of designing a tunable laser using this material is discussed in light of our experiments.