Tunable Transition-Metal-Doped Solid State Lasers

Transition-metal-doped solid state lasers appear to be quite useful as broadly tunable and powerful sources of coherent infrared radiation. The electronic energy levels of transition ions such as Ni, Co, V, and Fe in such hosts as MgF2, MgO, ZnF2, MnF2 and KMnF3 are strongly coupled to the lattice and have broad vibronic sidebands in both the absorption and emission spectra. The first demonstration of laser action on the vibronic sidebands of the electronic levels of divalent Ni impurity ions in MgF2 was by L. F. JOHNSON [1] and coworkers in 1963. In the initial studies [2] of the Ni:MgF2 laser, tuning over discontinuous segments in the range 1.62 to 1.84 μm was demonstrated using a lamp-pumped crystal cooled by flowing liquid oxygen. The output of this laser consisted of short spikes, the result of undamped relaxation oscillations.