Phonon-Terminated Optical Masers

The characteristics of phonon-terminated coherent oscillation associated with ${\mathrm{Ni}}^{2+}$, ${\mathrm{Co}}^{2+}$, and ${\mathrm{V}}^{2+}$ ions in rutile and perovskite fluorides are described. Continuous tunability over portions of the vibronic continuum of ${\mathrm{Ni}}^{2+}$ in Mg${\mathrm{F}}_2$ has been demonstrated. The system has been thermally tuned in discontinuous segments over a total wavelength span from 1.62 to 1.80 μ, the longest continuous segment being 250 Å (82 ${\mathrm{cm}}^{-1\mathrm{}}$). Alternatively, a frequency-selective element (prism) has been used to vary the oscillation frequency (at a fixed temperature of 85°K) in discontinuous segments between 1.62 and 1.84 μ. The discontinuities are a consequence of structure present in the vibronic continuum of ${\mathrm{Ni}}^{2+}$ in Mg${\mathrm{F}}_2$. Continuous-wave oscillation has been obtained from ${\mathrm{Ni}}^{2+}$ ions in Mg${\mathrm{F}}_2$ and Mn${\mathrm{F}}_2$, requiring, respectively, less than 65 and 240 W of power into a tungsten lamp. Both systems display continuous spiking, and the spectral distributions of maser emission may be very complex.