A tunable laser system emitting coherent radiation selectively variable over the range of wavelengths from about 1650 A to about 3300 A utilizes a crystal, composed of a fluoride of at least a Column IIIb metal doped with at least one trivalent ion of a lanthanide series element, and pumped with high average power pulses. The crystal is emplaced in an optical cavity having means, such as a diffraction grating, etalon, or optically-tunable prism, to vary the coherent emission wavelength.