Transformation of the ytterbium laser spectrum with pulsed selective pumping

Abstract

The Yb-doped crystals and glasses present promising active media for high power lasers. These media are typical of broad gain linewidths -- near 10 nm for Yb:YAG and 100 nm for glasses. The experiments have been performed on pumping Yb- doped YAG and glass samples in a cavity by Nd:YAG laser at 0.94 micrometer. The pumping intensity was 105 divided by 106 W/cm2, stored energy density, 1 - 2 J/cm3. For Yb:YAG simultaneous oscillations have been produced at transitions near 1.03 and 1.05 micrometer. The spectral width for both bands reached 3 nm. There was established a competitive character of lasing at these transitions displayed in opposite amplitude modulation of the corresponding oscillation envelopes. The laser spectrum transformation using the interconnection of 1.03 and 1.05 micrometer transitions is discussed. When pumping the Yb-doped silicate glass there were registered the spectra near 1.03, 1.04 and 1.06 micrometer with the total width over 40 nm. A method of the laser spectrum transformation based on the stored energy transfer over inhomogeneously broadened emission line is proposed for Yb glasses. The expected range of the spectrum transformation makes several tens of nm, the transfer rate 103 - 104s-1. The obtained results are of interest for the creation of pulse-repetitive laser sources with the spectrum varying from shot to shot.