Lasing properties of new Nd~(3+)-doped tungstate, molybdate, and fluoride materials under selective optical pumping

摘要

The purpose of this work was to determine the relative efficiencies of new Nd~(3+)-doped laser active/Raman -tungstate, molybdate, and fluoride - materials (SrWO_4, PbWO_4, BaWO_4, SrMoO_4, PbMoO_4, SrF_2, and LaF_3) under selective longitudinal optical pumping by the alexandrite (～ 750 nm), or diode (～ 800 nm) laser. Crystals with various length, orientations and active ions concentrations were tested. To optimize the output of the tested lasers a set of input dichroic and output dielectric mirrors with different reflectivities were used. For realized lasers operating at pulsed free-running regime, threshold energy, slope efficiency, emission wavelength, and radiation polarization were determined. For each crystal, fluorescence lifetime and absorption coefficient under given pumping were established. The slope efficiency in case of Nd~(3+):PbMoO_4 laser at wavelength 1054 nm was measured to be 54.3% with total efficiency of 46% which is the best result obtained for all new tested crystals. For Nd~(3+) doped SrWO_4, PbWO_4, and BaWO_4 crystals simultaneous laser and self-Raman emission were demonstrated in Q-switched regime. Thus newly proposed laser Raman crystals demonstrate high efficiency for Nd~(3+) laser oscillations comparable with well known and widely used Nd:KGW crystal. Further improvement in the quality of tungstate and molybdate type crystals should result in further increase in lasing efficiency at 1.06 μm wavelength. Self Raman frequency conversion of Nd~(3+) -laser oscillations in these crystals should result in high efficient pulse shortening, high peak power and new wavelengths in 1.2 - 1.5 μm wavelength region.