Search

The absorption and emission spectra of LiTaO3:Tm3+ crystals for Tm3+ laser transition near 1.9 micro-m are discussed. The absorption cross sections for the (super 3)H(sub 6) - (super 3)H(sub 4) transition, emission cross section for the (super 3)F(sub 4) - (super 3)H(sub 6) transition and game curves are determined for specific inversion parameters. It is shown that the broad absorption band and high absorption cross section at about 795 nm are suitable for laser diode pumping.

Influence of lithium tetraborate (Li2B4O7, TBL) glass matrix on the luminescent properties of the Pr+3 ions emission was investigated. It was demonstrated that the decrease of matrix long-range ordering leads to substantial widening of corresponding peaks in the emission spectra in comparison with crystalline Ca4GdO(BO3)3 matrices. During the decrease of temperature from 292 down to 82 K a distinct low-energy spectral shift of the principal red luminescent band from 607 to 610 nm is observed, which is a consequence of a coexistence of several structural borate fragments. Simulations of incorporation the Pr3+ ions into the TBL glasslike matrix were carried out using the Langevin molecular dynamics simulations and quantum chemical simulations. Possibility of partial substitution of boron ions by Pr3+ ions is demonstrated. The contribution of the electron-phonon subsystems to the spectral broadening of the corresponding emission red lines was evaluated. It was shown that the main contribution to the emission bands gives harmonic electron-phonon interactions contrary to the generally adopted model assuming prevailing role of anharmonic electron-phonon interactions. [ABSTRACT FROM AUTHOR]

Conversion of the infrared (IR) radiation at 975 nm into the visible emission in the Czochralski grown YVO4 crystals containing several different concentrations of Yb3+ and Ho3+ has been investigated. Unlike other matrices doped with ytterbium and holmium, the YVO4:Yb,Ho system exhibits intense red upconverted emission originating from the 5F5 level, whereas, green upconverted emission originating from the 5S2 level of Ho3+ is found to be unusually weak at room temperature but dominating at 4.2 K. Power dependencies of the emissions are consistent with two-step excitation process but time dependencies differ and imply that the longlived 5I7 level of Ho3+ is involved in the second-step excitation of red emission. Intensity distribution of σ-polarized emission band associated with the 5F5-5I8 transition with peak value of effective stimulated emission cross section amounting to 10-20 cm2 combined with the possibility of tailoring of optical pumping efficiency by appropriate choice of dopant concentrations offer a potential of IR-pumped visible laser emission. [ABSTRACT FROM AUTHOR]

Influence of lithium tetraborate (Li2B4O7, TBL) glass matrix on the luminescent properties of the [Pr.sup.+3] ions emission is investigated. It is demonstrated that the decrease of matrix long-range ordering leads to substantial widening of corresponding peaks in the emission spectra in comparison with crystalline Ca4GdO(BO3)3 matrices.

The conversion of the infrared (IR) radiation at 975 nm into the visible emission in the Czochralski grown YVO4 crystals containing several different concentrations of Yb(super 3+) and Ho(super 3+) is investigated. An explanation of the mechanisms involved in the excitation process and at the assessment of laser potential associated with upconverted red emission is given.