Maxim E. Doroshenko

Efficient laser based on CaF 2 -SrF 2 -YbF 3 nanoceramics

CaF(2)-SrF(2)-YbF(3) fluoride ceramics of high optical quality was prepared, and its absorption, fluorescence, and laser oscillation properties were investigated. Oscillation slope efficiency that was only a few percent lower than that for a single crystal of similar composition was demonstrated under diode pumping.

SrF2:Nd3+ laser fluoride ceramics

SrF(2):Nd(3+) fluoride ceramics of high optical quality was prepared and its spectroscopic and laser properties investigated. Oscillations of different optical centers depending on the excitation wavelength were obtained with a slope efficiency of up to 19%.

Laser and self-Raman-laser oscillations of PbMoO 4 :Nd 3+ crystal under laser diode pumping

Different regimes of laser operation and stimulated Raman scattering (SRS) for a laser diode (LD)-pumped PbMoO4:Nd3+ crystal have been investigated. Under 1.5 W LD pumping, the output power of the PbMoO4:Nd3+ laser in the free-running mode at 1056 nm reached 0.65 W with a slope efficiency of up to 53%. Using different LiF: F-2 saturable absorbers, we achieved a maximum pulse energy of 11 microJ at a 1.4 ns pulse duration and a maximum output power of 0.35 W (10 microJ) at a 7 ns pulse width in the passively Q-switched mode. PbMoO4:Nd3+ self-Raman-laser operation at 1163 nm (first Stokes) was obtained for the first time, to our knowledge. The self-Raman-laser output pulse energy was measured to be as high as 6 microJ and the pulse duration was estimated to be shorter than 500 ps.

Diode-pumped Er:CaF 2 ceramic 2.7 μm tunable laser

Spectroscopic and laser properties of a newly developed high optical quality Er:CaF2 hot-formed ceramic were investigated. Under pulsed 968 nm laser diode pumping, the mid-infrared (2.7 μm) radiation was obtained with a slope efficiency of 3%. Laser tunability was reached using a birefringent filter and the laser tuning range of 118 nm, from 2687 up to 2805 nm, was demonstrated. The maximal output energy reached was 0.48 mJ at 2730 nm for the absorbed pumping energy 34 mJ.

Multiphonon relaxation rates measurements and theoretical calculations in the frame of non-linear and non-Coulomb model of a rare-earth ion-ligand interaction

The fluorescence kinetics decay from 3F3, 3H5, 3H4, 3F4 multiplets of Tm3+ and 5F5, 5I5, 5S2 + 5F4, 5I6, 5I7 multiplets of Ho3+ ions in Y3Al5O12, Lu3Al5O12 and LiYF4 crystals was directly measured. On the basis of these measurements the multiphonon relaxation (MPR) rates of the transitions were determined. The theoretical dependence of multiphonon relaxation rates on the rare-earth ionic radii was derived using the non-linear (NL) theory of multiphonon relaxation. A good qualitative agreement of this dependence with new and earlier measured MPR rates in rare-earth ions in the row from Tm3+ to Pr3+ in YAG, YLF, and LaF3 crystals was obtained. The dependence of multiphonon relaxation rates on the crystal type is also considered.

Demonstration of high self-Raman laser performance of a diode-pumped SrMoO4:Nd3+ crystal.

Passively Q-switched self-Raman laser oscillations in the SrMoO4:Nd3+ crystal optically pumped by a laser diode (LD) at 804 nm are demonstrated for the first time to our knowledge. Output parameters of LD-pumped SrMoO4:Nd3+ laser were investigated in free-running, passively Q-switched, and self-Raman regimes of laser operation, over a wide range of pulse repetition rates (8.5-85 kHz). A pulse energy of 21 microJ was measured in the self-Raman regime at 1163 nm (first Stokes) wavelength, which is 6 times higher than that for the GdVO4:Nd3+ self-Raman laser of similar design.

First ceramic laser in the visible spectral range

Results for new fluoride ceramics doped with praseodymium ions in which, to the best of our knowledge, for the first time a laser in the visible spectral range (639 nm) was obtained under GaInN blue laser diode optical pumping. In our experiments, CW operation with lasing threshold less than 100 mW of absorbed pump power and slope efficiency exceeding 9% was realized.

Cooperative quenching: experiment, theory and Monte-Carlo computer simulation

Abstract An analytical expression and results of Monte-Carlo computer simulations are proposed for the kinetics of cooperative static quenching decay in crystals with arbitrary acceptor concentration and arbitrary multipolarity of interaction process S =6, 8, 10, which at a long decay time can be approximated by the nonexponential law I ( t )exp[−( wt ) k ], where k =0.41, 0.3, 0.25 for multipolarities S =6, 8, 10, respectively. The phenomenon of cooperative energy transfer from single Nd 3+ , Tm 3+ or Ho 3+ ion simultaneously to the pair of Ce 3+ ions and from single Er 3+ ion to three Ce 3+ ions with, respectively, two and three times smaller transition energy each in highly concentrated La 1− x Ce x F 3 crystals is presented. The influence of overlap integral (between donor ion and cooperative pair and triple Ce 3+ acceptor) and electronic matrix elements of donor transitions on the cooperative energy transfer rate for a set of donor ions is discussed.

Dysprosium-doped PbGa2S4 laser excited by diode-pumped Nd:YAG laser.

We realized a compact mid-IR room temperature operating Dy(3+):PbGa(2)S(4) laser, excited by a diode-pumped Nd:YAG laser at a wavelength of 1318 nm. The pumping laser was operating in pulsed mode with a pulse length of 4 ms and repetition rate of 20 Hz. Maximum pumping energy at a wavelength of 1318 nm was 15 mJ. Energy up to 90 μJ and mean output power of 1.8 mW was obtained at a wavelength of 4290 nm with a slope efficiency with respect to absorbed pumping energy better than 3%.

Cooperative nonradiative cross-relaxation in crystals of La(1−x)CexF3 solid solutions

The phenomenon of concentration quenching of the luminescence from donor ions in crystals of La1−xCexF3 solid solutions was studied. A cooperative nonradiative energy transfer from a single excited neodymium ion to a cooperative acceptor representing a couple of cerium ions, as well as from a single erbium ion to three cerium atoms (also forming a cooperative acceptor center), was observed.