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In the present work we have synthesized a novel composite materials based on praseodymium (Pr) doped LaCaBO (LCBO: Pr) nanocrystallites embedded into the polymethylmethacrylate (PMMA) and polycarbonate (PC) matrices for laser operated devices. It was shown that the SHG is very sensitive to the wavelength of external light.The optimal content of the LCBO: Pr nanocrystallites sized within the 30-110 nm range was equal to 5.7 wt%. It was shown that the SHG is very sensitive to the wavelength of external photoinducing illumination. [ABSTRACT FROM AUTHOR]

We have found that BiB3O6:Tm3+ glass nanoparticles (NP) incorporated into the polymethylmethacrylate (PMMA) and polycarbonate (PC) polymer matrices additionally treated by dc-electric field (at electric strength about 8 kV/cm) at temperatures above the glassing temperature of the polymers show promising values of electrooptics coefficients (up to 10 pm/V at λ = 633 nm). It was established that only during incorporation into the highly polarized PC matrices one could observe an enhancement of the electroopitcs effect (EOE) coefficient with increasing time of the dc-electric treatment. The main increase was observed for all the samples at times higher than 80 min of dc-electric field treatment at temperature above the glassing temperatures of the corresponding polymers. The most striking feature is the achievement of effective electrooptics coefficient value below than 10 pm/V (λ = 633 nm) for the 4% content of the Tm doped BiBO glass nanoparticle (NP) embedded in the PC matrix. In the case of the bulk glasses the thermal poling unambiguously shows that the achieved maximal values of the electrooptics coefficient did not exceed 3.2 pm/V for 0.5% Tm+3 concentration. [ABSTRACT FROM AUTHOR]

We have revealed that lanthanum calcium borate (La2CaB10O19) crystals show two-photon absorption (TPA) favored by UV laser field. UV-induced TPA measurements were performed under illumination of a Xe-F laser (λ = 217nm) as a photoinducing (pumping) beam. This pumping laser beam created a thin surface layer (about 85 nm) that was a source of the observed photoinduced TPA. Use of the longer photoinducing wavelength leads to a substantial decrease of the photoinduced TPA. The performed DFT calculations of the band energy dispersion clearly show that the effect observed is due to specific band energy dispersion between the sub-bands. The Raman shifted Nd-YAG laser radiation (λ = 1.9 μm) as well as its second and fourth harmonics (λ = 950 and λ = 475 nm, respectively) were used as fundamental (probing) beams of the TPA. The highest values of the TPA β coefficient were achieved for polarization of the pumping light directed along the second-order crystallographic axis. The obtained values of TPA coefficients are higher than for BiBO crystals that were also investigated by us. [ABSTRACT FROM AUTHOR]

The up-conversion of infrared radiation at 808 nm, emitted by a diode laser, into blue emission centered at 480 nm in 1 at.% Tm, 5 at.% Yb: YVO4; 1 at.% Tm, 8 at.% Yb: YVO4 and 2 at.% Tm, 5 at.% Yb: YVO4 has been studied. The highest intensity of blue emission is found for the 1 at.% Tm, 8 at.%Yb: YVO4 system. The power dependence of up-converted emission upon continuous-wave excitation as well as the time evolution of its intensity upon short-pulse excitation were found to be consistent with a two-step excitation mechanism in which the forward Tm3+–Yb3+ energy transfer is followed by the back Yb3+–Tm3+ energy transfer. The effect of dopant concentrations on the up-conversion process is interpreted taking into account dynamics of the excited states involved. [ABSTRACT FROM AUTHOR]

Crystals of YVO[sub4]:Ho were grown by the Czochralski method. The structure of the low-energy levels of Ho&sup3+; has been estimated experimentally. Intensity parameters, radiative lifetimes, and branching ratios have been calculated in the framework of the Judd-Ofelt theory. The influence of temperature on luminescence lifetimes has been investigated. The calculated nonradiative transition rate was compared with the energy-gap law. The potential laser gain for the &sup5;I[sub7]-&sup5;I[sub8] transition has been estimated. [ABSTRACT FROM AUTHOR]

Abstract. Laser oscillation around 1.6 micro m was realised at room temperature for low-doped Er:YVO[sub 4] crystals (0.5 at % and 1 at %) as well as for Er(1 at %), Yb(5 at %):YVO[sub 4] crystal in continuous-wave mode. The maximum slope of the input-output curve was about 19% (vs. absorbed power) for Er(0.5 at %):YVO[sub 4]. The laser oscillation was discretely tunable in the spectral range between 1531 and 1604 nm. [ABSTRACT FROM AUTHOR]

The optical properties of Yb[sup 3+] ions excited by energy transfer from Nd[sup 3+] ions in LiTaO[sub 3] :Nd, Yb crystals are presented. The emission band of Yb[sup 3+] ions is broad, due to the strong phonon-coupling and to the relative large Stark-splitting of the ground [sup 2] F[sub 7/2] multiplet. The emission cross-section was evaluated by the reciprocity method, and a value of 0.53×10[sup -20] cm[sup 2] was obtained. The gain coefficients derived for the inversion parameters in the range 0.05 to 0.5 indicate positive gain in the 985–1070 nm range. [ABSTRACT FROM AUTHOR]