β\beta-BaB2_2O4_4 deep UV monolithic walk-off compensating tandem

The generation of watt-level cw narrow-linewidth sources at specific deep UV wavelengths corresponding to atomic cooling transitions usually employs external cavity-enhanced second-harmonic generation (SHG) of moderate-power visible lasers in birefringent materials. In this work, we investigate a novel approach to cw deep-UV generation by employing the low-loss BBO in a monolithic walkoff-compensating structure [Zondy {\it{et al}}, J. Opt. Soc. Am. B {\bf{20}} (2003) 1675] to simultaneously enhance the effective nonlinear coefficient while minimizing the UV beam ellipticity under tight focusing. As a preliminary step to cavity-enhanced operation, and in order to apprehend the design difficulties stemming from the extremely low acceptance angle of BBO, we investigate and analyze the single-pass performance of a $L_c=8$mm monolithic walk-off compensating structure made of 2 optically-contacted BBO plates cut for type-I critically phase-matched SHG of a cw $\lambda=570.4$nm dye laser. As compared with a bulk crystal of identical length, a sharp UV efficiency enhancement factor of 1.65 has been evidenced with the tandem structure, but at $\sim-1$nm from the targeted fundamental wavelength, highlighting the sensitivity of this technique when applied to a highly birefringent material such as BBO. Solutions to angle cut residual errors are identified so as to match accurately more complex periodic-tandem structure performance to any target UV wavelength, opening the prospect for high-power, good beam quality deep UV cw laser sources for atom cooling and trapping.Comment: 21 pages, 8 figures, to appear in Opt. Commu

LiGaSe2 optical parametric oscillator pumped by a Q-switched Nd:YAG laser

Optical parametric oscillation is demonstrated for the first time with the chalcogenide nonlinear crystal LiGaSe2 pumped by a nanosecond Nd:YAG laser. Angle tuning provides coverage of the 4.8–9.9 μm spectral range in the mid-IR by idler pulses

Optical pump-probe processes in Nd 3+ doped KPb2Br5, RbPb2Br5, and KPb2CI5

Recently, laser activity has been achieved in the low phonon energy, moisture-resistant bromide host crystals, neodymium-doped potassium lead bromide (Nd{sup 3+}:KPb{sub 2}Br{sub 5}) and rubidium lead bromide (Nd{sup 3+}:RbPb{sub 2}Br{sub 5}). Laser activity at 1.07 {micro}m was observed for both crystalline materials. Laser operation at the new wavelengths 1.18 {micro}m and 0.97 {micro}m resulting from the {sup 4}F{sub 5/2}+{sup 2}H{sub 9/2} {yields} {sup 4}I{sub J} transitions (J=13/2 and 11/2) in Nd:RPB was achieved for the first time in a solid state laser material. In this paper we present cw pump-probe spectra in order to discuss excited state absorption, reabsorption processes due to the long lived lower laser levels as well as possible depopulation mechanisms feasible for more efficient laser operation in these crystals. The bromides will be compared with potassium lead chloride (Nd{sup 3+}:KPb{sub 2}Cl{sub 5})

Radiation-stimulated processes in SrMgF4 single crystals irradiated with fast electrons

Large single crystals of SrMgF4 (SMF), grown by the Bridgman method, were studied (T = 7–350 K, E = 1.2–6.2 eV) for both the pristine unirradiated and irradiated by an electron-beam (Ee = 10 MeV, D = 100–160 kGy, Φmax = 5 × 1015 electrons/cm2) SMF-crystals. The optical absorption spectra at different radiation doses were determined. The luminescence spectra were studied upon excitation with visible/ultraviolet light (PL), or X-ray radiation (XRL). The PL excitation (PLE) spectra under UV-radiation, the temperature dependence curves for the luminescence intensity of steady-state XRL and PL recorded monitoring emission at different energies, as well as low-temperature thermoluminescence were studied. The paper discusses the effect of electron-beam irradiation on the optical and luminescence properties of SMF crystals, the temperature dependence of the luminescence intensity and low-temperature thermoluminescence of irradiated SMF crystals. © 2021 Elsevier B.V.Nuclear Physics, NPSiberian Branch, Russian Academy of Sciences, SB RAS, (RFMEFI62119X0022)Ministry of Education and Science of the Russian Federation, Minobrnauka, (FEUZ-2020-0060)Ministry of Education and Science of the Republic of Kazakhstan, (AP08855672)Ural Federal University, UrFUFunding text 1: The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project № FEUZ-2020-0060 ), the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant № AP08855672 ). All the crystals examined were grown in framework of the state assignment of IGM SB RAS. The X-ray excited measurements were performed at the shared research center SSTRC based on the VEPP-4—VEPP-2000 complex at Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences (Novosibirsk, Russia) using equipment supported by project RFMEFI62119X0022 . The authors are grateful to A.Yu. Sofronova and M.N. Sarychev (UrFU) for assistance with low-temperature measurements.Funding text 2: The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project № FEUZ-2020-0060), the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant № AP08855672). All the crystals examined were grown in framework of the state assignment of IGM SB RAS. The X-ray excited measurements were performed at the shared research center SSTRC based on the VEPP-4—VEPP-2000 complex at Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences (Novosibirsk, Russia) using equipment supported by project RFMEFI62119X0022. The authors are grateful to A.Yu. Sofronova and M.N. Sarychev (UrFU) for assistance with low-temperature measurements

Time-Resolved Luminescence Spectroscopy of Pure and Doped with Ce3+ ions SrAlF5 Crystals

The results of a study of time-resolved photoluminescence (PL) and energy transfer in both pure and doped with Ce3+ ions SrAlF5 (SAF) single crystals are presented. The time-resolved and steady-state PL spectra in the energy range of 1.5-6.0 eV, the PL excitation spectra and the reflectivity in the energy range of 3.7-21 eV, as well as the PL decay kinetics were measured at 8.8 and 295 K. The lattice defects were revealed in the low temperature PL spectra (emission bands at 2.9 and 4.5 eV) in the undoped SAF crystals. The luminescence spectra of the doped Ce3+:SAF crystals demonstrate a new selective emission bands in the range of 3.7-4.5 eV with the exponential decay kinetics (τ ≈ 60 ns at X-ray excitation). These bands correspond to the d-f transitions in Ce3+ ions, which occupy nonequivalent sites in the crystal lattice. © 2010 Pleiades Publishing, Ltd.This work was supported by the RFBR (grants Nos. 07-02-00442; 07-02-12015; 09-02-00493)