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The performance of lithium–sulfur (Li–S) battery is strongly dependent on the sulfur electrodes materials. Due to the chemical interaction between electrodes and intermediates produced in charging and discharging process, the Janus‐polar two dimensional (2D) electrode materials can enhance the electrochemical performance of Li–S battery by overcoming shuttle effect and increasing diffusion rates. Here, it is explored the structural, electronic, and dynamic characteristics of Li ion, S8 cluster, and lithium polysulfides adsorbed over Janus Phosphorus Nitride monolayer with blue phosphorene phase (b‐PN) by using first‐principles calculations. The reported findings highlight potential of the b‐PN monolayer as a good host material, given that the large absorption energies of different clusters vary from −0.47 to −3.78 eV, which can suppress shuttle effect effectively. These strong adsorptions are origin from the chemical interaction between nitrogen atoms of the b‐PN and Li atoms in lithium polysulfides in present work. Particularly, it is predicted that b‐PN monolayer has extremely small diffusion barriers for Li ion and Li2S8 clusters of 0.10 and 0.03 eV, which leading to a higher battery charge and discharge rate than reported graphene and MoS2. It is hoped that this efficient strategy for promising host materials of sulfur‐electrode guides the development of next‐generation lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

We report on the growth and laser operation of Tm:Lu3Al5O12 (Tm:LuAG) single crystal grown via the micro-pulling-down ($\mu $ -PD) method, for the first time to the best of our knowledge. Spectral properties (absorption and fluorescence) and fluorescence lifetime of the Tm:LuAG crystal were measured at room temperature. Using a 790-nm diode laser as pump source, continuous-wave laser operation of the Tm:LuAG crystal was demonstrated with a maximum output power of 2.88 W and a slope efficiency of about 39.1% at 2016 nm. Passively $Q$ -switched laser operation was also investigated using Cr:ZnSe as saturable absorber. The maximum average output power reached about 0.53 W with the shortest pulse width of 54.3 ns and a pulse energy of $21.9~\mu \text{J}$. This letter reveals that the $\mu $ -PD technique is reliable for growing high-performance Tm3+-doped crystals for various potential applications. [ABSTRACT FROM AUTHOR]

In this letter, molybdenum ditelluride (MoTe2), a new member of the transition metal dichalcogenides family, has been characterized and fabricated as an optical modulator for the development of broadband wavelength tunable laser using a Tm3+-doped CaYAlO4crystal as a laser gain medium. The maximum average output power reaches 0.75 W with the shortest pulse width of about $0.69~\mu \text{s}$ and repetition rate of 70.9 kHz, which leads to a pulse energy of about $10.58~\mu \text{J}$ and peak power of 15.3 W. Keeping the MoTe2optical modulator inside the laser resonator and at the same time introducing an undoped YAG for wavelength tuning, wavelength tunable passively Q-switched laser operation with a wavelength range of about 112 nm has been demonstrated. This letter experimentally verifies the potential of the novel 2D material MoTe2as an optical modulator. At the same time, this letter paves the way toward the realizations of simple and compact wavelength tunable pulsed laser sources based on broadband 2D materials saturable absorbers. [ABSTRACT FROM AUTHOR]

We report on continuous-wave and passively Q-switched Tm: Y2SiO5 (YSO) crystal lasers. For continuous-wave operation, a maximum output power of 3.23 W is achieved at 1969.8 nm with slope efficiency of 34.3%. The results represent the best laser performance that ever obtained in Tm3+-doped oxyorthosilicate materials. Effective continuous-wave lasers have been also obtained at 1976.0, 1972.9, and 2044.6 nm by using differently coated output couplers. Using Cr: ZnSe saturable absorber, passively Q-switched Tm: YSO lasers are realized at 1944 and 2022 nm, for the first time to our knowledge. The maximum average output power has reached 0.74 W with pulsewidth of 78.3 ns and the corresponding pulse energy is 71.8 μJ. The present results indicate that Tm: YSO lasers could be very potential as sources for 2-μm eye safety related applications. [ABSTRACT FROM AUTHOR]

Abstract: Absorption and emission spectral properties of GdVO4 single crystal doped with Ho3+ ions were investigated at room temperature. Polarized absorption cross section is calculated in the range of 400–2200nm. Results were analyzed and parameters were calculated based on Judd-Ofelt theory, the emission spectrum shows that the emission intensity around the wavelength of 546nm associated with transition 5S2 → 5I8 is much stronger than other bands in the observed range and potentially enable the green light output around this emission band in this crystal. [Copyright &y& Elsevier]

Cr4+:YbAG (Cr4+:Yb3Al5O12) crystal with a size up to Φ24 mm×30 mm was grown by the Czochralski method. In the absorption spectrum, there are two absorption bands at 939 and 969 nm, respectively, which are suitable for InGaAs diode laser pumping, and there is an absorption band at 1030 nm, which is suitable for passive Q-switched laser output at 1.03 μm. A broad emission spectrum from 970 to 1100 nm was exhibited from 940 nm wavelength pumping. This crystal is promising as a self-Q-switched laser crystal used for compact, efficient, highly stable, passive self-Q-switched thin chip solid-state lasers. [Copyright &y& Elsevier]

Abstract: In this paper, a Yb3+ doped Lu3ScAl4O12 single crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The absorption spectrum, emission spectrum and fluorescence lifetime of Yb:Lu3ScAl4O12 crystal were measured at room temperature. The absorption bandwidth, emission bandwidth, absorption cross-section, emission cross-section and fluorescence lifetime have been estimated as 25nm, 12.6nm, 0.54×10−20 cm2, 1.47×10−20 cm2 and 1.43ms. The spectral properties of Yb:Lu3ScAl4O12 crystal were compared with those of Yb:Lu3Al5O12 (Yb:LuAG) crystal. The results indicate that Yb:Lu3ScAl4O12 crystal should be a potential candidate used for generating short pulses in mode-locking operation. [Copyright &y& Elsevier]

Here, we demonstrate the broadband spectra and efficient laser performance of a disordered Nd:Sr0.7La0.3Mg0.3Al11.7O19 (Nd:ASL) crystal. The polarized absorption and emission spectra were characterized and calculated with the Judd–Ofelt (J–O) theory, and the results show that this crystal has relatively large σ polarized absorption and emission cross sections, with peak emission cross sections of 4.5 × 10−20 cm2 at 1051 nm and an emission width of 30 nm at 1074 nm, which are favorable for pulsed lasers. The laser-diode-pumped continuous-wave (CW) and passively Q-switched lasers at 1051 nm were realized for the first time to our best knowledge. For CW laser, the maximum output power was 1.95 W with the slope efficiency of 42.6%, and for the passive Q-switching, the maximum output power was 0.73 W with the pulse width of 7.96 ns and peak power of 5.64 W. The results demonstrate that Nd:ASL crystal is a potential candidate for lasers, especially high-peak pulsed lasers such as Q-switching and mode-locking. [ABSTRACT FROM AUTHOR]

Abstract: The high optical quality Tm: YAG single crystals with dopant concentrations of 2, 4, 8 at % Tm3+ ions have been grown by the Czochralski (CZ) method .The segregation coefficients of Tm3+ ions in CZ-grown 2, 4, 8 at % doped Tm: YAG crystals determined by ICP-AES method are equal to 0.93, 1.04, 1.10, respectively. The absorption spectra in the range of 190–900nm and the IR absorption spectra in the range of 1000–4500cm-1 of the Tm: YAG crystals were also measured at room temperature. The results indicate that Tm: YAG is favorable for laser diode-pumped system, and air annealing can improve the quality of the Tm: YAG crystal. [Copyright &y& Elsevier]

Abstract Eu3+-doped Bi 4 Ge 3 O 12 (BGO) single crystal with the size of Ø2 × 83 mm3 was successfully grown by the micro-pulling-down method. The absorption cross section, emission cross section and Judd–Ofelt analysis of Eu:Bi 4 Ge 3 O 12 (Eu:BGO) were reported for the first time. The absorption cross-section is 1.03 × 10−20 cm2 with full-width at half-maximum of 3.1 nm at around 393 nm. The spectroscopic intensity parameter Ω t (t = 2,4,6), radiative transition probabilities, branching ratios and radiative lifetime were obtained, respectively. Furthermore, the stimulated emission cross-section centered at 611 nm was calculated to be 6.32 × 10−21 cm2. The fluorescence lifetime of 5D 0 level was obtained to be 1.51 ms. The results indicate that Eu: BGO single crystal could be a potential laser host in the visible range. [ABSTRACT FROM AUTHOR]

A multilayer black phosphorus, as a novel two dimensional saturable absorber, has superb saturable absorption properties for a Er:CaF 2 solid-state pulse laser. The pulse laser is realized at mid-infrared region with the passively Q-switched technology by a diode-pumping. The high-quality black phosphorus saturable absorber is fabricated by liquid phase exfoliation method. The pulse laser generates the pulses operation with the pulse duration of 954.8 ns, the repetition rate of 41.93 kHz, the pulse energy of 4.25 μ J and the peak power of 4.45 W. Our work demonstrates that black phosphorus could be used as a kind of efficient mid-infrared region optical absorber for ultrafast photonics. [ABSTRACT FROM AUTHOR]

Dy 3+ -doped YAlO 3 single crystal has been successfully grown by Czochralski technique. The spectroscopic parameters were determined by Judd-Ofelt theory based on the measured polarized absorption spectra. Dy:YAP crystal exhibits a yellow emission centered at 574 nm which can be used for pumping of the forbidden 1 S 0 - 3 P 0 ytterbium clock transition. The decay lifetime of the 4 F 9/2 level was measured to be 185 μs. [ABSTRACT FROM AUTHOR]

We report on diode-pumped Nd:LuAG crystal and ceramic lasers operating at about 1.83 μm, using a simple and compact plane-concave cavity configuration. For Nd:LuAG crystal laser oscillating at 1828.43 nm, the maximum output power reaches 0.36 W with slope efficiency of about 5.0%. For Nd:LuAG ceramic laser, a maximum output power of 0.145 W is achieved with slope efficiency of about 2.2%, and the lasing wavelength peaks at 1828.76 nm. The 1.83-μm Nd laser sources could be very promising for eye-safe applications because they have stronger water absorption than another kind of eye-safe Nd lasers operating at 1.4 μm. [ABSTRACT FROM AUTHOR]

Abstract: A diode-end-pumped passively Q-switched ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser with gallium arsenide (GaAs) wafer as saturable absorber has been realized. In the experiment, two pieces of GaAs wafers with respective thicknesses of 400 and 700 μm were used respectively. The output laser characteristics such as the pulse duration, single pulse energy and peak power, have been measured. By using thicker GaAs wafer as saturable absorber, a minimum pulse duration of 3.5ns was obtained with an average output power of 361mW and a pulse repetition rate (PRR) of 25kHz, corresponding to a single pulse energy of 19.6μJ and a peak power of 5.7kW. With a 400μm-thick GaAs wafer as saturable absorber, a maximum output power of 469 mW was achieved. The central wavelength of the laser was measured to be 1050.4nm at pump power of 7.8W and dual wavelength operation peaked at 1049.3nm and 1051.6nm was observed at a high pump power of 10W. By considering Gaussian spatial distribution and the thermal effects in the gain medium, the coupled rate equations for passively Q-switched Yb:YAG laser with GaAs saturable absorber were given. [Copyright &y& Elsevier]

High-quality Dy:PbWO 4 crystal has been successfully grown by the Bridgman method. Fluorescence properties of the grown crystal at the yellow-light region were discussed. The absorption cross-section of Dy3+ ions at 454 nm was calculated to be 0.142 × 10−20 cm2, which corresponded to the transition from 6H 15/2 to 4I 15/2 level. Based on Judd-Ofelt theory, the J-O intensity parameters Ω t and the emission cross-section were calculated. The fluorescence lifetime of 4F 9/2 level was measured to be 193 μs. • Dy: PbWO 4 crystal was grown successfully by the Bridgman method. • Judd-Ofelt theory was used to analyze the spectral properties of Dy: PbWO 4 for the first time. • Dy: PbWO 4 crystal is a potential laser medium for yellow laser operation. [ABSTRACT FROM AUTHOR]