Passively Q-switched 1617-nm polycrystalline ceramic Er:YAG laser using a Cr:ZnSe saturable absorber

Abstract

methane in the atmosphere, the 1617-nm transition is more promising for applications which need long-distance propagation in free space than the 1645-nm transition [2,3].YAG crystal is used as the most common laser gain host because of its unique thermomechanical properties. Er:YAG crystal lasers have been demonstrated both in continuous-wave and Q-switched modes [1][2][3][4][5]. In 2007, a single-crystal Er:YAG which yielded a continuous-wave (CW) output power of 31 W was demonstrated at 1617 nm with a slope efficiency of 47 % with respect to incident pump power [3]. In 2011, an actively Q-switched 1617-nm single-crystal Er:YAG laser with pulse energy up to 30.5 mJ and pulse duration of <20 ns at 20 Hz repetition rate has been reported [4]. However, the conventional crystals cannot be made in large scale or fabricated composite with a complicated configuration to enhance the laser performance [6]. As a novel laser medium, the polycrystalline ceramics are advantageous over single crystals in many aspects, such as rapid and large volume fabrication, flexibility in doping concentration and profile, and low cost. With the development of the ceramic fabrication technology, the Er:YAG ceramic laser has been reported to have similar laser efficiency and spectroscopic parameters to those of the single crystals [7][8][9]. In 2010, a composite Er:YAG ceramic laser generated a quasi-CW output power of 6.8 W at 1645 nm and the corresponding slope efficiency of 56.9 % with respect to the absorbed pump power. In the next year, Zhang et al. [10][11][12] reported a 1617-nm Er:YAG ceramic which yielded an output power of 14 W corresponding to a slope efficiency of 51.7 % with respect to the incident pump power. In the Q-switched mode, the laser performance of the Er:YAG ceramic laser has been reported by using graphene as saturable absorber. However, the graphene Q-switched lasers typically have pulse durations of the order of microseconds. To get short pulse Abstract We report on a passively Q-switched polycrystalline ceramic Er:YAG laser by using a Cr:ZnSe crystal as a saturable absorber. When pumped by a 1532-nm Er-, Yb-doped fiber laser with the maximum power of 12.4 W, the laser yielded pulses of 28.8 ns duration at 1617 nm by using a saturable absorber with an initial transmission of 80 %. The corresponding peak power was up to 11.3 kW at a repetition rate of 2.17 kHz. The dependence of the pulse duration and repetition rate on the pump power was experimentally studied. The numerical and experimental results both show that the pulse duration was mainly determined by the initial transmission of the saturable absorber and slightly affected by the transmission of the output coupler. At last, we give some prospects for further narrowing down the pulse duration.

High‐Energy Density Li‐Ion Capacitor with Layered SnS2/Reduced Graphene Oxide Anode and BCN Nanosheet Cathode

“…This can be ascribed to the sp 3 CS bond between the RGO and SnS 2 nanosheet. [30,31] The new CS bonds can also be demonstrated by band at higher binding energy of S 2p observed in SnS 2 , and these results are consistent with FTIR analyses. [32] Figure 3e shows the highresolution Sn3d spectrum of samples SnS 2 and SnS 2 /RGO.…”

“…However, the XPS peaks of S 2p in the SnS 2 /RGO shifted to higher binding-energy region compared to the pure phase of SnS 2 , and this result may be ascribed to the CS bound in composites. [31] Taken in consideration of Sn 3d band of SnS 2 which was also found to shift to higher binding-energy side ≈0.4 eV with respect to SnS 2 /RGO (Figure 3e), the phenomenon can be explained by electron transfer between SnS 2 and RGO nanosheets because of their different electron concentrations. [34] Therefore, the bonding Adv.…”

Remarkable Improvement in Photocatalytic Performance for Tannery Wastewater Processing via SnS2 Modified with N‐Doped Carbon Quantum Dots: Synthesis, Characterization, and 4‐Nitrophenol‐Aided Cr(VI) Photoreduction

“…SnS 2 nanosheets were prepared according to a process reported with some modifications. [57] In a typical experiment, SnCl 4 and thioacetamide (TAA) at a molar ratio of SnCl 4 :TAA = 1:3 were mixed and dissolved in 70 mL distilled water under vigorous stirring to form a homogeneous solution at room temperature. Subsequently, the obtained solution was transferred to a Teflon-lined stainless-steel autoclave, which was subjected to reaction at 463 K for 6 h. Finally, the resultant was collected by centrifugation, washed with water and ethanol several times, and dried at 60 °C for 12 h for further characterization and synthesis of N-CQDs/SnS 2 catalysts.…”

Green Synthesis of a Metal‐Free 0D/2D Heterojunction: A Cost‐Effective Approach

“…Besides, the intensity‐average lifetime (<τ>) of the emission decay is also calculated and found to be 5.32 ns and 1.04 ns for GCN and CD 7 /GCN, respectively. The chance of a non‐radiative pathway from the electronic interaction between the carbon dots and the GCN nano sheets could be inferred from the notable decrease in the emission lifetime of the heterojunction . The related electron‐transfer rate constant (k et ) in CD 7 /GCN is calculated to be 7.73 X 10 8 S −1 using Equation …”

“…The chance of a non-radiative pathway from the electronic interaction between the carbon dots and the GCN nano sheets could be inferred from the notable decrease in the emission lifetime of the heterojunction. [24] The related electron-transfer rate constant (k et ) in CD 7 /GCN is calculated to be 7.73 X 10 8 S À 1 using Equation (2). [25]…”