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For the first time, we present a passively Q-switched 1060 nm Nd:GSAG laser using a two-dimensional molybdenum disulfide (MoS2) nanosheet as saturable absorber. We investigate in detail the output characteristics of this laser such as average output power, pulse repetition rate, pulse width, pulse energy, and pulse peak power. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate for the first time a doubly Q-switched pulsed laser, using a novel Nd:Gd0.69Y0.3NbO4 mixed crystal and acousto-optical (AO) Q-switch and Cr4+:YAG saturable absorber. Compared to purely AO Q-switched lasers, the simultaneous use of AO Q-switches and Cr4+:YAG saturable absorbers provides the generation of a shorter pulse. We investigated in detail the output characteristics of pulsed Nd:Gd0.69Y0.3NbO4 lasers. [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate for the first time a doubly Q-switched 1,066 nm pulsed laser using a novel Nd:Gd0.69Y0.3TaO4 mixed crystal. Compared to purely acousto-optical (AO) Q-switched, the simultaneous use of AO Q-switch and Cr4+:YAG saturable absorber can provide the generation of shorter pulses. We investigate the pulsed laser performance at two modulated repetition rates of 10 and 20 kHz. [ABSTRACT FROM AUTHOR]

We demonstrate a diode-pumped acousto-optically (A-O) Q-switched 1,066 nm laser with a novel Nd:Gd0.69Y0.3TaO4 mixed crystal. At a modulation repetition rate of 10 kHz and an absorbed pump power of 15 W, the pulsed laser output characteristics are: average output power 2.41 W, pulse width 27.2 ns, pulse energy 241 μJ, and pulse peak power 8.86 kW. At a modulation repetition rate of 20 kHz and an absorbed pump power of 15 W, the characteristics are: average output power 2.68 W, pulse width 30.1 ns, pulse energy 134 μJ, and pulse peak power 4.45 kW. [ABSTRACT FROM AUTHOR]

We demonstrate for the first time a Cr4+:YAG passively Q-switched 1066 nm pulse-burst laser under 879 nm direct pump with a novel Nd:Gd0.69Y0.3NbO4 crystal. The output laser characteristics with different pump repetition rates and different Cr4+:YAG initial transmission are studied. Without the Cr4+:YAG, we obtain a maximum output energy of 2.55 mJ at an absorbed pump energy of 5.79 mJ with the highest 48% slope efficiency. The pulse-burst laser contains a maximum of 7 pulses for a Cr4+:YAG initial transmission of 55% and a pump repetition rate of 1 kHz. The single-pulse energy and narrowest pulse width reach 160 μJ and 5.5 ns at 38.2 kHz, with a peak power of 32 kW. [ABSTRACT FROM AUTHOR]

In the present work, we investigated the mechanical properties (including hardness, fracture toughness, brittleness index and yield strength) of Nd0.03Gd0.93Y2.04Sc2Ga3O12 (Nd:GYSGG) laser crystal using Vickers microhardness tester, for the first time. The defects morphology of Nd:GYSGG crystal were investigated by using chemical etching method with phosphoric acid etchant. The absorption spectrum of Nd:GYSGG from 300 to 2800 nm was measured at room temperature and the absorption peaks were assigned. The fluorescence lifetime of the 4F3/2→4I11/2 transition of Nd3+ in GYSGG is fitted to be 221.3 μs. The three Judd-Ofelt intense parameters Ω2, 4, 6 were calculated to be 0.329 × 10−20 cm2, 2.761 × 10−20 cm2 and 4.222 × 10−20 cm2, respectively. All these demonstrate that Nd:GYSGG crystal is a good candidate laser material. [ABSTRACT FROM AUTHOR]

We demonstrate a high-peak-power and narrow pulse mid-infrared (MIR) laser with xenon-lamp pumping and La3Ga5SiO14 (LGS) Q-switching on the Cr,Er:YAP crystal grown by Czochralski method. X-ray powder diffraction and x-ray rocking curves suggest the crystal has high crystalline quality. Segregation coefficients of the Cr3 + and Er3 + in the as-grown Cr,Er:YAP crystal are 4.96 and 1.07, respectively. The absorption and fluorescence spectra indicate that the Cr,Er:YAP crystal is a promising material for MIR laser by xenon-lamp pumping. The fluorescence lifetimes of the upper (I11/24) and lower (I13/24) laser levels are 0.86 and 3.57 ms, respectively. A maximum energy of 632 mJ is acquired at 5 Hz by xenon lamp pumping. By the LGS electro-optic Q-switching technology, single pulse energy of 148.6 mJ is achieved at 5 Hz with a pulse width of 35.4 ns and peak power of 4.2 MW. The results show that the LGS Q-switched Cr,Er:YAP crystal pumped by xenon lamp possesses potential application as a short-pulse and high-energy laser device. [ABSTRACT FROM AUTHOR]

• 2D MoS 2 and WS 2 nanosheets were synthesized by means of a CVD method. • A novel Nd:GdYNbO 4 mixed crystal was grown and used as laser medium. • Pulsed MoS 2 /WS 2 Nd:GdYNbO 4 lasers performance was demonstrated for the first time. Utilizing the saturable absorption characteristics of transition metal dichalcogenides (TMDs), a passively Q-switched 1066 nm laser based on a novel Nd:GdYNbO 4 mixed crystal as well as a two-dimensional (2D) layered molybdenum disulfide (MoS 2) and tungsten disulfide (WS 2) was realized for the first time. The highest repetition rate, the shortest pulse width and maximum peak power were 172 kHz, 723 ns and 0.85 W for Nd:GdYNbO 4 /WS 2 laser, respectively. The corresponding values for the Nd:GdYNbO 4 /MoS 2 laser were 122 kHz, 532 ns and 1.63 W. Furthermore, it was found that WS 2 required a lower excitation energy, while a MoS 2 nanosheet exhibits a deeper modulation depth. [ABSTRACT FROM AUTHOR]

With the further exploration of outer space by human beings, the demand for outer space laser is increasing. Therefore, developing laser materials that can resist the space irradiation become increasingly important. In this study, high quality Nd, Cr:GSAG crystal was grown successfully by Czochralski method. The X-ray diffraction results indicate that the crystal structure remains unchanged after the irradiation with 60Co gamma-ray. In addition, Raman, absorption and fluorescence spectra of the as-grown crystal are almost unaffected by the irradiation, suggesting the excellent radiation resistant ability of the crystal. Compared with the Nd:GSAG crystal, the co-doping of Cr3+ can enhance the radiation resistant ability and luminescent efficiency apparently. Importantly, LD pumped 1.06 μm laser results indicate the Nd, Cr:GSAG crystal can be considered as a promising high efficiency laser material for the application in harsh radiation environment, such as in outer space. [ABSTRACT FROM AUTHOR]

Highlights • A novel Nd:GdLaNbO 4 mixed crystal was investigated and used as laser medium. • A two-dimensional WS 2 nanosheet was prepared and served as saturable absorber. • The Q-switched Nd:GdLaNbO 4 laser based on WS 2 was demonstrated for the first time. Abstract In this paper, we present a diode-pumped passively Q-switched laser based on a novel Nd:Gd 0.89 La 0.1 NbO 4 mixed crystal and two-dimensional (2D) tungsten disulfide (WS 2) saturable absorber. After the optimization of the laser parameters, a maximum continuous-wave (CW) output power of 4.37 W with a slope efficiency of 42% was obtained, which is the highest output power to the best of our knowledge. Utilizing the saturable absorption characteristic of the 2D WS 2 material, the pulsed Nd:Gd 0.89 La 0.1 NbO 4 laser performance was investigated. The shortest pulse duration of 895 ns and the highest repetition rate of 162 kHz were realized at an absorbed pump power of 7.18 W. [ABSTRACT FROM AUTHOR]

• A novel Nd:Gd 0.69 Y 0.3 NbO 4 mixed crystal was used as laser gain medium. • A 2D MoS 2 nanosheet was used as saturable absorber. • A 2D MoS 2 passively Q-switched Nd:GdYNbO 4 laser was demonstrated for the first time. A diode-pumped MoS 2 passively Q-switched Nd:Gd 0.69 Y 0.3 NbO 4 laser at 1066 nm was demonstrated for the first time. The maximum continuous (CW) wave output power of 1.77 W was obtained when the absorbed pump power was 7.28 W and the transmission of flat output coupler was 25%. The maximum slope efficiency reached 33.3%. The pulsed laser with high repetition rate was obtained when the two-dimensional (2D) MoS 2 material was used as the saturable absorber. The highest repetition rate and the narrowest pulse width were reached 112 kHz and 532 ns, respectively. [ABSTRACT FROM AUTHOR]

Highlights • Nd:GSAG crystal with high doping concentration was used as laser gain medium. • A high slope efficiency of 56.9% of Nd:GSAG laser was obtained. • A 2D WS 2 passively Q-switched Nd:GSAG laser was demonstrated for the first time. Abstract A diode-pumped passively Q-switched Nd:GSAG laser at 1060 nm with a novel two-dimensional tungsten disulfide (WS 2) saturable absorber was demonstrated for the first time. In the continuous-wave operation, the maximum output power of 4.68 W was obtained with the output coupler transmission of 10%, at absorbed pump power of 9.95 W. The corresponding slope efficiency benefiting from high doping concentration (3%) of Nd:GSAG was up to 56.9%, which reached the highest value for Nd:GASG laser at 1060 nm, as far as we know. In the passively Q-switched operation, when the absorbed pump power was 3.96 W, pulse width and repetition rate were 1.5 μs and 146.9 kHz, respectively. [ABSTRACT FROM AUTHOR]

• The EO Q-switched laser performance with Nd:GdTaO 4 was investigated. • Pulsed laser output at 1066 nm with a peak power of 61.75 kW was obtained at 1 kHz. • The results show Nd:GdTaO 4 is a promising candidate for pulsed lasers. In this work, we reported an electro-optically Q-switched Nd:GdTaO 4 1066 nm laser under 879 nm laser diode pumping. Pulsed laser output at 1066 nm with a pulse width of 5.7 ns, a single pulse energy of 352 μJ and a peak power of 61.75 kW was obtained at 1 kHz when the pump pulse energy was 4.5 mJ. At a repetition rate of 2 kHz, the 45.4 kW peak power was achieved with a pulse width of 6.2 ns and a single pulse energy of 281 μJ. The optical-to-optical conversion efficiency was 8.1%. The beam quality factors of 2 kHz 1066 nm laser were measured to be M2 x = 1.29, M2 y = 1.21 at a pump pulse energy of 3.3 mJ by using the traveling 90/10 knife-edge method. [ABSTRACT FROM AUTHOR]

The present work successfully demonstrated a passively Q-switched solid-state 1 µm Nd:GSAG laser using a few layer molybdenum disulfide (MoS 2) saturable absorber. Controllable dual wavelengths of 1059.94 nm and 1062.3 nm were achieved in the experiment. We obtained the shortest pulse width of 217 ns and the highest pulse repetition frequency of 51.2 kHz. The pulse energy and peak power are 9.5 μJ and 43.7 W, respectively. To our knowledge, this is the first time that dual wavelengths with a controllable intensity ratio have been obtained in a Q-switched solid-state laser based on a MoS 2 saturable absorber at 1 μm. The results demonstrate that MoS 2 is a highly reliable optical modulator for dual wavelength laser applications. [ABSTRACT FROM AUTHOR]

• Nd:GdNbO 4 was used as a laser gain medium. • Nd:GdNbO 4 laser under 879 nm pumping was demonstrated. • Detailed pulsed Nd:GdNbO 4 /PtSe 2 laser performance was reported. A pulsed Nd:GdNbO 4 laser using two-dimensional (2D) platinum diselenide (PtSe 2) nanosheet as a saturable absorber (SA) is reported for the first time. The optical characteristics and microstructure of PtSe 2 nanosheet were investigated at first. The passively Q-switched 1.06 μm Nd:GdNbO 4 /PtSe 2 laser was carried out under direct pumping. A 426 mW maximum average output power was achieved. The obtained pulse duration, repetition rate, pulse energy and peak power were 300 ns, 210 kHz, 2 μJ and 6.8 W, respectively, when the absorbed pump power of Nd:GdNbO 4 crystal was 3.8 W. [ABSTRACT FROM AUTHOR]

• CW and pulsed1066 nm Nd:GdNbO 4 laser under direct pumping was demonstrated. • The comparison between indirect pumping and direct pumping was performed. • Pulsed SnSe 2 /Nd:GdNbO 4 and PdSe 2 /Nd:GdNbO 4 lasers were obtained for the first time. In this paper, a continuous wave (CW) and two-dimensional (2D) tin diselenide (SnSe 2) and palladium diselenide (PdSe 2) passively Q-switched Nd:GdNbO 4 laser under direct pumping was demonstrated for the first time. The CW laser performance under the pump at 879 nm was compared to that using traditional 808 nm pumping. The 2D SnSe 2 and PdSe 2 nanosheets were synthesized by chemical vapor deposition (CVD) technique. The optical properties and microstructures of two nanosheets were investigated. In the passively Q-switched operation, the highest repetition rate, narrowest pulse width, maximum pulse energy and peak power of SnSe 2 /Nd:GdNbO 4 laser were 160 kHz, 555 ns, 2.3 μJ and 4.2 W, respectively. And for PdSe 2 /Nd:GdNbO 4 laser, the corresponding values were 143 kHz, 530 ns, 3.7 μJ and 7.0 W, respectively. [ABSTRACT FROM AUTHOR]

• Nd:GdNbO 4 crystal was adopted as laser gain medium. • 1066 nm Nd:GdNbO 4 laser under direct pumping was demonstrated for the first time. • Pulsed Nd:GdNbO 4 /WS 2 laser performance was investigated for the first time. This paper reports a tungsten disulfide (WS 2) passively Q-switched 1066 nm Nd:GdNbO 4 laser under an 879 nm diode directly pumping into emitting level for the first time. In the passively Q-switched operation, an average output power of 220 mW, pulse repetition rate of 143 kHz, pulse width of 376 ns, single pulse energy of 1.55 μJ and pulse peak power of 4.17 W were achieved. [ABSTRACT FROM AUTHOR]

• Passively Q-switched mode-locking Nd:TaGdO 4 /Cr4+:YAG 1066 nm laser is presented. • A comparative study of pulsed 1066 nm laser is performed in different cavities. • Repetition rate enhancement is realized by harmonic mode locking. • Up to 9th order harmonic mode locking 1066 nm laser at 655 MHz is achieved. In this work, harmonic mode locking in a laser diode pumped passively Q-switched mode-locked Nd:GdTaO 4 1066 nm laser is presented by using Cr4+:YAG as saturable absorber. The average output power of the passively Q-switched mode-locked 1066 nm laser reaches 4.7 W with a repetition rate of 200.0 MHz and a pulse width of ~1.3 ns within a Q-switched envelope of 150.0 ns. By changing the Z-type cavity length, high-order harmonic mode locking operation of the passively Q-switched 1066 nm laser is conducted. The 3rd-order harmonically mode-locked 1066 nm laser yields a maximum average output power of 3.2 W and a pulse width of ~570 ps at 164.5 MHz repetition rate inside a Q-switched envelope of 419.7 ns long. The pulse repetition rate reaches 655.3 MHz in the 9th-order harmonically mode-locked 1066 nm laser. [ABSTRACT FROM AUTHOR]

• In cw laser operation, the higher optical-to-optical efficiency and slope efficiency were obtained. • Laser performance comparison was conducted under 808 nm and 879 nm laser diode (LD) pumping. • In acousto-optically Q-switched operation, laser performances were improved. • Under 879 nm pumping, the Nd:GYTO laser thermal effects were investigated. This study investigated the laser performance of a Nd:GdYTaO 4 crystal in continuous-wave and acousto-optically Q-switched operation. Laser performance comparison was conducted under 808 nm and 879 nm laser diode (LD) pumping. In continuous-wave operation, the maximum power at 1066 nm reached 4.4 W with an optical-to-optical efficiency of ~33.6% and the slope efficiency was ~35.9% under 808 nm laser diode pumping. In comparison, an output power of 7.7 W with an optical-to-optical efficiency of ~47.8% and a slope efficiency of ~48.3% were achieved in 879 nm LD pumped 1066 nm laser. Under 808 nm LD pumping, the Nd:GdYTaO 4 crystal yielded an average output power of 1.1 W and a pulse width of 59.5 ns at the repetition rate of 30 kHz. By using direct pumping directly into the 4F 3/2 emitting level, the average power was increased to 1.9 W and the pulse width was shortened to 33.0 ns at the repetition rate of 30 kHz. [ABSTRACT FROM AUTHOR]

A continuous wave (CW) and passively Q-switched 1. 06 μ m Nd:GdLaNbO 4 laser under direct 879 nm pumping is firstly reported in this paper. The CW output power and slope efficiency varied from 4.50 W and 45.6% to 6.55 W and 50.0% when the indirect pumping of 808 nm was changed to the direct pumping of 879 nm. Furthermore, the beam quality was also improved significantly. For the CW Nd:GdLaNbO 4 laser, as is known to all that the highest output power with excellent beam quality was obtained. In the Q-switched operation, rhenium disulfide (ReS 2) synthetized by chemical vapor deposition (CVD) method was employed as a saturable absorber (SA). The optical properties and atom force microscope (AFM) image of ReS 2 were measured and recorded to characterize it. A maximum average output power with 312 mW, a narrowest pulse width with 400 ns, and a highest repetition rate with 147 kHz were obtained under the direct 879 nm pumping. [ABSTRACT FROM AUTHOR]

• Nd:GdNbO 4 crystal was used as the gain medium. • Nd:GdNbO 4 laser under direct pumping was demonstrated. • Pulsed Nd:GdNbO 4 /MoS 2 laser performance was investigated for the first time. In this paper, the characteristic of passively Q-switched Nd:GdNbO 4 laser using two-dimension (2D) material MoS 2 as SA under 879 nm direct pumping was demonstrated for the first time. When absorbed pump power was 4.36 W, the maximum average output power, narrowest pulse width and highest repetition frequency were measured as 427 mW, 740 ns and 89 kHz, respectively. At the same absorbed pump power, the maximum pulse energy and peak power were calculated as 4.8 μJ and 6.48 W, respectively. [ABSTRACT FROM AUTHOR]

• 2D PdSe 2 nanosheet was synthesized and characterized. • PdSe 2 nanosheet was used as saturable absorber for the first time. • Pulsed Nd:GdLaNbO 4 /MoS 2 laser performance was demonstrated for the first time. In this work, a novel two-dimensional palladium diselenide (PdSe 2) nanosheet was synthesized by chemical vapour deposition method and used as a saturable absorber (SA) for generation of Q-switched laser pulses. The microstructure and optical properties of PdSe 2 nanosheet were investigated. For laser emission, a newly developed Nd:GdLaNbO 4 mixed crystal was used as the gain medium, while the pump was done with fiber-coupled diode laser at 879 nm, directly into the 4F 3/2 emitting level. The Q-switched Nd:GdLaNbO 4 /PdSe 2 laser yielded 405 mW average output power for 8.8 W absorbed pump power at 879 nm. The laser runs at 164 kHz with 2.47 μJ energy per pulse; pulse duration was 340 ns, indicating a pulse peak power of 7.26 W. These first results prove that PdSe 2 nanosheet can be used as SA in passively Q-switch laser devices. [ABSTRACT FROM AUTHOR]

• The performance of self-Q-switching Nd:YSAG operation is studied. • A stable black phosphorus saturable absorber (BP-SA) was prepared. • The passively Q-switched mode-locking operation by using BP-SA is investigated. • Generation of dual-wavelength picosecond pulses by QML operation. • SQS and QML operating at dual-wavelengths of 1058.97 and 1061.49 nm, respectively. In this paper, self-Q-switched (SQS) and passively Q-switched mode-locked (QML) dual-wavelength Nd:YSAG lasers are reported, that works at 1058.97 and 1061.49 nm, simultaneously. Till now, the performance on SQS, and passively QML operation by using black phosphorus (BP) in Nd:YSAG crystal lasers have not been reported as per the author's knowledge. The Nd:YSAG laser SQS operation was realized by designing a simple plano-plano resonator cavity. The maximum output power of 0.471 W at absorbed pump power 2.64 W and the pulse duration was 885 ns. The Nd:YSAG laser QML operation was realized by designing a Z-type resonator cavity. The duration of mode-locked pulse inside the Q-switched envelop was estimated to be 235 ps with 96.5 MHz repetition rate at the absorbed pump power of 4.08 W in QML with black phosphorus saturable absorber (BP-SA). [ABSTRACT FROM AUTHOR]

• 2D MoS 2 nanosheet was synthesized and characterized. • A novel Nd:GdLaNbO 4 mixed crystal was used as laser medium. • Pulsed Nd:GdYNbO 4 /MoS 2 laser performance was demonstrated for the first time. A novel pulsed 1065 nm Nd:GdLaNbO 4 laser using 2D material molybdenum disulfide (MoS 2) as saturable absorber was demonstrated for the first time to our best knowledge. The characteristic of 2D MoS 2 nanosheet was examined firstly. Then, the continuous wave output power was tested and corresponding intensity distribution and beam quality factors were measured and calculated, respectively. Through adding of MoS 2 nanosheet, the obtained shortest pulse duration, highest repetition rate and peak power were 0.59 μs, 112 kHz and 1.90 W, respectively. [ABSTRACT FROM AUTHOR]

• A high efficiency passively Q-switched Nd:GdTaO 4 laser at 1066 nm is presented. • Q-switched pulse with high repetition rate and short pulse width are obtained. • Compact structure, small volume, suitable for various narrow working environments. We report an 879 nm laser diode directly pumped passively Q-switched Nd:GdTaO 4 laser at 1066 nm. The continuous-wave output power at 1066 nm reaches 5.6 W under an incident pump power of 12.8 W, corresponding to an optical-to-optical efficiency of 43.8% and a slope efficiency of 48.0%. By using Cr4+:YAG as the saturable absorber, passively Q-switched laser operation is conducted, yielding a highest pulse repetition frequency of 185 kHz and a maximum average power of 3.6 W. The shortest pulse width of 15.2 ns is achieved with a peak power of 2.34 kW at 33.7 kHz. The beam quality factors at the maximum average output power is measured to be M x 2 = 2.2, M y 2 = 1.5 by using knife-edge method. The thermal focal length and internal loss for Nd:GdTaO 4 crystal is also investigated. [ABSTRACT FROM AUTHOR]