Passively Q-switched,high peak power Nd:YAG laser pumped by QCW diode laser

A Nd:YAG laser passively Q-switched by a Cr:YAG showed a high single pulse energy of 53.0 mJ and 5.1 MW peak power. The laser was pumped by quasi-continuous-wave diode bars from single side. The Q-switched pulse had optical-to-optical efficiency of 12% and average temporal duration of 10.4 ns when Cr:YAG with initial transmission of 9.0% was used. Intense pumping as well as very low initial transmission of the saturable absorber gave very high peak power.     

LD-end-pumped passively Q-switched Nd:YAG ceramic laser with single wall carbon nanotube saturable absorber

We report on a LD-end-pumped passively Q-switched Nd:YAG ceramic laser by using a novel single wall carbon nanotube saturable absorber (SWCNT-SA). The SWCNT wafer was fabricated by electric Arc discharge method on quartz substrate with absorption wavelength of 1064 nm. We firstly investigated the continuous wave (CW) laser performance and scattering properties of Nd:YAG ceramic sample. For the case of passively Q-switched operation, a maximum output power of 376 mW was obtained at an incident pump power of 8.68 W at 808 nm, corresponding to an optical–optical conversion efficiency of 4.3%. The repetition rate as the increase of pump power varied from 14 to 95 kHz. The minimum pulse duration of 1.2 μs and maximum pulse energy of 4.5 μJ was generated at a repetition rate of 31.8 kHz.     

An experimental study of an acousto-optic Q-switched Yb3+-doped all-fiber laser

The Q-switched fiber lasers are very attractive sources in many applications such as military affairs, surgical operation, laser machining, laser marking, nonlinear frequency conversion, range finding, remote sensing and optical time domain reflectometer. In this paper, an acousto-optic Q-switched Yb³⁺-doped all-fiber laser at 1083 nm is reported. The pulse energy of 2.94 mJ has been obtained at the pump power of 8.47 W, and the pulse width is 3 μs.     

Diode-pumped Nd:YAG ceramic laser at 946 nm passively Q-switched with a Cr4+:YAG saturable absorber

We demonstrate a diode-pumped Nd:YAG ceramic laser with emission at 946 nm that is passively Q-switched by single-crystal Cr⁴⁺:YAG saturable absorber. An average output power of 1.7 W is measured under 18.4 W of incident power using an output mirror with transmission T=4%. The corresponding optical-to-optical efficiency is 9.2%. The laser runs at a pulse repetition rate of 120 kHz and delivers pulses with energy of 14 μJ and duration of 80 ns, which corresponds to a peak power of 175 W.     

Intracavity optical parametric oscillator pumped by passively Q-switched Nd:YLF laser

We report on a passively Q-switched end pumped Nd:YLF laser including a noncritically phase-matched KTP singly resonant intracavity optical parametric oscillator (IOPO-KTP). For the Q-switching operation we have used Cr:YAG saturable absorber. The optimized passively Q-switched Nd:YLF laser without IOPO generated linearly polarized pulses of 11.5 ns and 1.07 mJ at 1047 nm. The conversion efficiency of the optimized Q-switched pulse energy at 1047 nm to 1547 nm of a signal approached about 47%. For optimizing both Nd:YLF laser and IOPO we have numerically solved a theoretical model. We have achieved 1.6-ns duration pulses at 1547 nm with energy of 0.5 mJ and peak power of above 300 kW. The beam quality was excellent (M² ≈1).     

Design and construction of Q-switched Nd:YAG laser system for LIBS measurements

A passive, Q-switched pulsed, Nd:YAG laser system was designed and built, which can provide a potential compact robust laser source for portable laser induced breakdown spectroscopy systems.The developed laser system operates at 1064 nm. Each laser shot contains a train of pulses having maximum total output energy of 170 mJ. The number of pulses varies from 1–6 pulses in each laser shot depending on the pump energy. The pulse width of each pulse ranges from 20 to 30 ns. The total duration of the output pulse train is within 300 μs. The multi-pulse nature of the laser shots was employed to enhance the LIBS signal. To validate the system, LIBS measurements and analysis were performed on ancient ceramic samples collected from Al-Fustat excavation in Old Cairo. The samples belong to different Islamic periods in Egypt history. The results obtained are highly indicative that useful information can be provided to archeologists for use in restoring and repairing of precious archeological objects.     

1.34 μm fluorescence and laser properties of Nd:La0.11Y0.89VO4 crystal

For Nd:La_xY_1−xVO₄ (x = 0.11) crystal, the ⁴F_3/2 → ⁴I_13/2 transition property was investigated for the first time. The fluorescence peak of Nd:La_0.11Y_0.89VO₄ crystal exhibited obvious inhomogeneous broadening comparing with that of Nd:YVO₄ crystal. With laser diode array as pump source, 1.34 μm continuous-wave (CW) and active Q-switched laser operations based on ⁴F_3/2 → ⁴I_13/2 transition were realized. For CW laser operation, the maximum output power of 2.47, 2.13 W is obtained with slope efficiencies of 29.4%, 27.6%, and optical to optical conversion efficiency of 26.2%, 24.7%, respectively for a, c cut crystal samples. For acousto-optic (AO) Q-switched laser operation, the shortest pulse width, highest peak power and maximum pulse energy came from the a-cut sample, which were 13 ns, 2.69 kW and 35 μJ, respectively.     

Diode-pumped doubly Q-switched Nd:Lu0.33Y0.37Gd0.3VO4 laser with an electro-optic modulator and a single-walled carbon nanotube saturable absorber

By simultaneously using an electro-optic (EO) modulator and a single-walled carbon nanotube saturable absorber (SWCNT-SA) in the cavity, a diode-pumped doubly Q-switched Nd:Lu_0.33Y_0.37Gd_0.3VO₄ (Nd:LuYGdVO₄) laser is demonstrated. At the incident pump power 11.43 W and f=2 kHz, the minimum pulse width 17.6 ns and the maximum pulse peak power 19,886 W can be obtained. The experimental results show that this doubly Q-switched Nd:LuYGdVO₄ laser can generate shorter pulse width and higher peak power compared to the singly Q-switched Nd:LuYGdVO₄ laser with only EO or SWCNT-SA.     

Laser micro-machined semi-slinky like MEMS structures: Novel interface coolers

Laser micro-machining has recently been considered a precision and reproducible manufacturing technique in MEMS fabrication because of the superior characteristics of a focused laser beam. It is not only a unique tool but also an invisible optical drill. The aim of the present paper is two-fold: to manufacture novel miniaturized titanium 3D MEMS surface structures in order to increase the cooling performance. Second is to find the behaviors of the operational parameters which controlling the laser-material interaction mechanisms and also suggest the best adjustments in order to achieve this novel semi-slinky like spiral MEMS surface structures with using a 20 W ytterbium fiber laser. Pure titanium micro-MEMS product which has novel interface coolers was manufactured using a ytterbium fiber laser (λ=1060 nm) with 40 ns pulse duration. Best adjustments were, respectively, the pulse duration: 40 ns, the pulse energy: 0.4 mJ, the laser scanning speed: 336.1 mm/s, the peak power density: 17.46 ? 10⁸ W/cm².     

A diode end-pumped passively Q-switched Nd:YAG/KTA Raman laser

A diode end-pumped passively Q-switched Nd:YAG/KTA intracavity Raman laser is presented. A KTA crystal with a size of 5 mm × 5 mm × 25 mm is used as the Raman active medium and its 234 cm^?1 Raman mode is employed to finish the conversion from 1064 nm fundamental laser to 1091 nm Raman laser. A 2 mm thick Cr⁴⁺:YAG crystal is used as the saturable absorber. With an LD pump power of 7.5 W, the first-Stokes power of 250 mW is obtained with a pulse repetition frequency of 14.5 kHz. The corresponding diode-to-Stokes conversion efficiency is 3.3% and the pulse energy is 17.2 μJ. Pulse width is measured to be 12.6 ns and peak power is 1.4 kW.     

A 980 nm Yb-doped single-mode fiber laser pumped by a 946 nm Q-switched Nd:YAG laser

We demonstrate a 980 nm single-mode Yb-doped fiber laser with a 946 nm Q-switched Nd:YAG laser used as the pump source. The experimental arrangement exploited a 36.5 cm length of fiber and used the output from both ends of the cavity, providing a total average output power of 100 mW with a slope efficiency of 38%. In order to increase the coupling efficiency and the practicability of the fiber laser, another experimental setup with single ended output was studied, producing an average output power of 80 mW from a fiber length of 23.5 cm. The pulse duration is 10 ns at a repetition frequency of 16 kHz. The linewidth of the laser is 4 nm, ranging from 977 to 981 nm.     

Cavity-dumped electro-optical Q-switched Nd:GdVO4 laser with high repetition rate

We reported a cavity-dumped operation of electro-optical Q-switched Nd:GdVO₄ laser at high repetition rates for the first time. A constant 5.5 ns pulse duration was realized. The maximum average output power was 5.1 W at the highest repetition rate of 50 kHz, corresponding to a peak power of 18.5 kW.     

Cr4+:YAG passively Q-switched c-cut Nd:YVO4 self-Raman laser at 1168.6 nm

We demonstrate the first Cr⁴⁺:YAG passively Q-switched c-cut Nd:YVO₄ self-Raman laser at 1168.6 nm based on the Stokes shift of 816 cm⁻¹. At the pump power of 4.7 W, the maximum output power of the Stokes line at 1168.6 nm is 270.5 mW, corresponding to an optical conversion efficiency of 5.8%. The pulse width, pulse repetition rate, pulse energy and peak power are 8.8 ns, 35.8 kHz, 7.6 μJ and 0.86 kW, respectively. At the pump of 5.0 W, the Stokes line at 1097.2 nm based on Raman shift of 259 cm⁻¹ also appears.     

Efficient end-pumped Q-switched 1053 nm Nd:YLF laser with a plane-parallel resonator

In this study, a compact and efficient Nd:YLF laser at 1053 nm has been reported without inserting optical intracavity element to suppress the stronger line of 1047 nm. According to theoretical analysis and calculation, the thermal focal length of 1047 nm is negative while that of 1053 nm is positive in plane-parallel resonator. Hence 1053 nm laser was stable in this cavity. In our experiment, 7.5 W laser output at σ-polarized 1053 nm has been obtained with optical–optical efficiency of 38.8%. As the pulse repetition rate is 20 kHz, the pulse width is 50 ns and the peak power is calculated to be 7.5 kW.     

Performance of actively Q-switched Nd:LiLuF<Subscript>4</Subscript> crystal end-pumped by a 792 nm laser diode

An efficient laser diode end-pumped continuous-wave (CW) and AO Q-switched laser of Nd:LiLuF₄ crystal with dual central wavelengths of 1053.1 and 1054.7 nm is reported for the first time. The maximum CW output power of 6.22 W was obtained at absorbed pump power of ∼14.6 W with the output transmission of 2%. The optical conversion efficiency is ∼43%, corresponding to a slope efficiency of about 48% with respect to the absorbed pump. For the Q-switched operation, the shortest pulse width of 17 ns was obtained at the pulse repetition frequency (PRF) of 0.5 kHz, resulting in a pulse energy of 2.24 mJ and peak power of 131.8 kW.     

Electro-optical cavity-dumped Ce:Nd:YAG laser for aesthetic medicine

An electro-optical cavity-dumped 20 Hz Ce:Nd:YAG laser with an optimized thermal-insensitive concavo-convex cavity for aesthetic medicine was demonstrated. The pulse width remained constant at 6.0 ns. The maximum output energy and peak power were 120 mJ and 20 MW, respectively. The average output energy was very stable. The fluctuations of average output energy within 6 cycles and 10 min were 0.89% and 7.9%, respectively.     

Improvement of stability and pulse energy in a diode-pumped dual-loss-modulated QML Nd:Lu0.2Y0.8VO4 laser with EO modulator and GaAs

The Q-switched and mode-locked (QML) performance in a diode-pumped Nd:Lu_0.2Y_0.8VO₄ laser with electro-optic (EO) modulator and GaAs saturaber absorber is investigated. In comparison with the solely passively QML laser with GaAs, the dual-loss-modulated QML laser with EO and GaAs can generate pulses with higher stability and shorter pulse width of Q-switched envelope, as well as higher pulse energy. At the repetition rate 1 kHz of EO, the pulse width of Q-switched pulse envelope has a compression of 89% and the pulse energy has an improvement of 24 times. The QML laser characteristics such as the pulse width, pulse peak power etc. have been measured for different small-signal transmittance (T₀) of GaAs, different reflectivity (R) of output coupler and modulation frequencies of the EO modulator (f_e). The highest peak power and the shortest pulse width of mode-locked pulses are obtained at f_e = 1 kHz, R = 90% and T₀ = 92.6%. By considering the influences of EO modulator, a developed rate equation model for the dual-loss-modulated QML laser with EO modulator and GaAs is proposed. The numerical solutions of the equations are in good agreement with the experimental results.     

Passively Q-switched a-cut Nd:GdVO4 self-Raman laser with Cr:YAG

A passively Q-switched a-cut Nd:GdVO₄ self-Raman solid-state laser with Cr:YAG saturable absorber was firstly demonstrated. The first Stokes at 1173 nm was successfully obtained. At the maximum incident pump power, the pulse width was about 1.8 ns and the repetition rate was 27.5 kHz. 586.5 nm yellow laser output was also realized by use of an LBO frequency doubling crystal.     

High efficiency diode-pumped slab oscillator and amplifier for space-based application

The design and performance of conduction-cooled, laser diode-pumped oscillator and amplifier slab laser featuring high efficiency, high pulse energy and high beam quality for space-based application are reported. The oscillator was a diode-pumped Q-Switched Nd:YAG slab laser using unstable resonator, and the amplifiers were two zig-zag Nd:YAG slabs based on a side-pumped slab geometry. A near diffraction-limited output of 450 mJ in a 10 ns pulse at a repetition rate of 20 Hz was obtained, corresponding to an optical-to-optical conversion efficiency of over 20%.     

A neodymium fluid laser: Laser emission in circulating state

Differing from conventional liquid lasers, a novel concept of fluid laser was provided, which has attractively potential using in high average power lasers. The laser medium was prepared by dispersing Nd³⁺: phosphate glass micro-balls in organic match liquid. Its optical properties were investigated and the radiative transition rate was calculated by Judd–Ofelt theory. The experiment of laser oscillation in static state indicates that the heat exchanging has limited effect on refractive index of the fluid laser medium in a short time. In circulating state, a laser oscillation occurred at 1058.1 nm when pumped by two 808 nm diode lasers. The maximum output energy is 2.58 mJ with the absorbed pumping energy of 460 mJ. This study offers a new way in the exploration of high average power laser.