Diode-end-pumped 1D top-hat Nd：YVOa slab laser

A one-dimensional （1D） top-hat, diode-end-pumped, electro-optically Q-switched Nd：YVO4 slab laser is demonstrated. Under the pump power of 175.5 W, 26.3-W output power is obtained with the repetition rate of 5 kHz and the pulse width of 4.3 ns. The output beam has a good top-hat beam profile in both the near field and the far field.     

Laser diode end-pumped Nd：YVO4 regenerative amplifier for picosecond pulses

A diode dual-end-pumped Nd:YVO4 regenerative amplifier is reported. The influence of the cavity stability on the performance of the regenerative amplifier is studied. The experimental results match well with the analysis at high pump power. The mode locking seed pulses with 15 ps pulse width and 10 nJ single pulse energy at 86 MHz are amplified up to 4.7 mJ at 1 kHz, corresponding to the maximum amplification about 0.5 × 106 , by our regenerative amplifier. And an average power of 4.7 W is obtained at the repetition rate from 1 kHz to 10 kHz.     

Suppressing the preferential o-polarization oscillation in a high power Nd：YVO4 laser with wedge laser crystal

We observe the phenomenon of priority oscillation of the unexpected a-polarization in high-power Nd：YVO4 ring laser. The severe thermal lens of the a-polarized lasing, compared with the n-polarized lasing, is the only reason for the phenomenon. By designing a wedge Nd：YVO4 crystal as the gain medium, the unexpected a-polarization is completely suppressed in the entire range of pump powers, and the polarization stability of the expected zc-polarized output is enhanced. With the output power increasing from threshold to the maximum power, no a-polarization lasing is observed. As a result, 25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated.     

Large-aperture end-pumped Nd：YAG thin-disk laser directly cooled by liquid

A large-aperture Nd:YAG thin-disk laser directly cooled by liquid is end-pumped by two spatial selforganized laser diode arrays. The pump coupling efficiency reaches as high as 93%. Without any complex pump coupling components, the structure becomes simplified and compact. By optimizing the incident angle of the pump beam, a pump power density of 578 W/cm2 is achieved with a pump uniformity of 5.52%. Up to 1 346-W peak output power with a slope efficiency of 54.9% is obtained when pumping with a long pulse. The near-field pattern of the laser output is uniform.     

Simulation of Patterns and Qualitative Analysis of Pattern Rotation in an End-Pumped Nd：YVO4 Laser

We simulate some laser output patterns observed in our previous experiment employing superposition of Laguerre- Gaussian modes. The rotating pattern is qualitatively analysed from the point of contemporary spatial burning hole effect of the lasing crystal.     

Design and preparation of multilayer optical coatings for laser crystal Nd：YVO4 and KTP

Design and preparation of multilayer optical coatings are investigated on laser crystal Nd：YVO4, YVO4, and frequency doubling crystal KTP substrate. Multilayer optical coatings are deposited on one surface of the crystals using the ion beam sputtering technique, and the other surface is coated with a single SiO2 as protective layer. For the YVO4 crystal after coating, the reflectivity at 1 064 and 532 nm are greater than 99.9% and 99.8%, respectively, and the transmissivity at 808 nm is greater than 91.5%. For the KTP crystal after coating, the reflectivity at 1064 nm is greater than 99.95%, and the transmissivity at 532 nm is greater than 99.5%. After thermal annealing, the transmissivity can be improved. The obtained coated crystals can be used in high Dower solid-state lasers.     

An 880-nm Laser-Diode End-Pumped Nd：YVO4 Slab Laser with a Hybrid Resonator

We present an experimental study of a continuous-wave Nd： YVO4 laser diode-pumped directly in band at 880 nm. By using a compact positive confocal unstable-stable hybrid resonator, a maximal laser output of 170 W at 1064 nm is realized. The slope efficiency and optical-to-optical efficiency are 56.7% and 51.3%, respectively. The M2 factors in the unstable direction and in the stable direction they are 1.9 and 1.3, respectively.     

Diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG /KTP green laser

We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG green laser with a KTP crystal as the intra-cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170±20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.     

Investigation on mode matching including thermal effects in LD end-pumped passively mode-locked Nd：YVO_4 laser

We design a laser diode （LD） end-pumped passively mode-locked solid-state laser with a semiconductor saturable absorber mirror. Mode-matching efficiency in the active medium including the thermal effect is analyzed, and the optimum mode-matching coefficient is obtained by optimizing the pump mode. In the experiment, a total power of 4.2 W stable pulse sequences without multipulse at 1064 nm is obtained with a pulse repetition rate of 86 MHz and a pulse width of 13 ps, corresponding to a high optical to optical efficiency of 44%.     

6.5-ns actively Q-switched Nd：YVO4 laser operating at 1.34 μm

A novel design of multimode light power splitter is proposed and fabricated by using secondary asymmetric Y branches.An almost equally divided output among output terminals is obtained experimentally.Maskless laser direct writing technique is applied in the fabrication process to facilitate the formation of power splitters by ultraviolet curable polymer.The analysis of the performances of both four-port and eight-port devices shows that these two dividers obtain a power splitting uniformity of more than 95%.     

Diode Pumped Operation of Tm,Ho：YVO4 Microchip Laser

A cryogenic and room-temperature diode pumped Tm,Ho：YVO4 microchip laser with 0.5 mm crystal length lasing around 2μm is demonstrated for the first time to our knowledge. Under cryogenic temperature of 77 K, as much as 1.2 W output and slope efficiency of 35% with respect to absorbed pump power are obtained. At temperature of 5℃ the maximum output power of 48mW is obtained at an absorbed pump power of 503 mW, representing a 9.5% optical to optical conversion efficiency. In addition, as much as 8 mW single-frequency output lasing at 2052.6 nm is achieved at room temperature of 15℃.     

High-Power Nd：GdVO4 Innoslab Continuous-Wave Laser under Direct 880 nm Pumping

A high-power cw end-pumped laser device is demonstrated with a slab crystal of Nd：GdVO4 operating at 1063nm. Diode laser stacks at 880nm are used to pump Nd：GdVO4 into emitting level 4^F3/2. The 149 W output power is presented when the absorbed pump power is 390 W and the optical-to-optieal conversion efficiency is 38.2%. When the output power is 120 W, the M^2 factors are 2.3 in both directions. Additionally, mode overlap inside the resonator is analyzed to explain the beam quality deterioration.     

Compact high-power mode-locked Nd：YVO4 picosecond laser using multiple-pass cavity

A stable self-starting mode-locked Nd:YVO4 laser with a Herriott-type multiple-pass cavity(MPC) operating at 1 064 nm is demonstrated.An in-band 880-nm laser diode is used as an end-pump and a semiconductor saturable absorber mirror(SESAM) is used for passive mode locking(ML) and providing pulse durations of 14 ps.At a pump power of 26.4 W,the maximum average output power is as high as 10.5 W at a repetition rate of 22 MHz,which corresponds to a single pulse energy of 0.48 μJ.Optical-tooptical conversion efficiency is as high as 39.8% at the maximum output power with a slope efficiency of 55.2%.     

High Efficiency Multi-kW Diode-Side-Pumped Nd：YAG Laser with Reduced Thermal Effect

We demonstrate a high efficiency multi-kW diode-side-pumped Nd：YAG laser. High cooling efficiency of the diode-side-pumped module in the laser is achieved. The middle portion of the Nd：YAG rod in the module is cooled by a coolant jet with screwed side surface, and the end-caps of the rod without screwed side surface are cooled by Au coated on the surface. The thermal effect of the laser rod is reduced, which leads to high output power with high optical-optical conversion efficiency. By using three identical Nd：YAG laser modules, an output power of 4.2 kW and beam quality of 58 mm＆#12539;mrad with an optical-optical efficiency of 35% at 1064 nm is obtained in a laser oscillator. By using four identical Nd：YAG laser modules, an output power of 3.1 kW and beam quality of 17 mm＆#12539;mrad with an optical-optical efficiency of 25.8% is demonstrated in a master oscillator power-amplifier system.     

Fluorescence spectrum,thermal properties,and continuous-wave laser performance of the mixed crystal Nd：Lu0.99La0.01 VO4

The fluorescence spectrum and thermal properties of the mixed crystal Nd：Luo.gvLa~.o1VO4 are determined. The strongest emission peak located at 1065.6 nm had a full width at half maximum （FWHM） of 2.1 nm. Continuous-wave （CW） laser performance is demonstrated by a compact planar planar cavity that is end- pumped by a diode laser. The laser output characteristics are investigated by using output couplers with different transmissions. A maximum CW output power of 8.09 W was obtained at an incident pump power of 19.4 W, which corresponds to an optical-to-optical conversion efficiency of 41.7% and a slope efficiency of 54.6%. The dependence of optimum transmission on pump power is calculated theoretically and is found to be consistent with experimental results.     

High efficiency,high power QCW diode-side-pumped Nd：YAG ceramic laser at 1064 nm based on domestic ceramic

A high efficiency, high power diode-side-pumped quasi continuous wave （QCW） Nd：YAG ceramic rod laser at 1064 nm based on the domestic transparent ceramic is reported. The average output power of 961 W is achieved with double ceramic rods by means of a symmetrical convex-convex cavity. The optical-to-optical conversion efficiency is 38.3% and the slope efficiency is 45.3%. To the best of our knowledge, this is the highest level of efficiency achieved for the domestic Nd：YAG ceramic rod laser.