High power diode-pumped passively Q-switched and mode-locking Nd:GdVO4 laser at 912 nm

A high power diode-end-pumped passively Q-switched and mode-locking (QML) Nd:GdVO₄ laser at 912 nm was demonstrated for the first time, to the best of our knowledge. A Z-type laser cavity with Cr⁴⁺:YAG crystals as the intracavity saturable absorber were employed in the experiments. Influence of the initial transmission (T_U) of the saturable absorber on the QML laser performance was investigated. Using the T_U = 95% Cr⁴⁺:YAG, as much as an average output power of 2.0 W pulsed 912 nm laser was produced at an absorbed pump power of 25.0 W, then the repetition rates of the Q-switched envelope and the mode-locking pulse were ~ 224 kHz and ~ 160 MHz, respectively. Whereas the maximum output power was reduced to 1.3 W using the T_U = 90% Cr⁴⁺:YAG, we obtained a 100% modulation depth for the mode-locking pulses inside the Q-switched envelope.     

Diode-pumped passively Q-switched 912 nm Nd:GdVO4 laser and pulsed deep-blue laser by intracavity frequency-doubling

A diode-end-pumped passively Q-switched 912 nm Nd:GdVO₄/Cr⁴⁺:YAG laser and its efficient intracavity frequency-doubling to 456 nm deep-blue laser were demonstrated in this paper. Using a simple V-type laser cavity, pulsed 912 nm laser characteristics were investigated with two kinds of Cr⁴⁺:YAG crystal as the saturable absorbers, which have the different initial transmissivity (T_U) of 95% and 90% at 912 nm. When the T_U = 95% Cr⁴⁺:YAG was used, as much as an average output power of 2.8 W 912 nm laser was achieved at an absorbed pump power of 34.0 W, and the pulse width and the repetition rate were ∼ 40.5 ns and ∼ 76.6 kHz, respectively. To the best of our knowledge, this is the highest average output power of diode-pumped passively Q-switched Nd³⁺-doped quasi-three-level laser. Employing a BiBO as the frequency-doubling crystal, 456 nm pulsed deep-blue laser was obtained with a maximum average output power of 1.2 W at a repetition rate ∼ 42.7 kHz.     

4.44 W of CW 515 nm green light generated by intracavity frequency doubling Yb:YAG thin disk laser with LBO

We demonstrate the generation of 515 nm green laser with diode-pumped Yb:YAG thin disk by intracavity frequency doubling of type-I phase-matched LiB₃O₅(LBO) in a V-type cavity at room temperature. A continuous-wave (CW) output power of 4.44 W at 515 nm was obtained. Optical-optical efficiency of 515 nm green laser is 14.6%. The fluctuation of green laser was 1.6% at the maximum output power in 0.5 h. Thermal lensing effects in Yb:YAG thin disk are investigated too.     

A kilowatt level diode-side-pumped QCW Nd:YAG ceramic laser

We demonstrate a kilowatt level Quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG ceramic laser at 1064 nm. The laser system adopts a master oscillator power amplifier scheme (MOPA). The master oscillator contains two diode-pumped laser modules. Under the pump power of 2000 W, an output power of 686 W was obtained. After amplified by an identical ceramic laser module, a maximum output power of 1020 W was obtained under a total incident pump power of 3433 W, corresponding to an optical-optical conversion efficiency of 29.7%. At the maximal output power, the repetition frequency was measured to be 1 kHz and the pulse width was 114 μs. To the best of our knowledge, this is the first time to realize QCW side-pumped Nd:YAG ceramic laser system with output power above 1 kW.     

Diode-end-pumped passively Q-switched Nd:Y0.8Lu0.2VO4 laser with Cr:YAG crystal

A diode end-pumped passively Q-switched Nd: Y_0.8Lu_0.2VO₄ laser with a Cr⁴⁺: YAG crystal is first demonstrated in this paper. The maximum continuous wave (CW) output power of 5.59 W is obtained at the incident pump power of 13.07 W with the output transmission T = 20%, resulting in an optical-to-optical efficiency of 42.7%. For Q-switching operation, the measured pulse duration of 8.5 ns, the pulse energy of 45.24 μJ and the peak power of 5.32 kW are respectively obtained for the output transmission of 50% when the Cr⁴⁺: YAG crystal is used with an initial transmission (T₀) of 60%.     

LD end-pumped intracavity frequency doubled Yb:YAG laser

A laser diode end-pumped 10 at.% doped Yb:YAG microchip crystal intracavity frequency doubled all solid-stated green laser is reported in this paper. Using one plano-concave resonator, with the pump power of 1.2 W, 44.2 mW TEM₀₀ continuous wave (CW) laser at 525 nm was obtained, the optical conversion efficiency was about 3.7%. When a Cr:YAG crystal with initial transmission of 95.5% inserted in the resonator, the maximum output power of 6.4 mW, pulse duration width of 49.1 ns, pulse repetition rate of 2.45 kHz, and peak power of 53.1 W at 515 nm were achieved when the pump power was 1.2 W. The wavelength changed from 525 nm to 515 nm and the threshold was only 725 mW.     

Light scattering and 2-μm laser performance of Tm:YAG ceramic

The scattering effect of Tm:YAG ceramic has been investigated and the scattering coefficient at 1064 nm wavelength is measured to be 0.014 cm⁻¹. Furthermore, a high power Tm:YAG ceramic laser with a slope efficiency of 10.7% has been built, which is end-pumped at a central wavelength of 805 nm. The 2-μm maximum output power is 7.1 W with an optical-optical conversion efficiency of 7.2%.     

108 W Nd: YAG ceramic laser with birefringence compensation resonator

The quartz rotator's effective birefringence compensation for ceramic Nd:YAG rods has been first demonstrated. Furthermore, a high output power continuous-wave laser is presented based on an optimized resonator made up of four Nd:YAG ceramic rods. By an appropriate design of the resonator, an output power of 108 W at 1064 nm is obtained. The corresponding optical-to-optical conversion efficiency is 16.8% and the slope efficiency is 28.1%. Meanwhile, the numerical analysis for output power is detailed.     

Dual-polarization electro-optical Q-switched ceramic laser

A dual-polarization electro-optical Q-switched Nd:YAG ceramic laser was studied. By selecting the appropriate size of calcite crystals, the dual-polarization Q-switched pulse was achieved by characteristics of calcite crystal. Experimental results show that compared with the traditional single-polarization electro-optical Q-switched laser, insertion loss is reduced, dynamic to static ratio is greatly improved, thermally induced birefringence of electro-optical Q-switched Nd:YAG ceramic laser is effective compensated. The output power of 19 W and the pulse width of 13 ns are obtained at the repetition rate of 1 kHz and pumped power of 144 W. The dynamic to static ratio is 71%. The results formed the basis for the further development of the high power and high efficiency ceramic red laser.     

678 nm RTP electro-optical Q-switched ceramic laser

The RTP electro-optical Q-switched ceramic laser at the wavelength of 678 nm with narrow pulse width is studied. We used the laser diode arrays side-pumped Nd:YAG ceramic crystal with 1.1 at% Nd doping and dimensions of Φ3 mm × 50 mm, designed folding cavity parameters, and discussed the variation of the beam radius in the ceramic crystal and frequency doubling crystal with the thermal focal length of ceramic crystal or KTP crystal. By using double RTP crystals as electro-optic Q-switch and KTP crystal type II phase matching for intracavity frequency-doubling, a narrow pulse width electro-optical Q-switched Nd:YAG ceramic laser was obtained. The output energy of 0.9 mJ and the pulse width of 41.6 ns at 678 nm are obtained at the repetition rate of 1000 Hz and pumped power of 144 W. The results formed the basis for the further development of the high power and high efficiency ceramic red laser.     

In-band pumped Er:YAG ceramic laser with 11 W of output power at 1645 nm

We report on a high power polycrystalline Er:YAG ceramic laser in-band pumped by a cladding-pumped Er, Yb fiber laser wavelength locked at 1532 nm with a volume Bragg grating. Using 1.0 at % Er³⁺-doped ceramic as the gain medium and an output coupler of 10% transmission, the laser had a threshold pump power of ∼1.5 W and generated 11 W of continuous-wave output at 1645 nm for 23.3 W of incident pump power at 1532 nm, corresponding to a slope efficiency with respect to incident pump power of 51%.     

High-power polycrystalline Er:YAG ceramic laser at 1617 nm

We report on the efficient operation of a high-power erbium-doped polycrystalline Er:YAG ceramic laser at 1617 nm resonantly pumped by a high-power 1532 nm Er,Yb fiber laser. Lasing characteristics of Er:YAG ceramics with different Er3+ concentrations are evaluated and compared. With an output coupler of 15% transmission and 0.5 at. % Er3+-doped YAG ceramic as the gain media, the laser generates 14 W of output power at 1617 nm for 28.8 W of incident pump power at 1532 nm, corresponding to a slope efficiency with respect to incident pump power of 51.7%.     

High-power diode-pumped mode-locked Yb:YAG ceramic laser

A high-power diode-pumped passively mode-locked Yb:YAG ceramic laser was demonstrated. An average output power of 3.80W with a pulse duration of 433 fs at a repetition rate of 90.9MHz was obtained at a wavelength of 1050 nm using a 2% output coupler. A peak power of 96.5kW was also obtained. To the best of our knowledge, these are the highest reported average power and peak power for a diode-pumped mode-locked Yb:YAG ceramic laser.     

Two-pass amplification of CW laser by Nd/Cr:YAG ceramic Active mirror under lamp light pumping

The concept of an Active mirror with transparent Nd/Cr:YAG ceramics is proposed. A new ceramic material pumped by an arc-metal-halide lamp has been experimentally implemented. CW-laser light generated in a 1064 nm Nd:YAG micro-tip oscillator was amplified by an Active mirror made of Nd/Cr:YAG ceramic and pumped by CW arc-lamp light. The saturation power density of the Nd/Cr:YAG ceramic was lower than that of Nd:YAG because the stimulated-cross-section and lifetime were effectively enhanced by the sensitization of Cr ions. The maximum output laser power while keeping spatial beam quality was up to 3 W with an input lamp power of 9 W; the resulting optical-optical conversion efficiency of 33% was close to the theoretical prediction of nearly 50%.     

Diode-pumped Yb:KYW thin-disk laser operation with wavelength tuning to small quantum defects

We present continuous wave laser operation of a diode-pumped Yb:KY(WO₄)₂ thin-disk laser with 10.7 W output power, M² = 1.3 and an optical efficiency of 49% at room temperature. Wavelength tuning in a range of 64 nm and lasing with a quantum defect of 0.6% is demonstrated.     

Single-frequency Yb:YAG non-planar ring oscillator fiber amplifier source at 1030 nm

We report on amplification of a single-frequency Yb:YAG non-planar ring oscillator using Yb-doped fibers. The amplifier system operated at 1030 nm with up to 18.7 W output power, 75% slope efficiency and an M²-value better than 1.1.     

219.3 W CW diode-side-pumped 1123 nm Nd:YAG laser

We demonstrate a high power continuous wave (CW) diode-side-pumped Nd:YAG laser operating at 1123 nm with a plano-plano configuration. By means of precise coating, a single 1123 nm wavelength is achieved. Under the pump power of 1080 W, an output power of 219.3 W is obtained, which corresponds to an optical-optical conversion efficiency of 20.3%. To the best of our knowledge, this is the highest output power for CW 1123 nm laser based on Nd:YAG crystal.     

Nd:YAG陶瓷与单晶4F3/2–4I13/2跃迁的弱谱线多波长激光性能对比

报道了基于半导体激光端面抽运Nd:YAG的⁴F_3/2–⁴I_13/2 跃迁的弱谱线多波长激光输出. 实验对比了透明陶瓷与单晶材料的激光输出特性, 表明透明陶瓷和单晶材料荧光谱强度的略微差异, 导致了多波长输出时相同两个波长之间的激光强度比在两种材料中的差异. 基于两种耦合输出镜片, 激光阈值都在2 W左右. 在13.5 W的抽运功率下, 基于Nd:YAG透明陶瓷获得了输出功率4.05 W、强度比1 :2的1338与1356 nm双波长激光和输出功率3.65 W、强度比13 : 1的1356与1414 nm 双波长激光, 斜率效率分别达33.9% 和31.9%.     

An 8.1 W diode pumped solid-state quasi-continuous-wave yellow laser at 589 nm by intracavity sum-frequency mixing generation

We report an L-shaped symmetrical co-folding-arm plane-plane diode pumped solid-state yellow laser at 589 nm by using intracavity sum-frequency mixing. By carefully designing the cavity and employing various techniques to optimize the laser’s specifications, a quasi-continuous-wave (QCW) free-oscillation yellow laser source, which has an average output power of 8.1 W, a beam quality factor of M² = 2.3, and a repetition rate of 1.1 kHz, is developed. The generation of yellow laser at 589 nm is achieved by intracavity sum-frequency mixing between the laser lines at 1319 nm and 1064 nm of an Nd:YAG laser in a KTP crystal. To the best of our knowledge, the 8.1 W output at 589 nm is higher than any other diode pumped solid-state yellow laser generated by intracavity sum-frequency generation so far.     

High-efficiency continuous-wave and Q-switched diode-end-pumped multi-wavelength Nd:YAG lasers

We demonstrate high-efficiency diode-end-pumped multi-wavelength Nd:YAG lasers for continuous-wave and Q-switched operation. For the continuous-wave case, the Nd:YAG laser oscillates at 1.06 and 1.3 μm simultaneously; the maximum output power of 2.0 W (M² = 1.3) and 3.6 W (M² = 1.8) have been achieved at the incident pump power of 20.3 W, with the respective average slope efficiencies of 12.0% and 21.4%, for the lines of 1.06 and 1.3 μm, respectively. For the Q-switched operation, we achieve the average output power of 1.3 W (M² = 2.7) at 1.06 μm and 2.0 W (M² = 3.0) at 1.3 μm with the corresponding peak power of 10.2 and 4.2 kW under an incident pump power of 20.3 W.