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.     

High efficiency Tm fiber laser of seed amplification

We use all-fiber single-mode lasers as seed source, amplifiers and pump laser coupling amplifier has been experimentally investigated, respectively. The maximum output power is 10.4 W, with the slope efficiency of 54.4% when the seed laser power is 1 W, and the slope efficiency is 48.7% when the seed laser power is 2 W. The slope efficiency of this scheme is higher than that of the all-fiber amplifier. This can be explained by the loss of pump power at the splice dots. The wavelength of the fiber amplifier is 1947.6 nm, the same as the seed laser's, with a linewidth of 2 nm. We estimate the beam quality to be M² = 2.39, clearly indicating nearly diffraction-limited beam propagation.     

35 W high power all fiber supercontinuum generation in PCF with picosecond MOPA laser

We demonstrate 35 W high power all fiber supercontinuum generation by pumping photonic crystal fiber (PCF) with a 57.7 W picosecond fiber MOPA. The picosecond fiber MOPA pumped supercontinuum source exhibits an optical-to-optical conversion efficiency of up to 61.7%, covering a spectral range from 600 nm to beyond 1700 nm. The compact and practical configuration of this supercontinuum source has potential to achieve higher power scale together with perfect continuum spectrum.     

一种基于增益调制技术的全光纤化脉冲Yb光纤激光器

以波长为975 nm的半导体激光器作为泵浦源,周期性地脉冲泵浦一个包含Yb掺杂光纤和光纤光栅对的Yb光纤激光器,实现了基于增益调制技术的全光纤化高功率Yb光纤激光器的稳定脉冲输出.在50 kHz重频下,采用20 W的泵浦功率和2.4 μs的泵浦脉冲宽度,获得了1 060 nm波长脉冲宽度仅100 ns的稳定脉冲激光输出,单脉冲激光能量约为20 μJ.以此作为脉冲激光种子进行功率放大,获得了性能稳定的全光纤结构高功率脉冲激光输出,放大后单脉冲能量超过200 μJ,激光放大器斜率效率达到60%.     

国产全光纤结构激光器实现245 W高功率激光输出

 以国产掺镱光纤为增益介质,利用国产泵浦源和光纤器件,构建了主振荡功率放大（MOPA）结构的全国产大功率全光纤激光器。激光器包括10 W种子激光器和高功率放大器两部分。在注入最大泵浦功率为356 W时,获得了245 W波长1 080 nm激光的稳定输出,光-光效率为69%。激光器单次连续出光时间约30 min,功率稳定性在1%以内。目前激光器输出功率受限于泵浦功率,增加泵浦源的数目有望进一步提高输出功率。     

百瓦级全光纤结构单频掺铥主振荡功率放大器

报道了平均功率超过百瓦的单频掺铥全光纤结构主振荡功率放大器。使用线宽小于100kHz、中心波长为1.97μm的单频种子源进行级联放大,主放大器的斜率效率为50%。监测放大器的回光功率和光谱,没有发现受激布里渊散射以及其他非线性效应。通过增加泵浦功率,可以获得更高功率的掺铥单频放大输出。     

1μm全光纤MOPA结构激光器输出特性研究

主振荡功率放大（main oscillation power amplification, MOPA）结构由于其光束质量良好和参数可调的优点,已成为高功率光纤激光器的主流设计之一。为了改善高功率掺镱光纤激光器（ytterbium-doped fiber laser, YDFL）的输出性能,提高系统的光-光转换效率,文中报道了一台基于915 nm泵浦激光器和双包层掺镱光纤（ytterbium-doped fiber, YDF）的MOPA结构全光纤高功率激光器。该高功率光纤激光器由电调制激光二极管（laser diode, LD）泵浦的种子激光器和掺镱光纤放大器（ytterbium-doped fiber amplifier, YDFA）组成。连续光（continuous wave, CW）工作模式下,激光种子源经过YDFA后,实现了中心波长为1 069.96 nm的激光输出,最大平均输出功率可达945.9 W,MOPA激光器整机的斜率效率高达74.12%,具有良好的稳健性。该研究方案对研制高功率MOPA光纤激光器具有参考意义。     

800 mW/1484 nm highly efficient two-cascaded phosphosilicate Raman fiber laser pumped by Nd:YVO4 solid-state laser

Using 1064 nm CW Nd:YVO₄ solid-state laser as a pump, 1-km phosphosilicate fiber and cascaded cavities with two pairs of fiber Bragg grating mirrors for 1239 and 1484 nm, we obtained a CW 800 mW/1484 nm Raman fiber laser (RFL) for an actual incident pump power of about 2 W (Nd:YVO₄ power of 6.90 W). The conversion efficiency is as high as 40%. To the best of our knowledge, this is the highest conversion efficiency of RFL pumped by solid-state laser. The output power instability at 1484 nm in half an hour is less than 3%. In addition, the numerical simulations are also performed. Good agreement between the results of numerical simulation and the results of the experiment has been demonstrated.     

主振荡功率放大结构窄线宽全光纤激光器334 W高功率输出

 搭建了一台全光纤结构的窄线宽高功率掺镱光纤激光器。种子激光的输出功率大于40 mW,线宽窄于100 MHz。采用主振荡功率放大结构三级放大,主放泵浦功率为405 W时得到了334 W的窄线宽高功率激光输出,光光转换效率为82.4%。目前,激光器输出功率仅受限于泵浦功率,增加有效泵浦功率即有望进一步提高输出功率。     

All-fiberized Tm-doped fiber MOPA with 30-W output power

We demonstrate a 30-W all-fiberized laser in a master oscillator power amplifier(MOPA) structure with a central wavelength of 1 950 nm.The laser is a continuous-wave(CW) operation with double-clad Tm-doped silica fiber pumped by pigtailed laser diodes with a central wavelength of 793 nm.The optical-to-optical efficiency of the MOPA system is 37.5% with respect to the total 80-W pump power.The maximal slope efficiency of the system is approximately 43%,which belongs to the main amplifier and exceeds the Stoke limit.No obvious amplified spontaneous emitting(ASE) is observed in the experiment,and the power can be scaled straightforwardly by improving the pump power.     

Four-wave mixing in dual wavelength fiber laser utilizing SOA for wavelength conversion

In this paper, a novel configuration of a wavelength converter is set forth by utilizing a semiconductor optical amplifier (SOA) as a nonlinear gain medium to generate a four-wave mixing (FWM) effect by using a dual wavelength bi-erbium-doped fiber laser that uses an Arrayed Waveguide Grating (AWG) together with two optical channel selector (OSC) as selective elements to function as a dual wavelength switchable pump power. The four-wave mixing (FWM) is produced with a wavelength detuning of 7 nm from the pump and signal which used is as the converted signal at wavelength 1532.8 nm or 1534.5 nm for transferring data from the input signal at wavelength 1547.0 nm. Thus, even though the conversion efficiency is as low as −43 dB, it is still possible for applications as a wavelength converter.     

C-band continuously tunable lasers using tunable fiber Bragg gratings

We report the development of a ring tunable fiber laser based on tunable fiber Bragg gratings (TFBG) integrated with an optical circulator. The TFBG is embedded inside a 3-piont bending device for wavelength tuning. The tunable laser operating in the C-band has power variation, tuning resolution, tuning range and laser line width of ±0.5 dB, 0.5 nm, 25.0 nm and less than 0.05 nm, respectively. As 40 mW of pump power is used, the ring tunable laser has a side mode suppression ratio of 60 dB and a power conversion efficiency of 25%. These specifications ensure the high-quality operation of a tunable laser.     

26W near diffraction limited Q-switched green laser based on a diode-end-pumped master oscillator power amplifier

An efficient acousto-optically Q-switched extracavity frequency-doubled 532nm laser based on a diode-end-pumped master oscillator power amplifier (MOPA) is demonstrated. With a type I non-critically phase-matched LBO, 26W of average power at 532nm in a near diffraction limited mode at a repetition rate of 30kHz was generated under 43W pump power of 1064nm Nd:YVO_{4} laser, which correspond to a frequency-doubling conversion efficiency of 60%.     

Theoretical analysis and heat dissipation of mid-infrared chalcogenide fiber Raman laser

Based on the structure of mid-infrared chalcogenide fiber Raman laser, the nonlinear coupled equations and heat dissipation equations are constructed. The effects of laser parameters including pump power, fiber length, reflectance of output coupler and fiber loss coefficient on laser performance are numerically analyzed. The results show that the Raman laser pumped at 2 μm can operate at high slope efficiency using the optimized structure parameters. In addition, the output laser power decreases dramatically with the increasing of fiber loss coefficient. Moreover, the temperature distributions along the fiber radial and axial directions and the maximum temperature versus launched pump power are calculated according to the heat dissipation equations. The results show that the maximum temperature in the fiber increases dramatically with the increasing launched pump power, which is above 300 °C for launched pump power of 21 W. The above obtained results can be used for theoretical guiding and optimizing design of practical chalcogenide fiber Raman laser.     

全光纤结构高功率主振荡功率放大型单频光纤激光器

研制了一台全光纤结构主振荡功率放大型掺镱单频光纤激光器。该光纤激光器包括种子激光器和级联放大器两部分。种子激光器是自行搭建的环形腔结构的单频窄线宽光纤激光器。在976 nm半导体激光器泵浦下,能够输出线宽为10 MHz量级、波长为1 079.88 nm的单频光,激光功率为10.02 W,光-光转化效率为58.9%,斜率效率为65.3%。     

Effect of steady-state conditions on self-pulsing characteristics of Yb-doped cw fiber lasers

Fiber laser resonator configurations have been analyzed theoretically on the basis of steady-state rate equations to optimize the laser conversion efficiency. Evolution of the pump- and signal powers and the saturated gain coefficient along the length of the laser medium has been simulated for high- and low-finesse resonators in forward- and backward pumping schemes. The corresponding fiber laser configurations have been setup to verify the results of simulation. Backward pumping configuration in an Yb-doped fiber laser has been found to be the most efficient, and in this configuration a maximum cw output power of 10.75 W in single transverse mode with an optical-to-optical conversion efficiency of 62.5% has been achieved. The laser output spectrum was peaked at 1093 nm with full-width at half-maximum (FWHM) line-width of about 9 nm. In the low-finesse resonator configuration, it has been found that experimental observations differ from theoretical simulation results. In this case, output power from both ends ceases to increase linearly beyond 1.8 W, and starts fluctuating due to the onset of strong random self-pulsing phenomenon. Our investigation shows that a non-uniform steady-state gain along the fiber length facilitates the self-pulsing process.     

Passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror

A passively Q-switched Er-doped fiber laser using a semiconductor saturable absorber mirror (SESAM) is demonstrated. Q-switching is observed with the output power produced at a slope efficiency of 29.4% with respect to the absorbed pump power. The maximum average output power of 8.37 mW is achieved. The pulse repetition frequency obtained can be turned from 1.72 to 7.95 kHz. The pulse energy of 17.2 nJ has been obtained at the pump power of 46.75 mW, and the pulse width is 30 μs.     

Novel shooting method with simple control strategy for fiber lasers

A novel shooting method with excellent simple control strategy is developed for solving the failure to convergence of the traditional shooting methods themselves in fiber lasers model. Compared with the published literature, the novel shooting method provides a clear physical understanding method for getting the threshold pump power and the exact results with given random functions in Yb³⁺-doped fiber lasers and Er³⁺-doped fiber lasers. Then, the results in Er³⁺-doped fiber lasers and Yb³⁺-doped fiber lasers demonstrate that the solutions using the novel shooting method has high accuracy of 10⁻⁸ W with several iteration steps, which have extended the applicable range of the end-pumped power even lower than 1 mW pump power. Furthermore, compared with 1480 nm pump for the threshold and slope efficiencies of the Er³⁺-doped fiber lasers, 978 nm fiber lasers can extend wider scope of application and be pump source in the coming future. Finally, the lower threshold and higher slope efficiency at 975 nm than those of 910 nm pump in Yb³⁺-doped fiber lasers, 975 nm pump laser provides for broad band excellent cladding pump source.     

光纤激光泵浦MgO:PPLN高功率中波红外光参量振荡器

为实现高效率、高功率中波红外激光输出,研制基于MgO:PPLN晶体的中波红外光参量振荡器（OPO）,泵浦源为基于主振荡功率放大（MOPA）结构的线偏振掺Yb光纤激光器（YDFL）。实验结果表明:YDFL可实现最高79.1 W的1064.1 nm脉冲线偏振激光输出;在YDFL泵浦下,通过优化输出镜曲率半径和泵浦光束腰直径,该OPO实现最高9.15 W的3.754 μm脉冲激光输出,光光转换效率为11.57%,重复频率为300 kHz,脉冲宽度约为110 ns。     

Theory of Pr:ZBLAN ultraviolet upconversion fiber master oscillator power amplifier

A theoretical study for ultraviolet upconversion fiber master oscillator power amplifier (MOPA) based on the transition from the 4f5d state to the ³H₄ ground state in Pr³⁺:ZBLAN fiber is performed by using steady population rate equations and propagation equations. The variation of the output power with the fiber length of master oscillator and MOPA and the launched pump powers, the dependence of the slope efficiency on the fiber length of master oscillator and MOPA, and the optimum fiber length of MOPA as a function of the launched pump powers, are calculated. Both the output power and the slope efficiency of MOPA are 2-3 times those of the simplex oscillator. It is found that the UV upconversion fiber MOPA system can effectively improve the output power and the slope efficiency of laser.