High average and peak power femtosecond large-pitch photonic-crystal-fiber laser

We report on the generation of high-average-power and high-peak-power ultrashort pulses from a mode-locked fiber laser operating in the all-normal-dispersion regime. As gain medium, a large-mode-area ytterbium-doped large-pitch photonic-crystal fiber is used. The self-starting fiber laser delivers 27 W of average power at 50.57 MHz repetition rate, resulting in 534 nJ of pulse energy. The laser produces positively chirped 2 ps output pulses, which are compressed down to sub-100 fs, leading to pulse peak powers as high as 3.2 MW.     

26 nJ picosecond solitons from thulium-doped single-mode master oscillator power fiber amplifier

We report on an all single-mode master oscillator power fiber amplifier delivering high energy picosecond solitons at 1960 nm. The Bragg stabilized and self-starting oscillator delivers 62 pJ transform-limited pulses at 11.2 MHz pulse repetition frequency. Solitons are amplified in a core-pumped single-mode heavily thulium-doped fiber up to 26 nJ. The average and peak power are 291 mW and 7.4 kW, respectively. Pulses remain transform limited without significant self-phase-modulation distortion. We discuss the limitations of picosecond pulse amplification in a core-pumped single-mode fiber amplifier.     

128 W单频线偏振光纤放大器特性研究

高功率单频激光在激光雷达、光谱学、精密测量等领域具有广阔的应用前景.采用中心波长为1064 nm、光谱线宽为20 kHz、偏振消光比（PER）高于20 dB的单频线偏振分布式反馈光纤激光器做种子源（尾纤输出功率约为10 mW）,利用种子注入主振荡功率光纤放大技术,通过两级级联放大实现了128 W高功率单频、线偏振、近衍射极限单模连续激光输出.主放大器光-光效率达到83%,PER高于12 dB.采用分段温控技术有效地提高了光纤中的受激布里渊散射（SBS）阈值,实验中未观察到明显的放大自发辐射和SBS现象,进 关键词： 掺Yb光纤放大器 主振荡功率光纤放大 单频 线偏振     

Single-frequency, single-mode, plane-polarized ytterbium-doped fiber master oscillator power amplifier source with 264 W of output power

We present a single-frequency, single-mode, plane-polarized ytterbium-doped all-fiber master oscillator power amplifier source at 1060 nm generating 264 W of continuous-wave output power. The final-stage amplifier operated with a high gain of 19 dB and a high conversion efficiency of 68%. There was no evidence of rollover from stimulated Brillouin scattering even at the highest output power, and the maximum output was limited only by the available pump power.     

High power single-mode large-mode-area photonic crystal fiber laser with improved Fabry-Perot cavity

An Yb3+-doped double-clad large-mode-area photonic crystal fiber (LMA PCF) laser with 103-W single mode continuous-wave output power is demonstrated using an improved Fabry-Perot (F-P) configuration.The slope efficiency of 83.2% and good beam quality (M2 = 1.2 ± 0.1) are achieved without any thermo optical problems,dichroic mirror surface damage,and drop of the slope efficiency in this system.     

High-power tunable single-frequency single-mode erbium:ytterbium codoped large-core fiber master-oscillator power amplifier source

We present a cladding-pumped single-frequency, single-mode erbium:ytterbium codoped fiber master-oscillator power amplifier source generating up to 151 W of continuous-wave output power at 1563 nm with 33% slope efficiency and 20 dB gain. This source was also tunable and had a stable operation range of 1546 to 1566 nm at an output power level in excess of 125 W. The doped fiber exploited a large-core design for improved power handling and mitigation of stimulated Brillouin scattering. There was no sign of having stimulated Brillouin scattering even at the highest power. Despite a large core (V = 12), the output beam was nearly diffraction limited (M2 = 1.1). The source showed slight rollover at over 100 W of output power because of the onset of emission from ytterbium, centered at 1060 nm.     

High output power Erbium-Ytterbium doped cladding pumped fiber amplifier

The performance of a high output power Erbium-Ytterbium doped fiber amplifier (EYDFA) pumped by a 927 nm laser diode are proposed and experimentally investigated. The EYDFA provides a flat gain and output power higher than 23 dBm in the wavelength region from 1545 to 1566 nm using a double-pass configuration. A broadband fiber Bragg grating is used in the double-pass EYDFA to allow a double-propagation of the test signal in the gain medium and thus improves the gain and output power characteristics of the amplifier. The maximum output power of 390 mW is obtained at the maximum 927 nm pump power of 4.1 W which translates to a power conversion efficiency of about 10%.     

High-energy temporally shaped nanosecond-pulse master-oscillator power amplifier based on ytterbium-doped single-mode microstructured flexible fiber

We present a versatile master-oscillator power amplifier system at 1053?nm in the few-nanoseconds regime meeting the high-level requirements of high-power laser facility front ends. Thanks to temporal shaping, more than 1.5?mJ pulse energy at 1?kHz with an excellent optical signal-to-noise ratio has been obtained in a single-mode 40?μm core flexible fiber.     

High average power ultra-fast fiber chirped pulse amplification system

We report on a high-gain diode-pumped ytterbium-doped fiber-amplifier system delivering pulse energies in the 100-μJ range at high repetition rates (32 kHz) with nearly-diffraction-limited beam quality (M²∼1.7) at a 1060-nm center wavelength. Femtosecond seed-laser pulses are stretched in a commercially available single-mode fiber and compressed after amplification to subpicosecond pulse duration. In a multimode Yb-doped fiber amplifier we have demonstrated average powers of up to 22 W and single-pulse energies of up to 130 μJ. Received: 16 August 2000 / Revised version: 4 September 2000 / Published online: 8 November 2000     

High power pulse amplification of ytterbium-doped double-clad fiber amplifier

By solving a set of time-dependent equations, the characteristics of the ytterbium-doped double-clad fiber amplifier are presented. Besides the steady state in the fiber of the upper-state population, pump power and amplified spontaneous emission without the input signal, the dynamic characteristics of the high power Gaussian pulse amplification like the evolution of pulse waveform distortion, upper-state population distribution and stored energy and pulse energy of the amplifier under the forward and backward pump,are simulated. The relations between the output pulse energy of the amplifier and the different input pulse peak power or pump power are also discussed. The models and results can provide important guide for the design and optimization of the high power pulse amplification.     

High peak power operation and harmonic generation of a single-polarization, Yb-doped photonic crystal fiber amplifier

We report on the use of a single-polarization, 41 μm core-diameter, intrinsically single-mode photonic crystal fiber (PCF) to obtain high peak power (up to 800 kW), 1 ns-duration pulses in a 100:1 linearly polarized, intrinsically single-mode (M²  1.2) output. By transmitting the PCF output through nonlinear crystals, we also obtained efficient second, third, and fourth harmonic generation resulting in peak power >400 kW in the visible (green, 531 nm) and 200 kW in the UV (265.5 nm). To our knowledge these results represent the highest peak power obtained in a linearly polarized output from a fiber and the highest peak power in the visible and UV obtained through harmonic generation of the direct fiber output.     

高功率全光纤保偏主振荡功率放大型光纤激光器的实验研究

进行了全光纤保偏主振荡功率放大型光纤激光器的实验研究. 采用两级级联放大的方式, 利用纤芯为5 μupm 的小芯径双包层保偏光纤, 在最大抽运功率为88 W 时实现了67 W的1083 nm保偏激光输出, 纤芯内的激光功率密度约为3.4 W/μupm², 光-光转换效率为76%．分析结果表明, 进一步提高抽运功率有望获得更高功率的激光输出．     

高峰值功率大模场全光纤脉冲放大器

报道了一种由纤芯直径分别为15μm和25μm的大模场光纤组成的全光纤脉冲放大器模块.当注入脉冲宽度为10 ns,重复频率为1 Hz.光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300μJ.此外,实验研究了该放大器模块输出的时间特性.研究发现:由于受激布里渊散射(SBS)效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值.     

High power supercontinuum generation in a nonlinear ytterbium-doped fiber amplifier

High power supercontinuum generation with 70 W average output power in a nonlinear ytterbium-doped fiber amplifier is demonstrated using all-normal dispersion, all-fiber master oscillator power amplifier configuration. The supercontinuum covers from 1064 nm to beyond 1700 nm with spectral flatness better than 12 dB and 67.3% optical to optical conversion efficiency. The almost uniform spectral power density across the whole continuum is more than 70 mW/nm and the nanosecond bursts output have an effective peak power of 82.7 kW.     

Medium power single-mode single-wavelength fiber laser

Medium-power, single-mode, single-wavelength fiber laser working at room temperature using a polarization-maintaining erbium-ytterbium co-doped fiber as the gain medium, and an un-pumped elliptical core erbium-doped fiber as a saturable absorber to reduce linewidth and mode hopping of the lasing wavelength is reported. The effects of length, erbium ion concentration, and polarization-maintaining property of the saturable absorber were explored. The output power of the laser was more than 100 mW and the lasing line was stable for more than 3 h with an intensity fluctuation of less than 0.2 dB. The laser linewidth (FWHM = Full width at half maximum) was 7.5 MHz and the signal to noise ratio was more than 50 dB. The output of the laser was measured using an optical spectrum analyzer (OSA) of resolution 1.25 GHz and a scanning Fabry-Perot spectrum analyzer (SFPSA) of resolution 6.7 MHz.     

高峰值功率大模场全光纤脉冲放大器

报道了一种由纤芯直径分别为15 μm和25 μm的大模场光纤组成的全光纤脉冲放大器模块。当注入脉冲宽度为10 ns,重复频率为1 Hz,光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300 μJ。此外,实验研究了该放大器模块输出的时间特性。研究发现：由于受激布里渊散射（SBS）效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值。     

Over 200 W average power tunable Raman amplifier based on fused silica step index fiber

A high-power tunable Raman Amplifier is presented. The seed signal (varying from 1118 nm to 1130 nm in wavelength) was generated in a tunable Raman oscillator and fed into the Raman amplification stage. A conversion efficiency of up to 86 % was achieved and a maximum output power of over 200 W was measured. The Raman gain coefficient for the amplifier fiber was measured to be 0.76×10^?14 m/W. Furthermore, the measured output power was compared with values obtained from simple mathematical model and a good agreement up to the highest output power of amplified signal was achieved.     

High power semiconductor laser array with single-mode emission

The semiconductor laser array with single-mode emission is presented in this paper. The 6-μ m-wide ridge waveguides (RWGs) are fabricated to select the lateral mode. Thus the fundamental mode of laser array can be obtained by the RWGs. And the maximum output power of single-mode emission can reach 36 W at an injection current of 43 A, after that, a kink will appear. The slow axis (SA) far-field divergence angle of the unit is 13.65°. The beam quality factor M² of the units determined by the second-order moment (SOM) method, is 1.2. This single-mode emission laser array can be used for laser processing.     

7.3-W single-frequency master-oscillator fiber power amplifier with China-made double-clad fiber

A narrow-linewidth master-oscillator fiber power amplifier system was presented, in which an ultrastable,continuous-wave, single-frequency laser was adopted as the master oscillator and a China-made Yb-doped large-mode-area fiber was used as the power amplifier medium. The system generates single-frequency radiation up to 7.3 W at 1064-nm wavelength with 39% slope efficiency and 26% optical-optical power conversion efficiency. The spectral characteristics as well as the suppression of amplified spontaneous emission were discussed in detail.     

同带抽运高效率光纤放大器

以光纤光栅为谐振腔搭建了波长为1020 nm的光纤激光器,并通过两级级联放大获得了590 mW的最大输出功率. 利用获得的波长为1020 nm的激光进行了波长为1064 nm种子光同带抽运放大,实验研究了不同增益光纤长度时放大器的输出功率和转换效率. 当增益光纤长度为8.5 m时,放大器最大输出功率为385 mW,斜率效率为81%. 进行了波长为976 nm的半导体激光器直接抽运波长为1064 nm种子光的实验. 在增益光纤长度最优时,其斜率效率为56.4%. 实验结果表明,同带抽运方式比传统抽运方式具有更高的转换效率. 研究结果可为波长为1020 nm的激光高功率放大和波长为1064 nm的光纤激光高功率同带抽运放大提供一定的参考. 关键词： 同带抽运 光纤放大器 斜率效率