1137 nm长波掺镱光纤激光器的出光实验

分别使用976 nm半导体激光器和1040 nm光纤激光器作为泵浦源,实现了1137 nm长波光纤激光器的出光,输出功率均超过百mW。激光器采用相同的线性腔结构,高反光栅和低反光栅的反射率分别为99.6%和39.7%,增益介质是一段8 m长的掺镱光纤,纤芯直径5 m。当976 nm半导体泵浦功率为912 mW时,1137 nm激光输出功率为182 mW,对应的斜率效率为28.5%;当1040 nm激光功率为1.59 W时,输出的1137 nm激光功率为278 mW,斜率效率约为25%。在此基础上对两种泵浦方式进行了对比分析。     

一种结构新颖的L波段掺铒光纤激光器

提出了一种结构新颖的L波段环形腔掺铒光纤激光器。用掺铒光纤作为增益介,采用980nm激光器作为前向抽运源,利用起偏器和偏振控制器获得L波段激光,利用光环形器将后向的放大自发辐射再引入铒光纤的前端,重复利用。当抽运功率为103mW时得到了阈值功率约为23．87mW,输出功率达6．34mW的激光输出,斜率效率约为8．05％,与没有重复利用后向放大自发辐射谱的掺铒光纤激光器做比较,该结构对L波段掺铒光纤激光器的性能有明显的提升作用。对于长度不合适的铒纤,在没有重复利用后向放大自发辐射谱时没有获得激光输出;而在利用后向放大自发辐射后,在阈值功率约为88mW时得到了激光输出,从而很好地证明了上述结论。     

掺镱双包层光纤激光器的径向偏振振荡

通过在腔内放置汇聚型布儒斯特角轴锥体,并对增益光纤采用双端泵浦, 实验上实现了掺镱双包层光纤激光器的径向偏振模振荡.对增益光纤的末端做了斜角抛光,抑制了光纤端面间的寄生振荡,减小了在低泵浦功率下被放大的自发辐射光份额.该激光器的域值约为175 mW,斜率效率13.8%,激发波长约1085 nm.当泵浦功率达到最大值460 mW时,获得了39 mW的激光输出功率,其光束偏振纯度和圆柱形对称性有显著改善.     

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     

光纤光栅F-P标准具选模单频环形腔光纤激光器

 讨论了光纤光栅法布里-珀罗(F-P)标准具选模光纤激光器的单频运转原理，并研制了全光纤结构单频掺Er³⁺光纤环形激光器。实验中采用两个976 nm激光二极管双向泵浦作为泵浦源，高掺杂浓度掺Er³⁺光纤作为增益介质，以行波腔消除空间烧孔效应，利用光纤光栅F-P标准具窄带选模特性，当泵浦光功率为36 mW时，得到了稳定的单频激光输出。实验中使用了长5和3 m的掺杂光纤，在泵浦光功率为145 mW时输出功率分别为19和42 mW，光-光转换效率分别为13%和29%，斜率效率分别达到了16%和33%。输出谱线3 dB带宽0.01 nm，无跳模现象。     

高功率全光纤光载微波信号功率放大器

为获得可应用于光载微波雷达系统的高功率双频激光源,用1 064nm窄线宽Nd∶YAG单块非平面环形腔激光器作为单频种子源,其输出分为两路,一路直接耦合入光纤,另一路经声光移频,与未移频的光束合束后获得中心频差为150 MHz、功率为20mW的双频激光.利用以半导体激光泵浦和掺Yb3+石英光纤为增益介质的3级主振荡功率放大系统对双频固体激光器输出的双频激光进行放大,获得50.3W的双频放大输出,光束质量因子为1.30,第三级主放大斜效率为74%.双频成分的幅度比、频差在放大过程中得到保持,拍频调制深度及信噪比等特性也未有恶化.双频光纤功率放大器在频差稳定和高功率输出等方面均有良好的表现.     

780W全光纤窄线宽光纤激光器

高功率窄线宽光纤激光器在相干探测、功率光谱合成等方面具有广泛的应用前景.分析了高功率窄线宽光纤激光器中受激布里渊散射效应的抑制方法,以及正弦相位调制光谱展宽理论.采用正弦相位调制技术将单频激光器的线宽展宽至2.9 GHz,通过三级放大结构对输出功率为50 mW的窄线宽种子源进行放大,实现了中心波长1064.34 nm、线宽2.9 GHz、最大功率780 W的激光输出,光—光转换效率79%,光束质量M2x=1.44,M2y=1.43.分析了相位调制前后输出功率提高的原因,认为正弦相位调制增加的纵模降低了光纤中的功率谱密度,提高了输出激光的受激布里渊散射阈值,促使相位调制后的输出功率大幅提高.该激光器的输出功率仅受限于抽运功率,进一步提高抽运功率,有望实现更高功率的窄线宽光纤激光输出.     

光纤复合环形腔单模激光器的研究

单模光纤激光器在光通讯和光传感中具有广阔的应用前景。分析了复合腔光纤激光器的构成及单模的实现特点,提出了一种新颖的光纤复合环形腔激光器结构,并对其进行了实验研究。该激光器使用了波长为980nm的半导体激光器作为泵浦源。三个腔长均为2m,彼此之间的腔长差为1～2mm的光纤环形滤波器与主谐振腔构成复合腔。此激光器在波长为1562nm处得到了线宽小于0.1nm的单模激光输出,输出的光功率可达到1mW。该激光器的阈值为5mW,斜率效率为4%。     

高重复频率飞秒掺镱光纤放大器

 数值分析了掺镱单模光纤放大器的最佳增益光纤长度，并在实验上对掺镱单模光纤放大器和光栅对压缩器进行了研究。以最大平均输出功率为7 mW、重复频率为25.4 MHz、脉宽为56 ps的被动锁模环形腔掺镱光纤激光器作为种子脉冲，用250 mW的976 nm单模半导体激光器分别泵浦3种不同长度的掺镱单模光纤，对种子光进行放大，并用光栅对压缩器对放大后的脉冲在不同光栅距离上进行了压缩实验研究。当掺镱单模光纤长度为1.2 m时得到了较好的放大效果，种子脉冲被放大到140 mW，相应的增益为13 dB，放大后的单脉冲能量为5.5 nJ。在光栅距离为14.1 cm时获得了最短440 fs的脉冲，压缩后的功率为43 mW，相应的峰值功率为3.8 kW。     

单频纳秒脉冲全光纤激光器实现300 W平均功率输出

搭建了一台主振荡功率放大（MOPA）结构的单频脉冲全光纤激光器。通过对线宽为 20 kHz 的连续单频激光器进行强度调制,获得了重复频率 10 MHz、脉宽约 8 ns、平均功率约 0.5 mW 的单频脉冲种子激光。采用多级掺镱光纤放大器对脉冲种子激光进行级联放大,获得了平均功率 300.8 W 的高功率激光输出。目前,激光器输出功率仅受限于泵浦功率,有望通过增加泵浦功率进一步提高输出功率。     

An Efficient Single-Frequency Yb-Doped All-Fiber MOPA Laser at 1064.3 nm

An efficient narrow-linewidth single-frequency(SF) Yb-doped all-fiber master oscillator power amplifier(MOPA)laser operating at 1064.3 nm is demonstrated experimentally.A ring cavity SF fiber laser is used as the seed source for the MOPA system and the Yb-doped fibers are employed as the gain medium or the saturable absorber.The SF operation is observed to be stable without mode hopping.The highest output power of 266 mW is obtained under the 400 mW pump power with the corresponding slope efficiency of 66.2%.The linewidth of the amplified output laser is approximately 1 kHz and its optical signal-to-noise ratio is over 45 dB.     

Single-frequency, single-polarization ytterbium-doped fiber laser by self-injection locking

We demonstrated a stable single-frequency, single-polarization operation of ytterbium-doped fiber laser. As a novel practical method to realize single-polarization operation of fiber distributed Bragg reflector (DBR)laser, we proposed self-injection locking (SIL) with an active fiber ring feedback cavity. The laser has high output power exceeding 15 mW, wavelength of 1053.20 nm, and side-mode suppression ratio greater than 60 dB. The SIL fiber laser shows the improvements in output power and side-mode suppression compared with the fiber DBR laser. No mode-hopping is observed within 2 hours.     

An all-fiber type Er~(3+)/Yb~(3+) co-doped fiber laser

In this paper, a distributed Bragg reflection (DBR) type Er~(3+)/Yb~(3+) co-doped fiber laser of high output power and high slope efficiency was developed. Its gain medium was a 4.45-m-long Er3+/Yb3+ co-doped fiber. When it was pumped by a 1064-nm Nd:YAG, the linewidth of output laser was measured as 0.072 nm by 3 dB and 0.192 nm by 25 dB at 1552.08 nm. The maximum output power was measured as 69 mW. Its power stability was < 5%, side mode suppression ratio was 59 dB, and the output wavelength stability was ±0.01 nm. The laser had a threshold of 12 mW and a slope efficiency of 22%.     

980 nm Yb-doped single-mode fiber laser and its frequency-doubling with BIBO

A quasi-three-level Yb-doped single-mode fiber laser at 980 nm by adopting two 0° fiber ends as cavity mirrors generated a total output power of 1.32 W with the slope efficiency of 75.3%. The fiber length was 36.5 cm close to the optimal theoretical fiber length. The corresponding optical conversion efficiency was 66% from the incident pump power at 946 nm to the laser power at 980 nm. Through frequency-doubling with BIBO crystal, a total output power of 15 mW at 490.8 nm was obtained.     

Efficient operation of diode-pumped single-frequency thulium-doped fiber lasers near 2 micro m

Efficient operation of diode-pumped single-frequency fiber lasers at wavelengths from 1740 to 2017 nm has been demonstrated by using a very short piece of newly developed single-mode active fiber, i.e., heavily thulium-doped germanate glass fiber. At 1893 nm, the single-frequency fiber laser has a pump threshold of 30 mW, a slope efficiency of 35%, and maximum output power of 50 mW with respect to the launched power of single-mode pump diodes at 805 nm. To the best of our knowledge, this is the highest lasing efficiency achieved in single-frequency fiber lasers operating near 2 micro m. Frequency noise of the single-frequency fiber laser at 1893 nm has been characterized and compared with that of single-frequency fiber lasers at 1 and 1.55 micro m.     

Single-frequency thulium-doped distributed-feedback fiber laser

We have successfully demonstrated a single-frequency distributed-feedback (DFB) thulium-doped silica fiber laser emitting at a wavelength of 1735 nm. The laser cavity is less than 5 cm long and is formed by intracore UV-written Bragg gratings with a phase shift. The laser is pumped at 790 nm from a Ti:sapphire laser and has a threshold pump power of 59 mW. The laser has a maximum output power of 1 mW in a single-frequency, single-polarization radiation mode and is tunable over a few nanometers. To the best of the authors' knowledge, this is the first report of a single-frequency DFB fiber laser that uses thulium as the amplifying medium. The lasing wavelength is the longest demonstrated with DFB fiber lasers and yet is among the shortest obtained for thulium-doped silica fiber lasers.     

Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystal with a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-μm fiber coupled laser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiency was 16%. With a 100-μm fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser was obtained with a slope efficiency of 29%.