双纵模窄线宽光纤拉曼放大器

 报道了一台实现了双纵模窄线宽激光输出的光纤拉曼放大器。利用中心波长1 079.7 nm的双纵模窄线宽种子激光器获得了频率间隔1.4 GHz、功率比约3∶1的双纵模输出,各纵模的线宽约为10 MHz;再利用1 031 nm泵浦光对双纵模种子光进行拉曼放大,实现了1.07 W双纵模激光输出。拉曼放大过程中,两个纵模的线宽、频率间隔及功率比保持得很好。     

Different supercontinuum generation processes in photonic crystal fibers pumped with a 1064-nm picosecond pulse

Picosecond pulse pumped supercontinuum generation in photonic crystal fiber is investigated by performing a series of comparative experiments. The main purpose is to investigate the supercontinuum generation processes excited by a given pump source through the experimental study of some specific fibers. A 20-W all-fiber picosecond master oscillator-power amplifier （MOPA） laser is used to pump three different kinds of photonic crystal fibers for supercontinuum generation. Three diverse supercontinuum formation processes are observed to correspond to photonie crystal fibers with distinct dis- persion properties. The experimental results are consistent with the relevant theoretical results. Based on the above analyses, a watt-level broadband white light supercontinuum source spanning from 500 nm to beyond 1700 nm is demonstrated by using a picosecond fiber laser in combination with the matched photonic crystal fiber. The limitation of the group velocity matching curve of the photonic crystal fiber is also discussed in the paper.     

Effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier

Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carded out. The complex Ginzburg-Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber. A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum. The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work.     

高功率光纤端帽实现6 kW激光输出

高功率光纤端帽是kW级光纤激光器必不可少的器件,而实现光纤端帽的低损耗高强度熔接是其关键技术。由于光纤和大尺寸光纤端帽在直径上的巨大差异,二者的熔接不能通过传统熔接机实现。设计并搭建了光纤端帽熔接系统,掌握了多种尺寸的光纤端帽的熔接工艺,成功用于光纤激光器及光纤合束器的高功率输出。实验上利用单模光端帽实现了3.01 kW的激光输出,在未进行主动制冷的情况下温升为7 ℃/kW。利用多模光纤端帽实现了6.08 kW的激光输出,在未进行主动制冷的情况下温升为6 ℃/kW。     

复自相干度度量超连续谱相干性

引入复自相干度来度量同一脉冲产生的超连续谱的相干性, 并对其进行了实验研究. 采用Mach-Zehnder干涉仪, 测量700 ps脉冲抽运光子晶体光纤产生的超连续谱的相干性. 实验测得超连续谱不同波长成分的相干长度均大于40 μm, 在长波区可达225 μm. 超连续谱的整个光谱区域各谱成分的相干度有差异, 但复自相干度的模平均值为0.461, 相干性较好, 可以满足如光测量、光学传感等很多应用.     

七芯光子晶体光纤中百瓦量级超连续谱的产生

采用平均功率为141.6 W的皮秒光纤激光泵浦一段国产七芯光子晶体光纤,获得了平均功率为104.2 W、连续光谱覆盖范围从750至1700 nm以上的超连续谱输出.详细研究了超连续光谱随泵浦功率增加的演变过程,并对基于该七芯光子晶体光纤的超连续谱光源的光谱拓展和功率提升潜力进行相关的分析和讨论.该研究结果对高功率超连续谱光源的发展具有一定的参考价值.     

10kW峰值功率高脉冲能量全光纤结构2μm掺铥光纤激光器

基于增益开关技术在高掺杂浓度掺铥光纤中获得了稳定的2μm种子脉冲激光,输出激光中心波长为1 979.4nm,脉冲重复频率在1~100kHz之间可调,输出脉冲宽度变化范围为60~200ns。采用两级掺铥光纤放大器对该种子脉冲激光进行放大实验,当种子脉冲激光重复频率为20kHz时获得最大输出平均功率为17.2W,输出光谱没有观察到明显的放大自发辐射噪声。最大功率输出时,脉冲宽度为82ns,对应单脉冲能量为0.86mJ,脉冲峰值功率高于10kW。     

偏差与斯特列耳比的极限曲线

通过建立离散波面像差函数与斯特列耳比的最优化问题数学模型,分析了二者的关系,利用最优化方法数值求解得到波面像差峰谷值与斯特列耳比最小值以及波面像差均方根值与斯特列耳比最小值的极限曲线。     

像差与斯特列耳比的极限曲线

通过建立离散波面像差函数与斯特列耳比的最优化问题数学模型 ,分析了二者的关系 ,利用最优化方法数值求解得到波面像差峰谷值与斯特列耳比最小值以及波面像差均方根值与斯特列耳比最小值的极限曲线