Experimental Research on Erbium-doped Superfluorescent Fiber Source

The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated.By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port,the pump power dependent on MWS becomes independent of pumped EDF length.This is a novel phenomenon that hasn’t been reported up to now,and should be helpful to SFS fabrication and theory analysis.By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ～20 channels (from 1 542 nm to 1 559 nm) is got.The MWFS has a channel spacing of ～0.8 nm which satisfies ITU-standard.The intensity fluctuation among channels is less than 0.5 dB,and the extinction ratio of all channels is above 14 dB.This kind of MWFS should be useful to wavelength division multiplexing systems.

Demonstration of multi-Watt all-fiber superfluorescent source operating near 980 nm

The superfluorescent Yb-doped fiber source operating near 980 nm is studied. The design requirement is theoretically discussed aiming to suppress the amplified spontaneous emission around 1030 nm in the 980-rim superfluorescent fiber source. Based on the theoretical study, a multi-Watt, all-fiber, bi-directional, pumped, superfluorescent source operating near 980 nm is designed and experimentally demonstrated for the first time, to the best of our knowledge. The recorded 8.38-W combined output power is obtained with a 3-dB bandwidth about 3.5 nm. The power scaling of the 980-nm superlfuorescent fiber source is limited by the parasitic laser oscillation.

Numerical Simulation on Broad-band Er-doped Superfluorescent Fiber Source Filter Using Long Period Chirped Fiber Grating

Given is an analysis of broad-band Er-doped superfluorescent fiber source(EDSFS)filter using long period chirped fiber grating by transmission matrix method.For our EDSFS attenuated amplitude demand and the flattened wavelength range demand,proposed are the key factors of designing such filters of high performances.The simulation result demonstrates that such type filters have an enough attenuation to flatten the dramatic increase in output amplified spontaneous emission(ASE)in the wavelength range of 1529nm^1535nm by choosing conformable fiber filter parameters such as chirped degree,original period,induced index change,length of the fiber filter,and then broad-band EDSFS could be achieved.

An improved four-dimensional variation source term inversion model with observation error regularization

Aiming at the Four-Dimensional Variation source term inversion algorithm proposed earlier,the observation error regularization factor is introduced to improve the prediction accuracy of the diffusion model,and an improved Four-Dimensional Variation source term inversion algorithm with observation error regularization(OER-4DVAR STI model)is formed.Firstly,by constructing the inversion process and basic model of OER-4DVAR STI model,its basic principle and logical structure are studied.Secondly,the observation error regularization factor estimation method based on Bayesian optimization is proposed,and the error factor is separated and optimized by two parameters:error statistical time and deviation degree.Finally,the scientific,feasible and advanced nature of the OER-4DVAR STI model are verified by numerical simulation and tracer test data.The experimental results show that OER-4DVAR STI model can better reverse calculate the hazard source term information under the conditions of high atmospheric stability and flat underlying surface.Compared with the previous inversion algorithm,the source intensity estimation accuracy of OER-4DVAR STI model is improved by about 46.97%,and the source location estimation accuracy is improved by about 26.72%.

利用光源投影坐标系处理SFS中的自阴影问题

对于由明暗恢复形状(SFS)问题来说,自阴影的存在是影响其重构效果的因素之一,应该加以特殊的处理。为了使自阴影的处理不延伸破坏其他区域,并能保护整体的重构形状,提出了一套从阴影分割、坐标系变换到数据拟合的自阴影处理方法。该方法使用了根据图像平面以及光源方向定义的光源投影坐标系,以降低自阴影处理问题的复杂性,从而使得可以通过逐行恢复图像内跨各自阴影数据区段高度变化量的方式来实现其基本处理要求,并可采用抛物线拟合的方法来完成重构的阴影区形状与其他部分的光滑连接。实验表明,该方法能有效地改善SFS的重构形状。

Experimental investigation of the stimulated Raman scattering effect in high-power nanosecond superfluorescent fiber source

In this work,we experimentally investigate the dependence of the stimulated Raman scattering(SRS)effect on the seed linewidth of a high-power nanosecond superfluorescent fiber source(ns-SFS).The results reveal that the SRS in the ns-SFS amplifier is significantly influenced by the full width at half maximum(FWHM)of the ns-SFS seed,and there is an optimal FWHM linewidth of 2 nm to achieve the lowest SRS in our case.The first-order SRS power ratio increases rapidly when the seed’s linewidth deviates from the optimal FWHM linewidth.By power scaling the ns-SFS seed with the optimal FWHM linewidth,a narrowband all-fiberized ns-SFS amplifier is achieved with a maximum average power of 602 W,pulse energy of 24.1 mJ and corresponding peak power of 422.5 kW.This is the highest average power and pulse energy achieved for all-fiberized ns-SFS amplifiers to the best of our knowledge.

基于扎根理论的众包物流商业模式研究--以SF同城为例

随着人们收入的提高以及消费能力和消费意愿的增强,即时配送行业开始高速发展,一种新兴的众包物流模式应运而生。众包模式着力优化服务质量、提升用户体验,解决城市“最后一公里”的即时配送问题。SF同城依托SF的口碑和流量,通过搭建全场景、全时段、全距离的配送服务平台,为客户提供定制化服务,打造品牌口碑与流量闭环,助力其提升市场竞争力。因此,我国众包物流模式应从平台精细化、产业智能化、服务标准化、场景多样化及市场全面化等方面进行优化,以进一步促进即时配送的健康有序发展。

2-kW-level superfluorescent fiber source with flexible wavelength and linewidth tunable characteristics

The superfluorescent fiber source(SFS)with tunable optical spectrum has shown great application potential in the sensing,imaging,and spectral combination.Here,we demonstrate for the first time a 2-kW-level wavelength and linewidth tunable SFS.Based on a flexible filtered SFS seed and three stages of fiber amplifiers,the output power can be scaled from the milliwatt level to about 2 kW,with a wavelength tuning range of 1068–1092 nm and a linewidth tuning range of 2.5–9.7 nm.Moreover,a numerical simulation is conducted based on the generalized nonlinear Schr?dinger equation,and the results reveal that the wavelength tuning range is limited by the decrease of seed power and the growth of amplified spontaneous emission,whereas the linewidth tuning range is determined by the gain competition and nonlinear Kerr effects.The developed wavelength and linewidth tunable SFS may be applied to scientific research and industrial processing.

In-band pumping avenue based high power superfluorescent fiber source with record power and near-diffraction-limited beam quality

High power superfluorescent fiber sources(SFSs), which could find wide applications in many fields such as middle infrared laser generation, Raman fiber laser pumping and spectral beam combination, have experienced a flourishing time in recent years for its unique properties, such as short coherence length and high temporal stability. The challenge for performance scalability of powerful SFS mainly lies on the physical issues including parasitic laser oscillation and modal instability(MI). In this contribution, by employing in-band pumping avenue and high-order transverse-mode management, we explore a high power SFS with record power, near-diffraction-limited beam quality and spectral manipulation flexibility. An ultimate output power of 3.14 kW can be obtained with high temporal stability and a beam quality of M^2= 1.59 for the amplified light. Furthermore, the dynamics of spectral evolutions, including redshifting of central wavelength and unsymmetrical broadening in spectral wings, of the main amplifier with different seed linewidths are investigated contrastively. Benefiting from the unique high pump brightness and high MI threshold of in-band pumping scheme, the demonstrated system also manifests promising performance scaling potential.

High Stability Multi-Wavelength Source by Using Synchronized Etalon Filter in Superfluorescent Fiber Source

We demonstrate a new technique to generate a high stability multi-wavelength fiber source by inserting a synchronized etalon filter in superfluorescent fiber source. Multi-wavelength source can easily be obtained over the EDF gain region with the proposed schedule. By partially feedback diffracted spontaneous emission into erbium doped fiber medium, greater output power, extinction ration and narrower linewidth for each channel than that simply using the spectrum slicing technique is easy obtained. Stab...

中红外侧面泵浦合束器及全光纤超荧光光源的研制(特邀)

中红外超荧光光源具有光谱范围宽、空间相干性好、时域稳定性高等特点,应用前景广泛,但受限于中红外侧面泵浦合束器,目前普遍利用空间结构泵浦产生。文中根据拉锥光纤侧面耦合的原理,在125μm包层直径的无源双包层氟化物光纤上实现了中红外光纤侧面泵浦合束器的研制,该合束器泵浦光耦合效率达82.3%,可承受的最大泵浦功率达87.5 W。通过在中红外增益光纤上制得侧面泵浦合束器,实现了全光纤中红外超荧光光源产生,前后向输出的中红外超荧光最高功率和为91.09 mW(后向输出53.67 mW,前向输出37.42 mW),输出光谱范围从2702 nm覆盖至2830 nm。在中红外超荧光总输出功率为33.03 mW时,获得了108 nm的最宽20 dB带宽。文中实现的中红外全光纤超荧光光源克服了以往空间泵浦复杂度高、调节难的问题,对推动中红外超荧光光源的进一步功率放大具有重要意义。

大功率高效率掺铒超荧光光纤光源及其应用

采用光纤反射环镜和双程后向结构 ,得到了最大输出功率 30 .6mW、光光转换效率 4 2 .0 %的大功率、高效率全光纤掺铒超荧光光源 (SFS) 利用串接光纤光栅 (FBG)和光纤型F P腔 ,对其进行光谱分割 ,得到了稳定的多波长输出

用于光纤光栅制作的监控光源掺Yb^(3+)超荧光光源的研究

根据石英中Yb3+ 发射光谱在 10 30nm发射截面比 10 5 3nm附近大得多而导致在 10 30nm附近出现荧光峰值的特点 ,采用抑制 10 30nm附近荧光峰值、提高 10 5 3nm附近荧光输出的方法 ,在装置中使用反射圈对超荧光进行了研究 ,在 82mW泵浦功率下得到了 19mW的超荧光 ,其中 10 5 3nm附近荧光输出达到 - 31.7dBm .用这种方法研制的超荧光能监控中心波长从 10 13nm到 10 93nm范围内、反射率从 30dB到 60dB所有光纤光栅的制作 .

铒纤长度对掺铒光源性能影响的实验研究

实验演示了铒纤长度的选择对1550nm双通后向超荧光掺铒光纤光源(DPBSFS)的平均波长以及谱宽性能的影响,特别是对平均波长稳定性的影响,实验分析了-20℃～60℃之间光源固有平均波长的变化,最终得到了铒纤固有热系数以及整个样机的平均波长稳定性随铒纤长度变化的实验曲线,对超荧光掺铒光纤光源的器件选择和优化设计具有重要参考价值.

掺稀土元素光纤超荧光光源

本文介绍了超荧光光纤光源的基本原理、基本结构和研究进展。报道了我们研制的大功率掺Yb3 +

L波段掺铒光纤超荧光光源和放大器研究

通过优化铒光纤长度,获得了平坦谱宽达30nm(0.7dB)的L波段超荧光光源,该光源具有7.21dBm的输出功率。在此基础上,研究L波段放大器增益特性,通过对铒光纤长度的进一步优化,用1480nm激光器作前向泵浦源,实验上获得了波长从1565nm^1595nm范围平坦的增益带宽,小信号增益可达22dB。

基于掺铒超荧光光纤光源的高精度光纤陀螺

针对高精度光纤陀螺的需求,采用一种在1 550 nm波段长波反射的截止型薄膜滤波器研制出高性能的掺铒超荧光光纤光源,通过仿真确定了滤波器的特征参数,在-40℃^+60℃的温度范围内,光源中心波长稳定性为2.58×10-6℃,输出功率稳定性优于1%.研究了这种光源的强度噪声,并采用一种噪声相减技术对光纤陀螺的噪声进行抑制,光纤陀螺的随机游走系数减小约20%.在此基础上,研制出高精度闭环全保偏光纤陀螺样机.Allan方差分析显示,研制出的样机零漂为0.004 5(°)/h、随机游走系数为0.003 5(°)/h12、标度因素误差小于11×10-6,已能满足高精度陆用惯性系统的要求.

大功率、高效率、高消光比铒光纤多波长超荧光光源

采用改进的反射式Mach Zehnder干涉滤波器 ,对双程后向结构掺铒光纤超荧光光源 (DPBSFS)分别进行光谱分割和光谱预分割 ,构建了两种结构的多波长超荧光光纤光源 (MWSFS) ,波长间隔为～ 0 .8nm时 ,在 15 5 0nm附近 (15 42～ 15 5 9nm) 2 0个波长的功率波动小于 0 .5dB 其中前者消光比高达 2 7dB ;后者消光比～ 18dB ,在泵浦光功率为 72 .8mW时 ,最大输出功率 2 5 .3mW ,光光转换效率高达 34.8% 改变Mach Zehnder干涉仪的臂长差 ,采用光谱预分割技术 ,得到 15 5 0nm附近波长间隔～ 0 .4nm、消光比～ 16dB的 5

高功率Er/Yb共掺光纤超荧光光源

为了获得高功率超荧光输出,采用6个976nm的LD,通过一个光纤束耦合器同时抽运Er/Yb共掺光纤,分别研究了单程后向结构和双程后向结构超荧光光源的输出特性。采用单程后向装置,当抽运功率为957mW时,输出功率为120.4mW,斜率效率达到17.5%。在双程后向结构的实验装置中加入4m掺Er光纤,有效地将超荧光的3dB带宽拓展到88nm。

一种简单的高功率L波段超荧光光源

采用双程前向结构,在一根高浓度掺铒光纤中实现了功率高达13.13mW(11.18dBm)、平均波长为1578.53nm的L波段高功率超荧光输出,在1570nm^1620nm间的功率高于9.38mW。可满足分布式光纤光栅传感、DWDM等由C波段向L波段扩展的带宽及功率需求,同时与C波段光匹配后,可得到功率高于20mW的C+L波段宽带高功率光输出。其中采用普通耦合器制作的光纤圈反射器,将后向的C波段ASE重新引回光纤中,提高了抽运源的利用效率和光纤输出光的稳定性,同时分析了光源的输出功率、平均波长、稳定性等随光纤长度、抽运功率的变化特征,对于光源的应用设计提供参考。