用于高精度光纤陀螺的宽带掺铒光纤光源

综述了掺铒超荧光光纤光源的国内外研究发展现状,详细探讨了单程前向、单程后向、双程前向、双程后向等几种典型的光源结构;分析了掺铒超辐射型光纤光源的输出特性与泵浦光波长、泵浦功率、光纤长度以及光学反馈的关系;并介绍了当前为改善光源带宽、平均波长稳定性以及输出功率这三个主要参数以满足高精度光纤陀螺的需求所做的一系列探索及研究现状,指出了其技术难点,对掺铒超荧光光纤光源的研究具有一定的参考价值。     

Spectral characteristics of high-power 1.5 μm broad-bandsuperluminescent fiber sources

The spectral variation of spontaneous emission from erbium-doped single-mode fibers is studied with the aim of producing high-power (more than 5 mW), broadband (in excess of 10 nm) amplified spontaneous emission sources for fiber gyroscope applications. In particular, the evolution of spectral shape and center wavelength with fiber length and output power in the previously unstudied high-power regime where saturation effects dominate is demonstrated. A visibility curve for a potential twin-peaked nonresonant erbium-doped fiber gyroscope source with a short (210 μm) coherence length is also presented     

泵浦功率对掺铒光纤光源性能影响的实验研究

超荧光掺铒光纤光源技术是高精度光纤陀螺的关键技术之一,其优劣直接影响陀螺的性能。在完成铒纤长度优化设计的基础上,实验分析了泵浦功率对掺铒光纤光源平均波长以及带宽的影响,同时在-20-60℃的温度范围内,测量了不同泵浦功率条件下掺铒光纤光源平均波长、带宽和输出功率随温度的漂移。实验结果表明,当泵浦功率在60—120mW范围内时,平均波长受泵浦功率的影响约为-6．5ppm／mW,可以根据光纤陀螺对输出功率和带宽大小的要求在此范围内选择合适的泵浦功率。最终装配样机的平均波长的长期稳定性（6h）达到5ppm（峰-峰值）,短期稳定性（1h）达到2ppm,可以在此基础上定制合适的光纤光栅滤波器,对ASE光谱进行滤波,使谱形满足高精度光纤陀螺的要求．     

全光纤同带泵浦宽带掺镱超荧光光纤光源的实验研究

采用自制的1018 nm光纤激光器做泵浦源,建立了全光纤同带泵浦的宽带掺镱超荧光光纤光源实验系统,首次利用同带泵浦对单程前向结构的超荧光产生进行了深入的实验研究。研究结果表明:基于同带泵浦的掺镱超荧光光源的斜率效率高达88%,半极大全宽度（Full Width at HalfMaximum,FWHM）最宽可以达到14.81 nm。掺镱光纤长度的改变,将影响超荧光光源的最大输出功率、斜率效率及中心波长,随着掺镱光纤长度的增加,最大输出功率和斜率效率下降,中心波长红移。固定光纤长度,改变泵浦功率,随着泵浦功率的增加,超荧光的最大功率和FWHM增加,光谱中心波长偏移很小。在掺镱光纤长度为5.7 m时,超荧光光源的最宽FWHM为14.81 nm,斜率效率在80.3%以上,输出功率的波动小于1%,没有驰豫振荡出现。     

双程后向结构掺铒光纤超荧光光源研究

通过编制1套图形界面的模拟分析软件,对双程后向结构掺铒光纤超荧光光源有关输出功率、带宽和平均波长特性进行了理论模拟。结果表明,通过选取适当的掺铒光纤长度,总能实现光源的平均波长不依赖于泵浦功率的高稳定性。并报道了研制的双程后向结构掺铒光纤超荧光光源。     

High-gain superfluorescent neodymium-doped single-mode fiber source

High-brightness, low-coherence sources are required in a number of optical sensor applications, particularly the fiber-optic gyro. An efficient superfluorescent, neodymium-doped phosphate glass fiber source has been developed which fulfils this requirement. The fiber shows a high-gain efficiency at 1.053 μm of 1 dB/mW pump power and this permits pumping with an 810 nm single-stripe AlGaAs laser diode to obtain >5 mW CW output power at a wavelength of 1.053 μm for only 45 mW of pump power     

Characteristics comparison of Er-doped double-pass superfluorescent fiber sources pumped near 980 nm

The Er-doped superfluorescent fiber sources (SFS's) pumped near 980 mm in double-pass forward and backward configurations are compared for the first time. The results indicate that a double-pass backward SFS is superior to the forward counterpart in many aspects: higher output power at various lengths of erbium-doped fiber, better pump-power dependent mean wavelength stability, and larger linewidths at various fiber mirror reflectance.     

A depolarized Er-doped superfluorescent fiber source with improvedlong-term polarization stability

In a backward Er-doped superfluorescent fiber source (SFS), we report the observation of large mean wavelength variations (>100 ppm) induced by external perturbations of the fiber birefringence. These previously unreported variations, which need to be reduced to the ppm level for high-accuracy fiber-optic gyroscope applications, are shown to originate first from polarization-dependent gain induced by the polarized pump source, and second from a slight polarization dependence of the SFS wavelength division multiplexing (WDM) coupler and fiber isolator. We demonstrate that these effects can be substantially reduced by incorporating two Lyot fiber depolarizers in the source. The new depolarized SFS exhibits short-term mean wavelength stability of ±2.5 ppm and a long-term drift of ±3 ppm. The latter is probably due mostly to slow variations in the Er-doped fiber temperature, which can be eliminated with a simple temperature control to ~0.1°C     

Polarized Superfluorescent Fiber Sources

We report the theoretical and experimental performance of new, linearly polarized superfluorescent fiber sources (SFS). Internal polarization is produced either by splicing a fiber polarizer at an optimum location along a standard Er-doped SFS or by using a single-polarization Er-doped fiber. Numerical simulations predict that when operated in the backward, forward, or double-pass configuration, these SFSs produce nearly twice the power in the desired linear polarization as a standard, unpolarized SFS. This efficiency figure depends weakly on the polarizer location and extinction ratio, but requires a low polarizer insertion loss ( < 0.5 dB). Laboratory prototypes of a backward and a forward polarized SFS are presented that exhibit a power output in the desired linear polarization about 1.75 times larger than that of an unpolarized SFS, and an extinction ratio in excess of 17.5 dB.     

超辐射掺铒光纤光源平均波长稳定性分析

为了解决高精度光纤陀螺要求长时间的标度因数稳定性到10-5以下,必须确保高精度光纤陀螺所采用的掺铒超辐射光纤光源具有非常稳定的平均波长.从超辐射掺铒光纤光源的结构出发,推导出其平均波长主要受到温度、抽运功率、抽运波长、抽运光偏振态以及光纤陀螺返回光功率的影响.详细分析了以上因素对于超辐射掺铒光纤光源平均波长稳定性的影响,并介绍了消除或者减小这些影响因素的措施.同时还总结了提高超辐射光纤光源的平均波长稳定性的相关技术,采用这些技术可以获得平均波长随温度变化系数±0.05×10-6/℃的高稳定性掺铒超辐射光纤光源.对于掺铒超辐射光纤光源在高精度光纤陀螺中的实际应用具有指导意义.     

双程后向结构铒光纤超荧光光源的理论分析

本文数值模拟了掺铒光纤超荧光光源的物理过程,对单程前向／后向结构光源的理论与实验结果进行了比较,两者达到了很好的符合,包括在输出信号频谱分布上,文中给出了有关双程后向结构光源特性的理论分析,首次表明,通过优化反射镜参数,在稳定的前提下,双程后向结构光源具有优于其他结构光纤光源的频带宽和泵浦率。     

采用光纤滤波器的高波长稳定性掺铒光纤光源

研究了双程后向结构掺铒光纤光源的平均波长对泵浦功率的赖性。实验结果表明,通过采用掺铒光纤滤波器以及选择合适的泵浦功率,平均波长随泵浦功率的变化能够降低到-9 ppm/mW。在-40~+60℃ 温度范围内,光纤光源的平均波长不稳定性小于33 ppm(峰峰值)。采用5 m 长的掺铒光纤、泵浦功率55mW 与泵浦波长974.2nm 时,光纤光源输出光波的谱宽达到17nm,功率达5.83mW。     

Clad-pumped Yb,Er codoped fiber lasers

Double-clad and Yb,Er codoped fiber lasers emitting at eye-safe wavelengths (>1.5 μm) have been investigated by varying the codopant concentrations, core modifiers, fiber length, and the spectrum of the diode pump. With a proper composition, the laser output contains only one lasing wavelength, at 1.6 μm. Highest slope efficiency greater than 60% for this three-level system, emitting only at 1.6 μm, has been obtained by using a 20-m-long, double-clad and codoped fiber with the core and clad diameters of 6.3 and 300 μm, respectively. By tradeoff of slope efficiency fur higher output power, a 30-m-long fiber is considered to be the best choice     

前向抽运双级双程掺铒光纤宽带光源

提出并实现了一种前向抽运双级双程结构的 1 5 5 μm超荧光光纤光源(SFS)。通过恰当地选择光源的各个参数,包括两段掺铒光纤(EDF)的长度和两级抽运光的功率,在保证平均波长稳定的情况下,获得了同时具有大功率和宽带特性的超荧光输出。这种结构的光源可以很好地满足高精度光纤陀螺(FOG)对光源的要求     

A highly efficient polarized superfluorescent fiber source for fiber-optic gyroscope applications

We demonstrate a novel polarized superfluorescent fiber source (SFS) that increases the output power in the desired polarization by a factor of 1.96 over that of an unpolarized SFS at the same pump. This is achieved by inserting a polarizer at the optimal point in the bidirectionally pumped erbium-doped fiber of an unpolarized SFS. Stable pump-power-dependent mean wavelength operation and less sensitivity to the insertion loss, important for fiber-optic gyroscope applications, are obtained in this configuration.     

掺铒光纤ASE宽带光源的实验研究

掺铒光纤ASE源是一种优良的宽带光源,受到人们广泛关注.实验研究了掺铒光纤ASE宽带光源单、双程结构后向ASE输出光谱特性,当泵浦光中心波长为1480 nm时,分别考察了掺铒光纤长度、泵浦光功率对后向ASE输出平坦区间宽度和平坦度的影响.通过对两种结构下后向ASE输出光谱的分析比较发现,双程结构在L波段长波长处,尤其是1570～1620 nm波长范围,功率显著提升,从而使得ASE光谱的平坦区间宽度增大,平坦度提高.所得实验结果将为掺铒光纤ASE宽带光源的研制提供依据.     

Prediction of gain peak wavelength for Er-doped fiber amplifiersand amplifier chains

We present a simple rule for predicting the gain peak wavelength (GPW) of an Er-doped fiber amplifier. For a given fiber type, the GPW is determined solely by the operating gain per unit length. Using this rule coupled with a simple Er-doped fiber amplifier model and measured modeling parameters, the GPW is predicted for a particular Er-doped fiber. The result is verified by direct measurement in a fiberloop. We demonstrate that the gain peak does not vary with pump power, pump wavelength or signal power as long as the gain per unit fiber length is fixed. Extension of this theory to include the wavelength dependences of other components in an amplifier chain is also discussed and demonstrated     

高平均波长稳定性超荧光光纤光源

光纤陀螺要求其光源具有高功率、宽谱输出,同时在大温度范围内仍具有好的平均波长稳定性。为了满足-45℃~70℃大温度范围的应用需求,采用双程后向抽运、法拉第旋转反射、带通滤波等技术手段,对光纤材料和器件进行大温区全局优化,以改善超荧光光纤光源的平均波长稳定性。理论分析了不同中心波长和带宽的带通滤波器以及光纤长度等参量对平均波长稳定性的改善效果,以及和光谱带宽的关系。按照设计结果选择滤波、光纤长度等参量,通过对-45℃~70℃全温区范围进行系统全局优化设计,得到输出功率为32mW,功率稳定性为0.65%,光谱带宽为12.5nm,光源平均波长变化量为23.5×10-6。结果表明,平均波长稳定性在0.5×10-6/℃以下的高稳定性超荧光光纤光源中,32mW输出功率非常高;所得的0.2×10-6/℃是115℃大温差范围、30mW以上超荧光光纤光源中非常优异的平均波长稳定性指标,满足光纤陀螺对光纤光源的要求。     

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 1542nm to 1559nm) is got. The MWFS has a channel spacing of ～0. 8 nm which satisfies ITUstandard. The intensity fluctuation among channels is less than 0.5dB,and the extinction ratio of all channels is above 14dB. This kind of MWFS should be useful to wavelength division multiplexing systems.     

High-power semiconductor edge-emitting light-emitting diodes foroptical low coherence reflectometry

A new semiconductor source was designed for optical low coherence reflectometry, increasing the sidelobe-free dynamic range by three to five orders of magnitude compared to conventional EELED's. Reflectivities internal to an optical fiber circuit separated by as much as eight orders of magnitude can now be detected at wavelengths of 1.3 and 1.55 μm, using compact semiconductor sources. For applications not requiring sidelobe-free operation, the same devices can be operated at high current (200 mA) and low temperatures (near 0°C) to produce nearly 1 mW of 1.5 μm emission coupled into single-mode fiber. The resulting wavelength spectrum is smooth, enabling fiber-based absorption spectral measurements