Dispersion-compensating Raman/EDFA hybrid amplifier recycling residual Raman pump for efficiency enhancement

We experimentally demonstrate a novel concept of the dispersion-compensating Raman/erbium-doped fiber amplifier hybrid amplifier recycling residual Raman pump for increase of overall power conversion efficiency. The proposed dispersion-compensating hybrid amplifier system has only one pump source for Raman amplification in the dispersion-compensating fiber (DCF) and the residual pump power after the DCF is recycled for secondary signal amplification in an erbium-doped fiber cascaded to the DCF. Using the proposed scheme, we achieve the significant enhancement of both signal gain and effective gain-bandwidth by 15 dB (small signal gain) and 20 nm, respectively, compared to the performance of the Raman-only amplifier.     

高精度光纤陀螺用掺铒光纤光源辐照性能试验

针对高精度光纤陀螺的空间应用,理论分析了用于高精度光纤陀螺的不同结构掺铒光纤光源的抗辐照性能,指出了单通后向结构的掺铒光纤光源具有更好的抗辐照性能。对单通后向结构采用不同掺杂浓度的掺铒光纤设计并研制了掺铒光纤光源,在实验室用Co60辐照源进行了大小两个剂量率的辐照试验,监测了掺铒光纤光源平均波长和输出光功率随辐照总剂量的变化,试验结果表明:掺铒光纤掺杂浓度较高时,掺铒光纤光源的抗辐照能力较强;辐照剂量率较小时,掺铒光纤光源功率随辐照总剂量的降低速度更慢。掺杂浓度较高的掺铒光纤光源可以满足高精度光纤陀螺空间应用的要求。     

Amplification properties of erbium-doped solid-core photonic bandgap fibers

A novel erbium-doped photonic bandgap fiber (PBGF) with honeycomb cladding and down-doped solid-core is proposed in this letter. This fiber is more practicable than reported erbium-doped air-core PBGF due to its Gaussian-like field distribution and low confinement loss. Theoretical analysis shows that it can largely improve pump efficiency (gain-to-pump-power ratio) for small pump power and reduce the optimum fiber length by 20%-50% for a wide range of pump powers, compared with erbium-doped step-index fiber.     

双程前向掺铒光子晶体光纤超荧光光源

为了获得高稳定光纤陀螺掺铒光纤光源和改进传统掺铒光纤超荧光光源的输出稳定性,提出和使用掺铒光子晶体光纤作为超荧光光源的增益媒介。构建了双程前向结构掺铒光子晶体光纤超荧光光源, 研究了这种新型光源的输出特性。分析了掺铒光子晶体光纤长度和泵浦功率对光源输出功率、光谱谱宽和平均波长的影响。结果表明,通过选取光纤长度为10 m 和泵浦功率为220 mW,获得了双程前向结构掺铒光子晶体光纤超荧光光源。输出功率为35.4 mW,光光转换效率约16.09%,谱宽为30.9 nm,平均波长为1 548.3 nm。该结果为进一步研究掺铒光子晶体光纤超荧光光源的环境温度稳定性和适应性奠定基础。     

掺铒光纤激光器输出特性的研究

在一定的条件下,确定了掺铒光纤激光器的最佳光纤长度和激光器两个腔镜的最佳反射率,设计出的光纤激光器的输出特性可以得到优化。根据掺铒光纤激光器的速率方程,对线型腔光纤激光器的输出特性进行了理论分析,得到了光纤激光器在稳态条件下的输出功率,阈值抽运功率和斜率效率的解析表达式。对光纤激光器的输出特性进行了数值模拟,得到了泵浦功率为20mw,饵离子掺杂浓度为400 ppm,掺铒光纤长度为1.5m,光纤环形镜反射率为1,光纤光栅反射率为0.5时,光纤激光器的输出功率和斜率效率较大,阈值抽运功率较小。为光纤激光器的优化设计提供了理论依据。     

FP腔掺铒光纤激光器输出特性的解析表示

通过求解掺铒光纤的稳态传输方程，对FP腔掺铒光纤激光器的输出特性进行了分析，获得了用掺饵光纤材料参数和激光器谐振腔结构参数表示的激光器输出光功率、阈值泵浦功率和科率效率的解析表达式。就泵浦光残余反射率对激光器性能的影响进行了分析。     

单级结构C+L波段掺铒光纤宽带光源

报道了利用双向抽运单级掺铒光纤结构研制的高效率C L波段放大自发辐射(ASE)宽带光源。实验表明,该结构在一定的掺铒光纤长度范围内,均可通过调节前后向抽运功率来获得带宽达80 nm(1525~1605 nm)光谱平坦的C L波段宽带光源。光源的抽运转换效率与掺铒光纤长度、前后向抽运功率分配有关。选择所需的最短掺铒光纤长度制作光源,既可以节省光纤,降低成本,还可以提高抽运转换效率。利用该光源结构获得了输出功率为13.5 dBm,抽运转换效率达23.2%的高效率C L波段放大自发辐射宽带光源。     

An erbium-doped multimode optical fiber amplifier

The authors describe the first experimental study of an erbium-doped multimode fiber amplifier. The focus has been to characterize an intermediate core erbium-doped optical fiber, a fiber that is capable of propagating many guided modes at both the signal and pump wavelengths, and to determine the feasibility of using such an active fiber as a multimode fiber amplifier, by measuring its gain, noise, and pump power requirements. For a 2-m length of a 13-μm-core erbium-doped fiber, the authors measured gain as high as 16 dB at a signal wavelength of 1543 nm, with approximately 100 mW pump power (980 nm). For these same test conditions, the smallest excess noise factor β was 42     

掺铒光纤中的后向瑞利散射的研究

本文对掺饵光纤的瑞利散射进行了理论分析，计算了后向瑞利散射光与泵浦功率、掺饵光纤长度、信号光功率的关系，并提出了用隔离器减小后向瑞利散射光的方法。     

多波长布里渊掺铒光纤激光器的结构优化研究

基于受激布里渊散射效应(SBS)和掺铒光纤(EDF)的线性增益机理研究了一种环形腔多波长布里渊掺铒光纤激光器(BEFL)。在该激光器中使用单模光纤作为布里渊增益介质,使用掺铒光纤来放大产生的斯托克斯(Stokes)信号,使该激光器在室温下产生稳定的多波长输出。通过对激光器结构中的环行器和耦合器的位置以及耦合器的接入方式的研究与分析发现:耦合器的接入方式、环行器与耦合器的位置均对激光器的输出有影响。在可调谐光源TLS(布里渊泵浦激光器)的功率大小为14dBm,980nm泵浦激光器的功率大小为23dBm,单模光纤长度为10km的情况下进行了实验测试,结果表明:耦合器的接入方式对BEFL的输出影响很明显,最后给出了详细的测试结果和相应解释。     

高功率高效率掺铒光纤超荧光光源

优化设计了高功率、高效率掺铒光纤超荧光光源的参数。采用商用掺铒光纤,针对双程后向结构,首先仿真了光源输出功率和带宽随掺铒光纤长度的变化,并用对等实验验证了模拟结果,初步确定掺铒光纤长度的优化范围;理论研究了反射镜反射率对光源性能的影响,计算出最佳反射率并模拟了该反射率下光源的输出光谱;实验研究了抽运功率对光源平均波长的影响,确定了优化的抽运功率范围,并进一步确定了掺铒光纤的优化长度。实验选用110mW抽运功率,13.74m掺铒光纤,获得了输出功率为46.9mW的高功率光纤光源,其抽运转换效率可达42.6%,且光源保持了约34.54nm的宽带宽。     

High-power EDFA applied in distributed optical fiber Raman temperature sensor system

In this paper, a high-power erbium-doped fiber amplifier (EDFA) for the temperature sensor system is theoretically designed and experimentally demonstrated. It consists of an erbium-doped fiber that is pumped bidirectionally with two 980-nm high-power laser diodes (LDs). At the EDFA input, an optical isolator (ISO) is used to ensure that the signal pulse transmits forward only. After that, a wavelength division multiplexer (WDM) is employed to combine the forward pump laser (980 nm) and incident optical pulse (1550nm) into the erbium-doped fiber for direct amplification in the optical domain. At the EDFA output, another WDM couples the backward pump laser (980 nm) into the erbium-doped fiber and outputs the amplified optical pulse (1550 nm) with an ISO followed to isolate the backscattering light. According to this structure, we carried out the experiment in the condition as follows. For 980 nm pump LD, the operating current is 590 mA, and the setting temperature is 25℃. For EDFA, the length of erbium-doped fiber is 12.5 m, and the power of 1550 nm input signal is 1.5 mW. As a result, the power of pump LD is 330 mW, and the power uncertainty is 0.5%. The power of EDFA output at 1550 nm is 300 mW, and the power uncertainty is ±3 mW.     

Numerical analysis of concentration quenching model of Er/sup 3+/-doped phosphate fiber amplifier

Based on the homogenous model and inhomogeneous model of concentration quenching of erbium-doped fiber amplifier with high doping concentration, the rate equation and power evolution equation of erbium-doped phosphate fiber are solved numerically and analyzed. The dependence of the calculated gain and noise figure on pump power is compared with experimental data, and the results indicate that the combined model of the two models is in good agreement with experimental data. The relative number of clusters in erbium-doped phosphate fibers is estimated from the numerical analysis, and the optimal doping concentration and length of erbium-doped phosphate fibers are proposed in this paper. By numerical analysis, the results show that with 200-mW/980-nm pump power, an erbium-doped phosphate fiber amplifier with a doping concentration of 4.0/spl times/10/sup 26/ ion/m/sup 3/ and length of 10 cm may reach 27.0-dB gain.     

Spectral dependence of gain and noise in erbium-doped fiberamplifiers

A two-level model of the erbium-doped fiber amplifier is used to analyze the dependence of the amplifier gain saturation, saturated output power, and excess noise factor on pump and signal wavelengths. Measured data are presented confirming that the dependence of the gain, output saturation power, and noise of erbium-doped fiber amplifiers on the signal and pump wavelength can be described by simple equations derived from the model     

Study of distributed erbium doped fiber amplifier

Basing on analyzing distributed erbium-doped fiber amplifier(d-EDFA) of evenly doped density along propagating direction, we put forward two sort d-EDFAs of slowly and linearly variously doped density along propagating direction: one-variation and two-variation d-EDFA. By using convective equations, we study the propagating properties of signal and noise in three sort d-EDFAs. Noise figure, signal-noise ratio, necessary pump and optimal pump period also are studied, under both transparent transmission and optimal doped density.     

Optimum Er3+-doped fiber amplifier design for optical AMvideo signal distribution systems

An investigation into the transmission characteristics of erbium-doped fiber amplifiers for use in optical AM frequency division multiplexing (FDM) video distribution systems is reported. The output signal power and noise characteristics of erbium-doped fibers were measured for different fiber lengths and different pump powers. The experimental results confirm that there exists an optimum amplifier design which gives the maximum distribution number when the pump power and the required video quality are given     

Gain enhancement in L-band EDFA through a double-pass technique

An improvement of gain in the long-wavelength band (L-band) is observed by double passing the forward amplified spontaneous emission and signal in the erbium-doped fiber (EDF) using a circulator, unlike conventional single pass amplification. A gain enhancement as high as 11 dB is obtained for a 1570-nm signal with an input power of -20 dBm at 98 mW of pump power. However, a noise figure penalty of about 2 dB is observed     

Performance reduction and design modification of erbium-doped fiberamplifiers resulting from pair-induced quenching

The authors model the deleterious effect of pair-induced quenching (PIQ) in erbium-doped fiber amplifiers (EDFAs) and describe it in terms of pump power, amplification, and noise factor penalties. With a simple model of how PIQ increases with concentration, they show that to achieve a desired amplification, shorter fiber lengths will require higher pump power, and that there is a lower length limit with realistic pump powers. Rate equations for erbium-ion pairs are formulated with the assumption of one ion per pair completely quenched. Although the results were obtained for EDFAs, the methods and conclusions are also relevant for high-concentration erbium-doped integrated waveguides     

自调Q掺铒光纤激光器动态特性研究

为了研究自调Q掺铒光纤激光器输出动态特性,采用搭建全光纤结构的线形腔和环形腔自调Q掺铒光纤激光器进行了理论分析和实验验证。实验中,当抽运功率达到起振阈值后,随着抽运功率的增加,用示波器观察输出激光,线形腔输出激光依次经历了连续波、自调Q两种运行状态,由于抽运功率的限制,未能再次出现连续波运行状态,而环形腔输出激光则先经历了自调Q运行状态,然后是连续波运行状态;线形腔在抽运功率21mW~190mW的范围内,可获得脉冲宽度8s ~100s范围内可调、重复频率2.5kHz~54kHz范围内可调的自调Q脉冲;环形腔在抽运功率为16.2mW~110mW时,可获得的脉冲宽度在165s左右。结果表明,自调Q掺铒光纤激光器因腔结构的不同,输出激光动态特性也不同;线形腔和环形腔均有自调Q脉冲输出,但线形腔自调Q范围更大。     

Experimental optimization of an erbium-doped super-fluorescent fiber source for fiber optic gyroscopes

Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources(EDSFSs) were combined in one configuration.A 980 nm laser diode pumped the same erbium-doped fiber from both directions using a coupler as a power splitter.The double-pass configuration was achieved by coating the fiber end face.Firstly,an optimal fiber length was found to obtain a high stability of output light wavelength with pump power, and then 1530/1550 nm wavelength division multiplexing was used for spectrum planarization,which expanded the bandwidth to more than 22 nm.The final step was a test of temperature stability.The results show that the rate of the central wavelength change kept to below 3.5 ppm/℃in the range of -40 to 60℃and 1-2 ppm/℃in the range of 20-30℃.Considering all the three factors of the fiber optic gyro applications,we selected 80 mA as the pump current,in which case the central wavelength temperature instability was calculated as 2.70 ppm/℃, 3 dB bandwidth 22.85 nm,spectral flatness 0.2 dB,output power 5.17 mW and power efficiency up to 9.92%.This experimental result has a significant reference value to the selection of devices and proper design of ED-SFSs for the application of high-precision fiber optic gyroscopes.