掺铒光纤放大器的研究现状与发展趋势

介绍了掺铒光纤放大器 (EDFA)的研究和应用情况 ,指出了掺铒光纤放大器存在的问题及发展方向 ,为掺铒光纤放大器的深入研究提供了有益参考     

800nm LD泵浦掺铒光纤放大器的最佳光纤长度

本文用量子放大器的基本理论,分析了掺铒光纤放大器的激发态吸收(ESA)现象,并得出当存在强烈的ESA时,用800nm LD泵浦掺铒光纤放大器的最佳光纤长度表达式。当用典型值代入计算,其结果与实验确定的值基本相符。最后,提出了实现大增益LD泵浦掺铒光纤放大器的有效方法。     

用于波分复用系统的新型掺铒光纤放大器

介绍了可用于波分复用系统的增益平坦、宽带放大的新型掺铒光纤放大器,文中就其结构、性能和实验结果进行了讨论.对实现掺铒光纤放大器的各种不同技术方案进行了分析,提出了适合波分复用系统的掺铒光纤放大器设计思想,为掺铒光纤放大器的深入研究提供了有益参考.     

共掺铝的掺铒光纤放大器的光谱特性

用Stark能级分裂的变化分析了掺铝改变掺铒光纤放大器(EDFA)光谱特性的原理，并用改进型化学气相沉积法(MCVD)结合溶液浸泡掺杂法制作了采用不同掺铝比例的掺铒光纤，测试了用这几种光纤制作的放大器的自发辐射谱，得出掺铝浓度的提高使荧光谱的峰值往短波长移动，与Stark能级分裂理论分析得到的结果相一致。同时采用截断法测试了两种不同掺铝浓度的掺铒光纤的吸收谱，实验结果表明掺铒光纤中增加铝的含量将提高铒离子浓度，并提高掺铒光纤的吸收系数，减短掺铒光纤放大器中的掺铒光纤长度。高掺铝掺铒光纤放大器具有更宽更平坦的增益谱线，可以适用长距离波分复用(WDM)系统。     

掺铒光纤放大器多信道放大的理论和实验研究

本文用ＭｃＣｕｍｂｅｒ理论从掺铒氟光纤中Ｅｒ３＋的发射截面参数推算出其正确的吸收截面参数,据此从理论和实验上研究了具有平坦小信号增益谱的掺铒光纤放大器在光波波分复用系统中应用时可能存在的问题,得到了理论计算和实验结果相一致的结论;提出采用掺铒氟光纤放大器作为＂掺铒光纤放大器＋光波波分复用＂干线系统中的级联放大器并通过调节其工作点的简单办法实现系统的全程信道增益均衡。     

空间光通信中空间辐射对光纤放大器性能的影响

以60Co为辐射源, 通过地面辐射模拟实验, 对掺铒和铒镱共掺两种光纤放大器的性能变化进行了对比分析。实验结果表明, 在总剂量为40 krad的低剂量轨道辐射环境中, 信号光通过这两种光纤放大器后, 其中心波长及半宽都没有发生显著变化, 这为光纤放大器能够应用于空间光通信提供了保证; 在辐照过程中掺铒光纤放大器的增益下降3.91 dB, 而铒镱共掺光纤放大器的增益下降17.60 dB, 表明镱离子的存在使得铒镱共掺光纤放大器的抗辐射性能要明显弱于掺铒光纤放大器, 这也为不同发射功率下的空间光通信系统在选择合适类型的放大器时提供了一个有益的参考。     

光纤长度优化的高功率铒镱共掺光纤放大器

为了研究不同增益光纤长度下1555nm高功率光纤放大器的输出功率,采用两级混合结构的方法,用掺铒光纤放大器和双包层铒镱共掺光纤放大器分别作为1级预放大器和2级主放大器。掺铒光纤放大器对信号光进行预放大,并提高放大器的信噪比;双包层铒镱共掺光纤放大器为主放大器,其双包层结构可以把更多的多模抽运光耦合进系统。对铒镱共掺光纤的最佳长度做了理论分析和实验验证,在信号光功率为10mW、掺铒光纤放大器的抽运功率为318.58mW、双包层铒镱共掺光纤放大器的抽运功率为11.71W、增益光纤长度为14m时,输出功率取得了2.11W的实验数据。在分析输出信号光谱时发现,L波段附近有放大自发辐射谱出现,这是选择的增益光纤过长导致的。结果表明,在光功率和信号光功率一定时,光纤放大器有一个最佳的光纤长度。这一结果对研究光纤放大器的高功率输出是有帮助的。     

掺铒光纤放大器的研究进展

近几年来,掺铒光纤放大器作为1.5μm通信窗口的光通信新器件,得到了广泛重视。掺铒光纤放大器作为功率放大器、在线中继器或前置放大器,已进入Gbit/s长中距离光通信传输实验阶段。本文介绍了掺铒光纤放大器的基本原理,综述了掺铒光纤放大器的研究进展及最新成果。     

掺铒光纤放大器多信道放大器的理论和实验研究

本文用ＭｃＣｕｍｂｅｒ理论从掺铒氟光纤的Ｅｒ＾３＋的发射截面参数推算出其正确的吸收截面参数，据此从理论和实验上研究了上有平坦小信号增益谱的掺铒光纤放大器在光波波分复用系统中应用时可能存在的问题，得到了理论计算和实验结果相一致的结论：提出采用掺铒氟光纤放大器作为“掺铒光纤放大器＋光波波分复用”干线系统中的级联放大器并通过调节其工作点的简单办法实现系统的全程信道增益均衡。     

掺铒光纤放大器

阐述掺铒光纤放大器(EDFA)的原理和结构，介绍掺铒光纤放大器在密集波分复用(DWDM)传输系统中的应用，掺铒光纤放大器的优缺点以及发展前景。     

Performance optimization of radio-on-fiber systems employing erbium doped fiber amplifier for optical single sideband signals considering intermodulation distortion

The performances of radio on fiber (RoF) systems with a dual-electrode Mach-Zehnder modulator and an erbium-doped fiber amplifier (EDFA) are optimized by numerical equations including the third order intermodulation (IM3) as well as amplified spontaneous emission (ASE) noise. We investigate a signal-to-noise-and-distortion ratio (SNDR) considering fiber dispersion with respect to an input signal power and an EDFA gain in both noise-dominant and third order intermodulation (IM3)-dominant cases. We also verify that the numerical analysis results are well matched with those of a commercial simulator, VPItransmissionMaker. In the analysis results, the optimum input signal power for the maximum SNDR of a RoF system with EDFA was reduced over 8 dB compared with that without EDFA. The dramatic reduction of IM3 power at a receiver was resulted from this decrement of input signal power. Thus, the maximum SNDR of the system with EDFA was obtained over 17 dB at 40 km fiber compared with that of the system without EDFA. In addition, the results showed that the SNDR was efficiently improved by EDFA in the noise-dominant case, while the SNDR improvement was negligible by EDFA in the IM3 dominant case.     

Second-order distortion of amplified intensity-modulated signalswith chirping in erbium-doped fiber

Second-order distortion produced in an erbium-doped fiber amplifier (EDFA) is investigated theoretically and experimentally. Rate equations for intermodulation products are led by the perturbation method. From numerical calculation, it is shown that optimum combinations of input power to EDFA and signal wavelength exist that give a distortion-free condition, Improvement of the composite second-order (CSO) distortion, which results from the cancellation of the laser distortion and the gain tilt induced distortion, was confirmed for VHF multichannel transmission. Furthermore, CSO distortion-free transmission in cascaded EDFA's has been demonstrated for a 42-channel AM-SCM signal by experimentally determining the optimum operating condition of the EDFA such that each amplifier generates no additive distortion     

Second-order harmonic distortion and optimal fiber length in erbium-doped fiber amplifiers

The gain of an erbium-doped fiber amplifier (EDFA) operating in the kHz regimes and its second-order harmonic distortion (SBD) are studied. Using the rate and beam-propagation equations, we have shown the dependences of the distortion on the pump power, the modulation frequency, and the position along the fiber. Moreover, it is found that the SHD is the smallest when the fiber has an optimal length for the maximum gain. A relation between the optimal length and fiber parameters is presented for calculating easily the optimal fiber length in an EDFA.     

980 nm 和1480 nm 抽运下铋基EDFA放大特性的比较研究

The population rate and power propagation equations are presented and solved to compare the amplification performances of bismuth-based Er3+-doped fiber amplifier (EDFA) pumped by 980-and 1480-nm lasers,respectively.In both single signal and coarse wavelength-division-multiplexing(CWDM)signals inputs,the 1480-nm pumped bismuth-based EDFA provides a larger signal gain than the 980-nm pumped one does,whereas the latter provides a relatively lower noise figure (NF).Comparative results indicate that the 1480-nm pumping scheme is more advantageous for bismuth-based EDFA regarding the band width and gain property.     

1.48μm泵浦的EDFA理论模型的修正与数值解

本文所建立的ＥＤＦＡ的理论模型考虑了ＡＳＥ和光纤的本征衰耗，修改了速率方程和传输方程，对泵浦光功率，信号光功率沿光纤长度的分布及ＥＤＦＡ增益特性等进行了数值解，所得结果与实验结果符合较好。     

Enhancement of fluorescence emission and signal gain at 1.53 µm in Er3+/Ce3+ co-doped tellurite glass fiber

Er3+/Ce3+ co-doped tellurite glasses with composition of TeO2-GeO2-Li2O-Nb2O5 were prepared using conventional melt-quenching technique for potential applications in Er3+-doped fiber amplifier (EDFA). The absorption spectra, up-conversion spectra and 1.53 µm band fluorescence spectra of glass samples were measured. It is shown that the 1.53 µm band fluorescence emission intensity of Er3+-doped tellurite glass fiber is improved obviously with the introduction of an appropriate amount of Ce3+, which is attributed to the energy transfer (ET) from Er3+ to Ce3+. Meanwhile, the 1.53 µm band optical signal amplification is simulated based on the rate and power propagation equations, and an increment in signal gain of about 2.4 dB at 1 532 nm in the Er3+/Ce3+ co-doped tellurite glass fiber is found. The maximum signal gain reaches 29.3 dB on a 50 cm-long fiber pumped at 980 nm with power of 100 mW. The results indicate that the prepared Er3+/Ce3+ co-doped tellurite glass is a good gain medium applied for 1.53 µm broadband and high-gain EDFA.     

Effects of nonlinear dispersion in EDFA's on optical communicationsystems

The signal-induced change of the refractive index in an erbium-doped fiber amplifier (EDFA) causes a phase modulation imposed on a signal when passing the EDFA. In this paper, we apply our extended EDFA model on an optical communication system. The model includes this phase modulation, by including the nonlinear dispersion in an EDFA, and the spontaneous emission noise. The influence of these effects on an optical communication system is examined by means of Q-factor and eye diagram. We assume an intensity modulated-direct detection (IM-DD) system operating at 193 THz (1552.5 nm) with a bit rate of 10 Gb/s in the anomalous dispersion regime and a total fiber length of 500 km. The fibers are assumed to be dispersion shifted ones, EDFAs are used to compensate for the fiber loss. By numerical simulation we obtain results for the influence of the phase modulation (nonlinear dispersion) due to the signal induced change of the refractive index in an EDFA and the spontaneous emission noise at different input peak powers. Neglecting the signal-induced change of the refractive index strongly underestimates the Q-factor in the anomalous dispersion regime. Therefore it should be included for reliable system simulations. This can be done with the numerical model presented here     

ASE Analysis and Correction for EDFA Automatic Control

A theoretical model is described that can be used for calculating the amplified spontaneous emission (ASE) at the output of an optical amplifier. The technique can be used to determine the usable optical signal power at the output of an erbium-doped fiber amplifier (EDFA) operating in the constant-output-power control mode. The model was experimentally verified by automating an EDFA to operate in the constant-signal-power control mode using an ASE correction based on our model. Calculated signal-output powers were then compared to the measured values that were obtained using an optical spectrum analyzer.     

High-gain coefficient long-wavelength-band erbium-doped fiberamplifier using 1530-nm band pump

A 1530-nm band has been studied as a pump wavelength for the long-wavelength-band erbium-doped fiber amplifier (L-band EDFA). The pump source is built using a tunable light source and cascaded conventional-band (C-band) EDFA. The L-band EDFA uses a forward pumping scheme. Within the 1530-nm band, the 1545-nm pump demonstrates 0.45-dB/mW gain coefficient, which is twice better than that of conventional 1480-nm pumped EDFA. The noise figure of the 1530-nm pump is at worst 6.36 dB, which is 0.75 dB higher than that of the 1480-nm pumped EDFA. Such high-gain coefficient indicates that the L-band EDFA consumes low power     

Gain flattening of an erbium-doped fiber amplifier using ahigh-birefringence fiber loop mirror

We propose a flexible method for flattening the gain profile of an erbium-doped fiber amplifier (EDFA). The method is based on a high-birefringence fiber loop mirror (HiBi-FLM), which contains a number of high-birefringence fiber sections and polarization controllers. We show that, by setting the polarization controllers properly, the reflection spectrum of the loop mirror can be adjusted to compensate for the variations in the gain profile of the EDFA. The method is demonstrated experimentally by using a single-section HiBi-FLM and a two-section HiBi-FLM, respectively, With a two-section HiBi-FLM, we are able to flatten the gain profile of an EDFA to within ±0.9 dB over a bandwidth of 33 nm at the center wavelength of 1543 nm, under different operating conditions of the EDFA