Low noise gain-clamped L-band erbium-doped fiber amplifier by utilizing fiber Bragg grating

A novel gain-clamped long wavelength band (L-band) erbium-doped fiber amplifier (EDFA) is proposedand experimented by using a fiber Bragg grating (FBG) at the input end of the amplifier. This designprovides a good gain clamping and decreases noise effectively. It uses two sections of erbium-doped fiber(EDF) pumped by a 1480-nm laser diode (LD) for higher efficiency and lower noise figure (NF). The gainis clamped at 23 dB with a variation of 0.5 dB from input signal power of -30 to -8 dBm for 1589 nm andNF below 5 dB is obtained. At the longer wavelength in L-band higher gain is also obtained and the gainis clamped at 16 dB for 1614 nm effectively. Because the FBG injects a portion of backward amplifiedspontaneous emission (ASE) back into the system, the gain enhances 5 dB with inputting small signal.     

Low noise double pass L-band erbium-doped fiber amplifier

A new double pass long wavelength band erbium-doped fiber amplifier with enhanced noise figure characteristics is demonstrated. The noise figure is improved by about 2.6 dB with the incorporation of broadband conventional-band fiber Bragg grating (FBG) in between the two segments of erbium-doped fiber. By incorporating both the pre-amplifier and the FBG, the noise figure is further improved, which varies from 4.0 to 5.0 dB in the flat gain region from 1570 to 1600 nm. The gain varies from 32.0 to 33.4 dB within this region. The new amplifier with high gain and low noise figure can be useful as an inline amplifier in a wavelength division multiplexing transmission system.     

Improvement of gain and noise figure by periodic bending of an erbium-doped fiber

The gain and noise figure can be improved by periodic bending of an erbium-doped fiber. Bending of 5.4 m at the beginning of an erbium-doped fiber results in a reduction of noise figure, a gain increment, and a reduction of forward amplified spontaneous emission of 5.1, 3.6, and 1.5 dB for a 1533-nm small signal; 4.0, 1.9, and 2.1 dB for a 1550-nm small signal; and 2.7, 0.9, and 1.8 dB for a 1560-nm small signal (-40 dBm), respectively. In addition, the periodic bending can operate an erbium-doped fiber amplifier at quantum-limited noise and enables its operation to be more stable.     

基于环形芯光纤的超低差分模式增益涡旋光纤放大器

提出了一种基于环形芯铒离子部分掺杂光纤的涡旋光纤放大器。针对该掺铒光纤的放大特性,研究了光纤长度、掺铒浓度与抽运功率对信号模式增益特性的影响。研究结果表明,该光纤放大器能够支持22个轨道角动量模式稳定传输,且C波段(1530~1565 nm)所有信号模式增益大于23 dB,信噪比高于27 dB,差分模式增益小于0.015 dB。所提出的基于环形芯光纤的涡旋光纤放大器具有支持轨道角动量模式数量多、差分模式增益低、信噪比高的优势,对于OAM复用长距离传输系统中的在线放大具有重要参考价值。     

All-fiber few-mode erbium-doped fiber amplifier supporting six spatial modes

Using the few-mode erbium-doped fiber(FM-EDF) with a simple two-layer erbium-doped structure, we demonstrate an all-fiber FM-EDF amplifier. The gain equalization among the six spatial modes supported by the FM-EDF is achieved when only the pump in the fundamental mode(LP_(01)) is applied. When the signals in six spatial modes are simultaneously amplified, the average modal gain is about 15 dB, and differential modal gain is about 2.5 dB for the signal at 1550 nm.     

Gain Efficient L-band EDFA With Dynamic Gain Equalization

A gain efficient L-band erbium-doped fiber amplifier with dynamic gain equalization is presented. Using a single fiber Bragg grating and a static equalizer, the gain is clamped at 27dB with less than 0.5dB variations over 35nm.     

Optimization of gain flattened C-band EDFA using macro-bending

Optimization of gain flattened C-band erbium-doped fiber amplifier (EDFA) using a macrobending method with an improved gain flatness and bandwidth is demonstrated. The optimization for gain flatness and bandwidth was achieved by varying the bending radius and the length of the doped fiber. In the optimized condition, the gain saturation effect as well as the energy transfer from shorter wavelengths to longer wavelengths resulted in a flattened and broadened gain profile in the C-band region. The amplifier was optimized to a 9 m long erbium-doped fiber (EDF) with erbium ion concentration of 1100 ppm and bending radius of 6.5 mm. The gain variation of the EDFA is obtained within ±1 dB over 25 nm bandwidth of C-band region.     

Simultaneously gain-flattened and gain-clamped erbium fiber amplifier

In this paper, we propose and demonstrate a simple erbium amplifier module based on an erbium-doped fiber amplifier (EDFA) and an erbium-doped waveguide amplifier (EDWA) in serial, having gain-flatted (GF) and gain-clamped (GC) functions simultaneously. In first proposed GF amplifier scheme, the maximum gain variation of 2.5 dB can be observed in the effective range of 1528 to 1562 nm and the entire gains are above 35 dB with the input signal power of ?30 dBm. Hence, we investigate second scheme by optical feedback method in the proposed fiber amplifier achieving gain-flattened (GF) and gain-clamped (GC) efficiencies simultaneously. Thus, the maximum gain variations of ±0.8 and ±1.8 dB can be obtained in the operating range of 1530 to 1564 nm, when the input signal powers are ?16 and ?40 dBm, respectively. Moreover, the dynamic gain profile can be adjusted and dynamic input power range is also measured based on the proposed GF and GC fiber amplifier.     

基于长周期光纤光栅滤波器的掺铒光纤放大器理论和实验研究

从理论和实验上研究了带有高频二氧化碳激光写入的低成本长周期光纤光栅（LPFG）掺铒光纤放大器（EDFA）.结果表明,单波长和多波长EDFA的性能都可以通过在掺铒光纤（EDF）中插入长周期光纤光栅用作自发辐射噪声（ASE）滤波器或增益平坦器来提高性能.优化设计了带LPFG噪声滤波器的线放EDFA,与没有LPFG噪声滤波器相比,线放的噪声和小信号增益分别被减小和提高了约0.5 dB和7 dB。通过在多波长EDFA的EDF中插入一个LPFG增益平坦滤波器的方法,获得了1.5 dB的增益平坦度,与没有LPFG平坦器相比,EDFA的噪声被减小了0.1 dB,增益被提高了1 dB.     

A hybrid high-gain double-pass erbium-doped fiber amplifier with dispersion compensation feedback loop

A new double-pass erbium-doped fiber amplifier (DP-EDFA) using chirped fiber Bragg grating (CFBG) is reported here showing a gain of 53.4 dB and noise figure (NF) of 5.36 dB. The proposed amplifier at the same time provides dispersion compensation through the use of CFBG.     

Remotely Pumped Hybrid Amplifiers for Extended Bidirectional Passive Optical Networks

In this contribution, we optimize design parameters of hybrid optical amplifiers utilizing distributed Raman amplification in transmission fiber and gain of discrete, remotely pumped erbium-doped fiber amplifier (EDFA) for wideband, bidirectional operation in metropolitan area networks (MAN). The design is based on an application of a numerical model, which takes into account pump-to-pump and signal-to-signal interactions and generation of amplified spontaneous emission in the Raman amplifier and solves the standard rate-propagation equations in an erbium-doped fiber (EDF). We predict 12 dB gain across 72 nm of optical bandwidth with gain ripple better than 10%. The recently proposed serial topology of EDFA is considered; this enables the wideband, bidirectional operation of a hybrid amplifier with only two pump laser diodes emitting in the 1430 and 1480 nm bands.     

Gain-clamping techniques in two-stage double-pass L-band EDFA

Two designs of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) for gain clamping in double-pass systems are demonstrated and compared. The first design is based on ring laser technique where a backward amplified spontaneous emission (ASE) from the second stage is routed into the feedback loop to create an oscillating laser for gain clamping. The gain is clamped at 18.6 d B from -40 to -80 dBm with a gain variation of less than ±0.1 dB and a noise figure of less than 6 dB. Another scheme is based on partial reflection of ASE into the EDFA, which is demonstrated using a narrowband fiber Bragg grating. This scheme achieves a good gain clamping characteristic up to -12 dBm of input signal power with a gain variation of less than ±0.3 dB from a clamped gain of 22 dB. The noise figure of a 1580 nm signal is maintained below 5 dB in this amplifier since this scheme is not based on lasing mechanism. The latter scheme is also expected to be free from the relaxation oscillation problem.     

Gain-clamping in two-stage L-band EDFA using an unwanted backward ase from second stage

A gain clamping technique for the long wavelength band erbium-doped fiber amplifier (L-band EDFA) is presented. It uses two circulators and a broad band fiber Bragg grating to route wasted backward C-band ASE from the second stage and launch it back into the input end of the first stage of a two-stage amplifier. The two-stage L-band EDFA has shown a small signal gain improvement of 5.7 dB compared to a single-stage amplifier with a slight noise figure degradation. By utilizing the wasted backward ASE, a L-band gain-clamped EDFA with high gain can be realized. Compared to the unclamped case, this gain-clamping technique is effective in reducing the total gain variation as small as 0.3 dB.     

Effect of Cascading Amplification Stages on the Performance of Serial Hybrid Fiber Amplifier

Abstract

This study demonstrates simulation and experimental validation of a wideband serial hybrid Raman/erbium-doped fiber amplifier. Two configurations are adopted; in type A, a Raman amplifier is the first stage, and in type B, an erbium-doped fiber amplifier is the first stage. At low input signal power, the average gain level is 20 dB with a flat gain bandwidth of 40 nm for both configurations. The noise figure in type B is dominated by the erbium-doped fiber amplifier and produces lower values and flatter spectra than in type A. The gain of the proposed hybrid amplifiers is affected more by the second amplification stage.     

A 0．98μm Laser Diode Pumped Erbium－Doped Fiber Amplifier with 40nm Bandwidth

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掺铒光纤激光放大的研究

本文研究了描述掺铒光纤激光放大的速率方程解,分析了光纤中几种场分布和铒离子横向分布时的解析解,并进行了数值计算.得到了任意信号强度(包括大信号)时的增益以及影响信号增益的主要参数,利用532nm激光泵浦掺铒光纤,得到信号的最大增益为29.5dB.     

Effect of injection of C-band ASE on L-band erbium-doped fiber amplifier

The effect of injecting conventional band (C-band) amplified spontaneous emission on the performance of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated. It uses a circulator and broadband fiber Bragg grating (FBG) to route C-band ASE from a C-band EDFA. Injection of a small amount of ASE (attenuation of 20 dB or above) improves the small signal gain with a negligible noise figure penalty compared to that of an amplifier without the ASE injection. A maximum gain improvement of 3.5 dB is obtained at an attenuation of 20 dB. At very large amounts of ASE injection (attenuation of 0 dB), the gain of the amplifier is clamped at 15.2 dB from ?40 to ?10 dBm with a gain variation of less than 0.3 dB. The saturation power is also increased from ?8 dBm (for without ASE injection) to 2 dBm (VOA=0 dB) with a slight noise figure penalty. These results show that the ASE injection technique can be used either for gain improvement or for gain clamping in L-band EDFA.     

Bismuth-based erbium-doped fiber as a gain medium for L-band amplification and Brillouin fiber laser

Bismuth-based erbium-doped fiber (Bi-EDF) is demonstrated as an alternative medium for optical amplification and nonlinear applications. The bismuth glass host provides the opportunity to be doped heavily with erbium ions to allow a compact optical amplifier design. The bismuth-based erbium-doped fiber amplifier (Bi-EDFA) is demonstrated to operate at wavelength region from 1570 to 1620 nm using only a 215 cm long of gain medium. The maximum gain of 15.8 dB is obtained at signal wavelength of 1610 nm with the corresponding noise figure of about 6.3 dB. A multi-wavelength laser comb is also demonstrated using a stimulated Brillouin scattering in the 215 cm long Bi-EDF assisted by the 1480 nm pumping. The laser generates more than 40 lines of optical comb with a line spacing of approximately 0.08 at 1612.5 nm region using 152 mW of 1480 nm pump power.     

长波段掺铒光纤放大器用掺铒光纤的设计考虑

本文分析了长波段掺铒光纤放大器(EDFA)的增益系数与Er³⁺离子浓度的关系.研制了铝共掺杂的高浓度掺铒光纤,以缩短长波段掺铒光纤的长度.用两级泵浦实现了L-波段EDFA.光纤放大器的掺铒光纤总长18m,在1570nm波长处的小信号增益为42.26dB,输出功率为17.5dBm.我们认为,较低的浓度淬灭效应归因于光纤中较高的A1掺杂浓度.当总的输入信号功率为-3dBm时,在1570至1600nm间的7路WDM信号的增益不平坦度仅为0.68dB..     

一种基于新型长周期光纤光栅的动态增益均衡器

报道了一种用高频CO²激光脉冲写出的长周期光纤光栅的温度特性和弯曲特性.实验表明,这种长周期光纤光栅的波长漂移随温度的变化呈线性关系,它的透射峰幅值变化随弯曲量的变化也呈线性关系.基于这两种线性关系,通过控制新型长周期光纤光栅的谐振峰位置和幅度,动态平坦了一组掺铒光纤放大器增益谱线.实验结果表明在C波段32nm范围内掺铒光纤放大器增益谱线平坦度可动态调整为±0.7dB.