S波段光纤放大器的研究

文章介绍了掺铥光纤放大器(TDFA)和增益位移掺铥光纤放大器(GS-TDFA)的基本工作原理.分析了不同的泵浦波长选择.随后,作者提出了一种使用半导体激光器泵浦两级高掺杂掺铥光纤的增益位移放大器方案.采用此方案的光纤放大器在30 nm工作带宽上光增益大于20 dB,饱和输出功率大于17 dBm,噪声指数为5.9～6.2 dB.     

S—波段光纤放大器及其研究进展

介绍了实现S-波段放大的3种光纤放大器；掺铥光纤放大器（TDFA）、增益位移TDFA（GSTD-FA）和光纤喇曼放大器，就其原理、结构、特点和发展现状进行了综述。     

S波段TDFA泵浦方式的比较

随着光纤通信技术的发展,对于S波段(1 450～1 520 nm)光放大的需求日渐升高,而Tm+3的能级结构中存在满足S波段光放大的能级跃迁,因此掺铥光纤放大器(TDFA)是S波段最具潜力的激光放大器件,对于光纤通信系统的通信窗口向S波段拓展具有十分重要的意义和价值.由于Tm+3的能级结构非常丰富并且拥有自身的特点,因此TDFA的泵浦波长有着众多的选择,其中一些泵浦方式拥有巨大的商业实用价值.     

TDFA最新研究进展

掺铥光纤放大器（TDFA）在石英光纤的低损耗S波段（1450－1510nm）对信号进行有效的放大，目前已成为通信领域内竞相开发的一种新型光 纤放大器，本文首先简单介绍了其研究历程，然后综述了其最亲研究进展及应用情况。     

基于FBG铥钬共掺光纤放大器反向ASE的再利用

针对铥钬共掺光纤放大器在放大2μm以上长波段信号光时因存在反向放大的自发辐射(ASE)而造成的放大效率浪费的问题,提出了在放大器输入端插入一个中心波长为1950nm的光纤光栅(FBG)的方案,并从理论上研究了光栅参数对放大器在2μm以上波段增益特性的影响。通过数值模拟给出了几种不同的铥钬掺杂比例下、有无FBG时,放大器对2040nm信号光的增益随光纤长度的变化曲线,分析了插入FBG后放大器最大增益和对应的最佳光纤长度的变化,以及这种变化对铥钬掺杂比例的依赖性。通过模拟放大器输入端的反向ASE光谱,以及抽运光、信号光、ASE与FBG反射光功率沿光纤传输的演化行为,解释了FBG对放大器产生影响的根本原因,并进一步指出为提高放大器长波段增益而加入短波段FBG的适用条件。并初步研究了加入FBG对放大器增益谱及噪声特性的影响。     

掺铥光纤放大器及其研究进展

介绍了S-波段光纤放大器——掺铥光纤放大器和增益位移掺铥光纤放大器的原理、结构、发展现状。     

S-band光纤放大器的研究进展

主要介绍了几种S-band光纤放大器,包括光纤喇曼放大器(RFA)、增益位移掺铥光纤放大器(GS-TDFA)、掺铒光纤放大器(EDFA)和光学参量光纤放大器(OPA),综述了其原理、特点、研究现状及发展趋势。     

基于增益开关技术的全光纤结构纳秒脉冲掺铥光纤激光器

工作在2μm波段的脉冲掺铥光纤激光器,可望在遥感探测、相干雷达、空间光通信、激光医疗和特种材料加工等领域获得重要应用。目前,利用波长在1.55μm附近的脉冲掺铒光纤激光器作泵浦源的增益开关掺铥光纤激光器是实现全光纤结构纳秒脉冲掺铥光纤激光器的理想方式之一。采用实验研发的纳秒脉冲掺铒激光器作种子源,研制了全光纤MOPA(masteroscillator power amplifier)结构的纳秒脉冲掺铒光纤激光器,输出波长1 547 nm,脉冲频率100 kHz,脉冲宽度50 ns,平均功率1 W,单脉冲能量10μJ。使用该脉冲掺铒光纤激光器抽运掺铥光纤,实现了波长1 963 nm的增益开关脉冲激光输出。该掺铥光纤激光器为全光纤结构,重复频率100 kHz,最小脉宽47 ns,最大单脉冲能量100 nJ。激光输出稳定可靠,更高的单脉冲能量,平均功率和峰值功率可由进一步级联光纤放大器实现。     

在0.8μm带泵浦的掺铥—钬ZBLYAN光纤放大器1.4μm带增益特性

日本ＮＴＴ光电子实验工厂的Ｔ．Ｓａｋａｍｏｔｏ等人在本文中叙述了１．４μｍ带掺铥钬ＺＢＬＹＡＮ光纤放大器的增益特性，对于７３．５ｍＷ的泵浦功率级，在整个１．４μｍ带可获得信号增益，对于０．７９μｍ下１５０ｍＷ的泵浦功能，在１．４６μｍ信号波长下获得了１８ｄＢ的最大信号增益，在１．４５～１．５０μｍ信号波长区，噪声系数为５．６ｄＢ，由掺铥－钬的ＺＢＬＹＡＮ光纤和掺铥ＺＢＬＹＡＮ光纤增益性能的比较，进     

瓦级输出全光纤结构2.0μm掺铥皮秒脉冲光纤激光器

研制了高功率全光纤结构2μm波段掺铥皮秒脉冲光纤激光器。该激光器采用了主振荡功率放大(MOPA)结构设计,种子源采用790nm的多模半导体激光器作为抽运源、双包层掺铥光纤作为激光增益介质、半导体可饱和吸收镜(SESAM)作为锁模器件,从而实现了重复频率为10.4MHz的皮秒激光脉冲输出,其最大平均输出功率为15mW。种子源经过一级掺铥光纤放大器后,获得了1.1W高平均功率输出,相应的单脉冲能量高达105nJ,激光脉冲宽度为9ps,峰值功率为11.6kW。此时测得激光脉冲的中心波长为1963nm,3dB光谱带宽为0.5nm。     

Study on the gain excursion and tilt compensation for 1.4- and1.5-μm dual wavelength pumped TDFA

We analyze the gain excursion and tilt function of the thulium doped fiber amplifiers (TDFAs) for the 1.4- and 1.5-μm dual-wavelength pump approach. We also reveal that those two pump wavelengths act as independent control. factors for gain level and tilt function, because each pumps influence the populations of the first and second excited states (³H₄-³F₄ ) in a different manner. Gain excursion and gain tilt control of the TDFAs under the channel add-drop situations are demonstrated, revealing a suitable approach and inner dynamics of the gain/tilt excursion and compensation mechanisms for TDFAs     

Transient gain behavior in 1050/1550-nm dual-wavelength pumped TDFAs

We present an experimental study on transient events in 1050/1550-nm dual-wavelength pumped thulium-doped fiber amplifiers (TDFAs)-a promising candidate for S-band telecommunication applications. For appropriate power ratios of the two pump wavelengths, transient excursions due to signal add-drop are comparable to those in single-wavelength pumped TDFAs. Pump modulation effects, however, more severely impact the signal gain. With our experimental results, it should be possible to develop transient gain suppression control loops for this TDFA type.     

Gain dynamics of 14xx-nm-pumped thulium-doped fiber amplifier

Upconversion pumping in the 14xx-nm range gives the thulium-doped fiber amplifier (TDFA) a 3-dB dynamic range of 15 dB, and transient power excursion much lower than the conventional erbium-doped fiber amplifier during dynamic wavelength add-drop, due to the energy transitions inherent to the Tm/sup 3+/ ion. For specific pumping scheme and operating conditions, gain increases with increasing signal input, a behavior significantly different from conventionally optical amplifiers. This phenomenon is studied experimentally and theoretically, and promises to provide insight for gain control algorithms for TDFAs under bursty traffic conditions in a metropolitan area network environment.     

800/1060 nm dual-wavelength pumped TDFA using single active pump source

Novel 800/1060 nm dual-wavelength pumping sources for Tm/sup 3+/-doped fibre amplifiers (TDFAs) are reported: a Nd/sup 3+/-doped silica fibre laser or a Nd/sup 3+/-doped microstructured silica fibre laser, both pumped near 800 nm and emitting near 1060 nm, providing the two required TDFA pump wavelengths. A new regime of pump power ratios is explored, in which the 800 nm power is comparable to the 1060 nm power. Gain and noise figure are comparable with those obtained using individual pump modules at the two wavelengths.     

Gain-shifted thulium-doped fibre amplifiers employing novel highconcentration doping technique

A novel high thulium concentration doping technique is proposed for shifting the gain band in thulium-doped fibre amplifiers (TDFAs). The gain peak shifts from 1473 to 1505 nm when the Tm³⁺ concentration is increased from 2000 to 8000 ppm. The authors have achieved gains of >18 dB and a noise figure (NF) of <7 dB from 1480 to 1510 nm (30 nm bandwidth) for a total pump power of 500 mW     

Hybrid fiber amplifiers consisting of cascaded TDFA and EDFA for WDM signals

The detailed gain characteristics of hybrid fiber amplifiers that consist of cascaded thulium-doped fiber amplifiers (TDFAs) and erbium-doped fiber amplifiers (EDFAs) are reported. The experimental results showed that the hybrid amplifiers have gains of over 20 dB with the bandwidth of more than 80 nm in the wavelength range between 1460 and 1560 nm. The low noise figure (NF) below 7 dB was obtained in 1460-1540 nm when placing a TDFA in the first stage followed by an EDFA and in 1480-1560 nm when placing amplifiers in a reversed order. The gain of TDFA and EDFA was optimized for minimizing the gain variation ratio (GVR=(maximumgain-minimumgain)/minimumgain: in the unit of decibels) of the hybrid amplifiers, and it could be minimized to less than 0.4 for the amplifiers that have gain in the wavelength region from 1460 to 1537 nm. The gain-equalization technique was applied, and the hybrid amplifier that had an average gain of 20 dB, a gain excursion of less than 2 dB, an output power of 14.5 dBm, and an NF of less than 7 dB in the 77-nm gain band was achieved.     

Novel Gain Spectrum Control Method Employing Gain Clamping and Pump Power Adjustment in Thulium-Doped Fiber Amplifier

In this paper, we propose a novel method for controlling the gain spectrum of a thulium-doped fiber amplifier (TDFA) in the S-band. The conventional gain spectrum control method used for a silica erbium-doped fiber amplifier (EDFA) cannot be applied to TDFAs because of the complicated fluctuation of the TDFA gain spectrum. Our proposed method controls the gain spectrum by a combination of gain clamping and pump power adjustment. The algorithm for the method is as simple as that for the conventional EDFA gain spectrum control method. Furthermore, we describe a function for correcting the gain excursion generated by the incorporation of amplified spontaneous emission (ASE) at a signal monitoring photodiode (PD). We achieved a gain excursion of 0.35 dB against a total input signal power of 32 to 2 dBm.     

利用普通熔融拉锥机实现光子晶体光纤拉锥

光子晶体光纤的拉锥是实现光子晶体光纤潜在应用价值的重要技术手段。通过优化普通光纤拉锥机的参数,利用"快速低温"拉锥法有效控制了光子晶体光纤空气孔的相对塌缩。实验中实现了两种不同光子晶体光纤的拉锥,光纤外径分别从原来的125μm拉锥到50μm和30μm,光纤的孔直径和孔间距之比基本保持不变,拉锥损耗小于0.4 dB。基于普通熔融拉锥机的光子晶体光纤低损耗拉锥为光纤器件的制作奠定了基础。     

LPFG包层模对环境折射率的灵敏度分析

从理论和实验两个方面分析了长周期光纤光栅（LPFG）前3阶包层模的透射谱特性与光栅外包层厚度间的关系。LPFG的谐振波长漂移范围随着其外包层厚度的减小而扩大,同时,高阶耦合模LP04模的谐振波长漂移强于低阶模。研究表明,通过设计光纤光栅结构能改善其各阶包层模谐振峰对环境折射率的灵敏度。     

渐变折射率聚合物光纤的研究进展

介绍ＧＩＰＯＦ的带宽特性和应用,对比了ＳＩＰＯＦ、铜系电缆、玻璃系光纤和ＧＥＰＯＦ的传输特性,着重分析了ＧＩ ＰＯＦ的三种制备方法：普通共取法 面凝胶法和等离子态法,并综述了ＧＩ ＰＯＦ的研究的最新进展,指出了国内外ＧＩ ＰＯＦ的差距。