S+C bands amplification in a distributed Er-doped Raman fiber

A novel hybrid optical amplifier covering entire S- and C-bands has been proposed. A silica fiber configured with an erbium (Er)-doped cladding and a germanium-doped core was used. Amplification was achieved by stimulated Raman scattering along with the Er ions' radiative transition in a fiber. A numerical simulation has been performed to analyze the amplification characteristics. Fiber parameters such as optical loss, Er concentration, fiber length, and pump power were taken into consideration to calculate the optimum pump power and fiber length for a flat gain characteristic over the entire S- and C-bands.     

Concentration effect on optical amplification characteristics ofEr-doped silica single-mode fibers

Optical amplification characteristics for Er-doped silica core single-mode fiber amplifiers with different Er concentrations pumped by 1.48-μm-wavelength laser diodes are studied. Optical gain drastically depends on Er concentration, even when the Er concentration is less than 1000 p.p.m. In the case of the 40-mW incident pump power, the maximum net gain for the fiber containing 77 p.p.m. Er is higher than that for the fiber containing 970 p.p.m. Er by 11.4 dB     

A low-noise and gain-flattened amplifier composed of a silica-based and a fluoride-based Er/sup 3+/-doped fiber amplifier in a cascade configuration

We propose a novel low noise and gain-flattened Er/sup 3+/-doped fiber amplifier (EDFA) with a cascade configuration for wavelength division multiplexing (WDM) signals. In this configuration, a 1480-nm pumped fluoride-based EDFA is joined to a 980-nm pumped silica-based EDFA through an optical isolator. By adjusting the silica-based Er/sup 3+/-doped fiber length in the silica-based EDFA, we realized an excellent flat gain EDFA with a gain excursion of less than 0.9 dB and noise figure of 5.7/spl plusmn/0.2 dB, and a low noise EDFA with a noise figure of 5/spl plusmn/0.2 dB and a gain excursion of less than 1.4 dB, for 8 channel WDM signal in the 1532-1560-nm wavelength region.     

碲基掺铒光纤放大器增益均衡的数值模拟

针对宽带碲基掺铒光纤放大器(EDTFA)本征增益谱不平坦特性,研究了采用双级串连结构,并在两段光纤中间加入增益均衡滤波器来实现增益平坦.模拟结果显示,通过设计一定结构的滤波谱,在37信道同时输入的情况下,铒离子掺杂浓度为4000 ppm时,使1536～1608 nm范围带宽内的增益达到了24 dB左右,噪声指数小于5.5 dB,增益谱的不平坦度小于1 dB;铒离子掺杂浓度为6000 ppm时,使1536～1608 nm范围带宽内的增益达到了23.5 dB左右.噪声指数小于5 dB,增益谱的不平坦度小于1dB.优化后的级连EDTFA可以满足WDM系统的要求.     

Fluoride-based erbium-doped fiber amplifier with inherently flat gain spectrum

We successfully developed a fluoride-based Er/sup 3+/-doped fiber amplifier (F-EDFA). An average signal gain of 26 dB was achieved for 8 channel wavelength division multiplexed (WDM) signals in the 1532-1560 nm wavelength region with a gain excursion of less than 1.5 dB at an input signal power of -20 dBm per channel. Furthermore, we studied the amplification characteristics of the F-EDFA for WDM signals. The following experimental results were obtained. (1) For an 8-channel WDM signal in the 1532 to 1560 nm wavelength region, the gain excursion between channels can be suppressed to within 1.5 dB. However, the wavelength region allowing a gain excursion of 1.5 dB, is between 1536-1560 nm for the silica-based Er/sup 3+/-doped fiber amplifier. (2) F-EDFAs have a flat gain region between 1534-1542 nm. The gain excursion of this region is less than 0.2 dB for WDM signals.     

Wideband Hybrid Fiber Amplifier Using Er‐Doped Fiber and Raman Medium

In this paper, we report the experimental results of a hybrid wideband fiber amplifier. The amplifying medium is a concatenated hybrid fiber consisting of Er‐doped fiber (EDF) and dispersion compensating fiber (DCF). The gain mechanisms are based on stimulated emission in the EDF and stimulated Raman scattering (SRS) in the DCF. Since we simultaneously use optical amplification by the two processes, the gain bandwidth is easily expanded over 105 nm by a two‐tone pumping scheme. Using an experimental setup constructed with a hybrid structure of EDF‐DCF‐EDF, we analyzed the spectral behavior of amplified spontaneous emission for pumping powers. We achieved an optical gain of over 20 dB in the wavelength range from 1,500 to 1,600 nm under optimized pumping conditions to make the spectral gain shape flat.     

Er-La共掺杂光纤特性的研究

采用纤芯Er、La及Al共掺的方法,制备了高掺杂浓度的Er-La共掺光纤(ELDF),其吸收谱和发射谱比常规Er-Al光纤都有明显的展宽。测试其在C-波段超短长度实现了9．0dB／m的增益,NF小于5dB;L-波段输出功率大于17．5dBm,NF小于5．5。ELDF放大器(ELDFA)产生的四波混频(FWM)等非线性效应比常规掺Er光纤放大器(EDFA)有较大改善,实现高输出功率,低NF和低非线性。     

Optimum parameter design of Er/sup 3+/-doped fiber for optical amplifiers

The parameters of Er/sup 3+/-doped fiber which optimize the signal gain of a fiber amplifier pumped by a 1.48- mu m laser diode are theoretically determined using the rate equation for a three-level laser system. The basic parameters specified are the relative-index difference and the cutoff wavelength. The optimum cutoff wavelength of a completely Er/sup 3+/-doped core fiber with a step-index profile is 0.8 mu m regardless of the value of the relative-index difference. The optimum cutoff wavelength depends on the Er/sup 3+/-doped area radius.<>     

被动锁模掺Er3+氟化物光纤激光器理论研究

根据非线性薛定谔方程建立了基于可饱和吸收体被动锁模掺Er3+氟化物光纤激光器的理论模型,研究了中红外超短脉冲在掺Er3+氟化物光纤激光器中形成的物理机制,数值模拟了被动锁模掺Er3+氟化物光纤激光器中中红外超短脉冲的演化过程,重点分析了掺Er3+增益光纤长度,可饱和吸收体不饱和损耗对被动锁模掺Er3+氟化物光纤激光器产生中红外超短脉冲的影响,并给出了参数设置范围。研究发现:当小信号增益系数、可饱和吸收体不饱和损耗、腔内净色散量为一定值,掺Er3+氟化物光纤长度在一定范围时,才会出现稳定的锁模脉冲,且随着掺Er3+氟化物光纤长度增加脉冲宽度变窄、光谱变宽、峰值功率增高;当掺Er3+氟化物光纤长度、腔内净色散量、小信号增益系数为一定值时,可饱和吸收体不饱和损耗在一定的范围时可以得到稳定的锁模脉冲,且随着可饱和吸收体不饱和损耗的增加脉冲宽度变窄,光谱先变宽后变窄变化范围不大,峰值功率增加。     

41-nm 3-dB gain-band optical amplifier using an Er-doped core andSm-doped inner-cladding fiber without external filters

A new fiber structure optical fiber amplifier was reported where the core was doped with erbium (Er) and the inner-cladding was doped with samarium (Sm). Feasibility of gain control by evanescent wave interaction with an absorbing material in the inner-cladding was experimentally demonstrated. The optical amplifier using the proposed fiber resulted in the gain variation between gain peak and valley less than 2.5 dB without using external gain equalizing filters     

Performance of a high concentration Er/sup 3+/-doped alumino silicate fiber amplifier

We report the gain, noise figure, output saturation power, and conversion efficiency of a highly concentrated Er/sup 3+/-doped alumino silicate fiber amplifier. We obtain a gain per unit length of 1.0 dB/cm, which corresponds to the highest gain per unit length obtained in an Er/sup 3+/-doped fiber amplifier. The pump power threshold ranges from 2 to 5 mW, depending on the fiber length.     

铒铥共掺碲基质宽带光纤放大器研究

文章作者分析了铒铥共掺碲基质光纤放大器在980 nm泵浦下Er~(3+)-Tm~(3+)离子之间的能量转移过程,建立了速率方程和功率传输方程,并通过仿真得出了其放大增益随光纤长度和泵浦功率的变化规律.仿真结果表明:通过优化光纤长度和泵浦功率,该放大器可以在1 440～1 540 nm波段得到高达50 dB的平坦增益.     

OPCI系统不同掺杂截面EYDFA增益瞬态的比较

为了研究分组与线路集成系统中突发模式大功率Er/Yb共掺光纤放大器(EYDFA)的瞬态性能,在函数极限的基础上采用迭代算法,建立了基于非线性方程速率方程的、不同掺杂截面EYDFA增益瞬态的比较模型,分析比较了有/无反馈条件下,不同掺杂截面的光分组(OPS)和光线路交换(OCS)输出信号的增益瞬态.结果表明,无反馈条件下,纤芯直径为4.6m的EYDFA,其OPS和OCS输出信号功率漂移小于纤芯直径为3.6m的EYDFA,功率漂移的改善约为12%;带反馈条件下,增大掺杂光纤直径,弛豫振荡导致的EYDFA增益抖动随之减小.故增大掺杂光纤直径,能有效抑制EYDFA反馈环路的弛豫振荡.     

Recent Advances in New Band Rare-earth Doped Fiber Amplifiers

Broadband, high bit rate, long hauls and system intelligence are current trends in developing fiber optic communication systems. The ever-increasing traffic demands have made it urgent to develop new band optical fiber amplifier. Laser characteristics of various rare-earth ion including Er^3 , Tm^3 , Pr^3 , Dy^3 ,Ho^3 ,and Nd^3 doped fiber are reviewed. Recent advances of rare-earth doped fiber amplifiers with wideband and flat gain are also introduced.     

Theoretical analysis of gain characteristics of Er/sup 3+/-Tm/sup 3+/-codoped tellurite fiber amplifier

The rate and power propagation equations of Er/sup 3+/ and Tm/sup 3+/-codoped tellurite fiber amplifier pumped by 800-nm laser are presented and solved to analyze the dependences of gain at both 1470 and 1530 nm on the codoping concentration of Er/sup 3+/ and Tm/sup 3+/, fiber length, and input signal power. The numerical results show that with pump power of 200 mW and fiber length of 1.5 m, the gain at both 1470 and 1530 nm may reach 12.0 dB when the codoping concentration of Er/sup 3+/ and Tm/sup 3+/ reach 4.0/spl times/10/sup 25/ ions/m/sup 3/, 3.2/spl times/10/sup 25/ ions/m/sup 3/, respectively. The fiber length and codopant concentrations are proposed to make the two channels equivalently amplified.     

窄线宽光纤激光器

为满足传感系统的需求,研制了1 550nm单频窄线宽光纤激光器,采用环形腔结构,利用976nm激光器作为泵浦源,高掺杂掺铒光纤作为增益介质,以低掺杂掺铒光纤作为饱和吸收体,得到稳定的窄线宽激光输出。泵浦功率为200mW时,得到输出功率为21mW,线宽为7.2kHz,波长稳定度为1.26pm,相对强度噪声≤-102dB/Hz1/2。     

Effect of Ce2O3 on the 1.53 μm spectroscopic properties in Er3+-doped tellurite glasses

The crown-like zinc oxide(Zn O)samples,which are composed of a hexagonal cap and a tower-like shaft,are prepared by vapor transport method.The hexagonal cap,working as a whispering gallery mode(WGM)resonant cavity,demonstrates density-dependent ultraviolet(UV)lasing emission with a broadened and squared photoluminescence(PL)profile under UV excitation at 355 nm.Theoretical analyses based on Fermi golden rule show that the broadened spectrum profile results from the special optical mode density characteristics in a WGM micro-cavity,which is in agreement with the observed results.     

基于光纤环形镜的增益平坦L波段掺铒光纤放大器优化设计

L波段掺铒光纤放大器（EDFA）的增益介质具有本征增益平坦特性，但平坦增益值低，放大器实用性差，因此对放大器优化设计提高平坦增益有十分重要的意义。使用光纤环形镜（FLM）作为增益平坦滤波器进行L波段掺铒光纤放大器的增益平坦化实验，实现了高增益值的平坦输出。     

Solid-state laser pumping of 1.5-μm optical amplifiers andsources for lightwave video transmission

An optical power amplifier and a laser source are demonstrated at 1.5 μm. A diode-pumped Nd:YAG laser is used as the pumping source for an Er/Yb co-doped gain medium. The power scaling advantages of this approach are demonstrated. Up to +21 dBm of output power is obtained from the Er/Yb amplifier and up to +19 dBm is obtained from the laser source. The Er/Yb power amplifier was deployed in a 42-channel AM link with 40 km of fiber, and an optical loss budget of 18 dBm was demonstrated     

掺铒光纤放大器增益特性及参量优化

本文以铒光纤放大器的速率方程理论分析计算了铒光纤参量与放大器增益特性的关系，首次得到了铒光纤截止波长的解析表达式。