Operation of erbium-doped fiber amplifiers and lasers pumped withfrequency-doubled Nd:YAG lasers

An optical amplifier consisting of an erbium-doped germanosilicate fiber optically pumped at 532 nm is described. Negligible excited-state absorption at 532 nm allows efficient pumping, enabling a gain of 34 dB at 1536 nm to be obtained for only 25 mW of pump power. The pulsed pump source produces negligible noise on the small signal if the pump repetition rate is above 10 kHz. Pulsed laser operation is achieved by pumping a Fabry-Perot erbium-doped fiber laser with a frequency-doubled Q-switched Nd:YAG laser. Pulses of 0.9-W peak power and 280-ns duration at 1.538-μm were obtained     

Characteristics of an erbium-doped fiber amplifier pumped by a frequency doubled diode-pumped Nd:YAG laser

The characteristics of an erbium-doped fiber amplifier pumped by a 532-nm diode-pumped Nd:YAG laser are presented. A maximum system gain of 31 dB at 591 Mb/s is obtained with a corresponding system noise of less than 0.5 dB. An amplified signal output power of greater than 10 mW was obtained, with a coupled pump power of 46 mW and a corresponding quantum efficiency of around 65%. By optimizing the erbium fiber design, higher system gains and saturation power levels are feasible. These figures, and in particular the combination of high output powers and low noise, establish the usefulness of this pump laser as a viable alternative to the semiconductor pump lasers currently under investigation at 1480 and 980 nm.<>     

超短环形腔布里渊掺铒光纤激光器

提出了一种超短环形腔布里渊掺铒光纤激光器(BEFL),腔长仅为10m。该BEFL以4m长的普通掺铒光纤(EDF)为激光增益介质,腔外布里渊抽运光和980nm抽运光的注入在掺铒光纤中,分别引入非线性布里渊增益和线性掺铒光纤放大器(EDFA)增益。实验结果表明,BEFL工作在单纵模状态,输出信噪比高(>40dB),抽运阈值低(～20mW),输出功率大(>10mW),且布里渊抽运光不仅决定BEFL的输出波长,更对其抽运阈值和出光功率有重要影响。     

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     

一种高性能环形可调谐光纤光栅激光器研究

研制了一种新型的高性能环形可调谐光纤光栅激光器。该激光器使用980nm LD作为泵浦源,使用长度为10. 8m的新型增益平坦掺铒光纤作为增益介质,采用可调谐光纤光栅滤波器进行波长调谐,调谐范围可达41nm (1528nm～1569nm) ,中心波长可精确调谐到C波段指定的ITU - T标准中心波长处, 3dB 带宽< 0. 08nm, 25dB带宽< 0. 2nm,波长稳定性优于0. 01nm,边模抑制比> 60dB。最大输出功率46. 94mW,功率稳定性优于±0. 02dB,阈值泵浦功率7. 3mW,斜率效率为39. 75%。并分析了不同腔长、不同输出耦合比对输出功率的影响。     

Tunable Fiber Laser Using a Broad-Band Fiber Mirror and a Tunable FBG as Laser-Cavity Ends

By using a broad-band fiber mirror (BFM) and a tunable fiber-Bragg-grating at either end of laser cavity, a wavelength tunable erbium-doped fiber laser is demonstrated. In a forward pump scheme using 100 mW pump power at 1480 nm, stable lasing output power of 21.14-mW measured at 1544.8 nm is obtained with a threshold pump power of 4.7 mW. A side-mode suppression ratio as high as 57.9 dB, wavelength tuning range up to 30 nm with step resolution of 0.2 nm and power variation less than plusmn1.0 dB are achieved. For a backward pump scheme, the BFM acts as a broad-band reflector both for the lasing signal and pump source. The high performance, cost-effective BFM based tunable fiber laser may play an important role in fiber optics communication and fiber sensing applications.     

A widely tunable erbium-doped fiber laser pumped at 532 nm

A tunable erbium-doped fiber laser with a very wide continuous-tuning range (1522-1567 nm) is discussed. The wide tuning range was achieved using an aluminum/erbium-doped fiber; the aluminum codoping is known to broaden the gain spectrum substantially. The tunable fiber laser has a ring laser configuration utilizing an inline tunable etalon as the tuning element. Continuous tuning over 45 nm in the spectral range of 1522-1567 nm was achieved with 80 nW of pumping at 532 nm, using the second harmonic of a Nd:YAG laser as the pump source     

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。     

Efficient pump wavelengths of erbium-doped fibre optical amplifier

By choosing pump wavelengths at which excited state absorption does not occur, efficient high gain operation of erbium-doped fibre amplifiers is possible. Practical pump wavelengths of 532 nm and 980 nm are identified as optimal, giving gains as high as 1.35 dB/mW and 2.2 dB/mW of pump at the two wavelengths, respectively.<>     

基于受激布里渊散射的可调谐多波长激光器

可调谐多波长布里渊掺铒光纤激光器将光纤中的SBS非线性放大同掺铒光纤的线性放大相结合得到室温稳定的多波长输出,具有波长间隔一致、线宽窄、功率谱相对平坦等优点。设计了一种基于光纤布拉格(FBG)反射的线性可调谐多波长布里渊掺铒光纤激光器。该线性腔激光器的一端利用光纤布拉格光栅作为反射镜,有效抑制了腔内自激模的影响,增加激光器输出波长数。布里渊泵浦信号进入布里渊增益介质之前经过掺铒光纤放大器的两次放大,降低了布里渊增益的阈值。该多波长激光器实现了1 530～1 560 nm之间30 nm可调谐范围的输出。在布里渊泵浦信号功率2 mW,980 nm泵源抽运功率60 mW情况下,1 540～1 554 nm范围内,获得了波长间隔0.088 nm的16个波长的输出。     

基于角度调谐F-P干涉仪的C波段可调谐激光器的研究

研究了基于法布里一珀罗(F-P)干涉原理的角度调谐的滤波器特性,使用自制的滤波器进行可调谐掺Er^3 光纤激光器实验。当980nm泵浦功率为30mW时获得了稳定的单纵模激光输出,输出功率约。0.65mW,线宽低于0.1m,在35．76nm波长调谐范围内功率变化不超过1dB,边模抑制比(SMSR)大于35dB;泵浦功率为46mW时获得了最大的输出功率,约为1mW。     

基于光纤环形镜的L-波段掺铒光纤放大器增益的提高

提出了一种基于光纤环形镜作为反射器的反射式L-波段掺铒光纤放大器(EDFA)结构。光纤环形镜不但可以反射后向放大自发辐射(ASE)作为二次抽运源，而且还可以反射信号，使信号得到二次放大。当抽运功率为115mW时。在1570～1605nm波长范围内，反射式L-波段掺铒光纤放大器的平坦小信号增益达到29．14dB，与前向抽运方式L-波段掺铒光纤放大器相比(保持平坦性不变)。增益提高了5．33dB。分别输入波长为1580nm和1600nm的信号，反射式L-波段掺铒光纤放大器的饱和输出功率为7．63和7．6dBm．与前向抽运方式L-波段掺铒光纤放大器相比分别提高了2．98和3dB。     

Long-wavelength erbium-doped fiber amplifier gain enhanced by ASEend-reflectors

We use for what we believe is the first time narrow-band end-reflectors to reduce losses through short-wavelength amplified stimulated emission (ASE) in silica-based erbium-doped fiber amplifiers operating at wavelengths above 1570 mm. The end-reflectors feed a small fraction of the ASE, up to a few tenths of a milliwatt, back into the amplifying fiber. The reflected ASE compresses the short-wavelength gain and thus reduces the ASE-losses, from, e,g., 50 mW for a launched pump power of 110 mW at 980 nm without end-reflector to 10 mW with an optimized end-reflector. We investigate possible improvements of gain (around 5 dB) and output power (up to 17 mW), and the influence of the amount and wavelength of the feedback     

Erbium-doped fiber amplifier pumped in the 950-1000 nm region

The pump wavelength dependence of the gain of an erbium-doped fiber amplifier pumped in the wavelength region 950-1000 nm is discussed. It is found that efficient gain at 1.557 μm, between 25 and 28 dB for 17 mW of launched pump power, can be obtained for any wavelength pump in the range 965-985 nm. The optimum length of erbium fiber needed is found to vary as a function of pump wavelength. The gain as a function of signal wavelength is also investigated at these pump wavelengths     

Design and Control of Gain-Flattened Erbium-Doped Fiber Amplifier for WDM Applications

A simple experimental method to design gain-flattened erbium-doped fiber amplifier is proposed and demonstrated based on the two linear relations between the output power and the pump power, and between the gain and the length of the erbium-doped fiber at the gain flattened state. The spectral gain variation of the erbium-doped fiber amplifier constructed by this method was less than 0.4 dB over 12 nm (1,545~1,557 nm) wavelength region. The gain flatness is also controlled within 0.4 dB over the input power range of ?30 15 dBm/ch through the feedback control utilizing the amplified spontaneous emission power in the 1,530 nm region.     

Highly efficient Er-doped fibre amplifiers pumped in 660 nm band

High gain coefficient in an erbium-doped fibre amplifier, 3.8 dB/mW at 1.536 mu m and 2.3 dB/mW at 1.552 mu m, is achieved for a pump wavelength of 664 nm by using an erbium-doped fibre with a high numerical aperture of 0.285 and thermally-diffused expanded core fibre ends. The gain at 1.536 mu m reaches 30 and 35 dB for launched pump powers of 10 and 15 mW, respectively.<>     

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.     

Dependence of performance of saturated in-line erbium-doped fiberamplifiers on pump wavelength around 1480 nm

The effect of pump wavelength around 1480 nm on the performance of saturated erbium-doped fiber amplifiers (EDFAs) suitable for use as in-line amplifiers for terrestrial and submarine systems is investigated experimentally. The results show that for high-gain amplifiers (25 dB) with high output powers (15 dBm), operating around 10 dB in compression, the performance is relatively insensitive to pump wavelength. However, for lower gain amplifiers (12 dB), pumped at low (15 mW) powers, the compression of the amplifier is found to decrease significantly with increasing pump wavelength, while the noise figure shows a weak minimum for a pump wavelength near 1480 nm     

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。     

Optimum position of isolators within erbium-doped fibers

An isolator is used as an amplified spontaneous emission suppressing component within an erbium-doped fiber. The optimum isolator placement is both experimentally and theoretically determined and found to be slightly dependent upon pump power. Improvements of 4 dB in gain and 2 dB in noise figure are measured for the optimum isolator location at 25% of the fiber length when the fiber is pumped with 60 mW of pump power at 1.48 μm