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     

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.     

980 nm和1480 nm LD混合泵浦两段级联掺铒光纤放大器实验研究

采用两段级联掺铒光纤、９８０ｎｍ和１４８０ｎｍＬＤ混合泵浦方式，实验分析比较了内插光隔离器和内插光隔离－耦合环光路结构掺铒光纤放大器（ＥＤＦＡ）的增益、噪声系数和输出功率特性。研制出内插光隔离－耦合环的ＥＤＦＡ，在信号波长１５５３．５ｎｍ处，小信号增益为４２．８ｄＢ，噪声系数为４．４ｄＢ，输出功率为１５．２ｄＢｍ。     

Inherent enhancement of gain flatness and achievement of broad gainbandwidth in erbium-doped silica fiber amplifiers

We report new methods to inherently increase the flatness and bandwidth of erbium-doped silica fiber amplifiers from three perspectives: fiber design, pump-signal WDM coupler optimization, and amplifier structure. First, to achieve inherent control of the gain spectrum, a new type of composite fiber structure with an Er-doped core and a Sm-doped cladding ring is proposed and experimentally demonstrated. Interaction of the optical field with the Sm-doped cladding to produce evanescent wave filtering is modeled, which provides an in-line control of gain fluctuation in the erbium-doped flier amplifier (EDFA) C band, 1530-1560 nm. Second, the effect of the spectral characteristics of WDM couplers over the L band of an EDFA is explored. A fused taper fiber coupler for a 1480-nm pump is optimized for signals in the wavelength range of 1570-1610 nm by measuring the small-signal gain, gain tilt, and noise figure in an L-band EDFA. Finally, a new all-fiber structure for a wide-band EDFA, where the L and C bands were coupled serially, is demonstrated with optimized pump-signal couplers. Further optimization of the new composite fiber structure and the transient effects in the serially coupled EDFAs are also discussed     

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     

New pump wavelength of 1540-nm band for long-wavelength-band erbium-doped fiber amplifier (L-band EDFA)

A long-wavelength-band erbium-doped fiber amplifier (L-band EDFA) using a pump wavelength source of 1540-nm band has been extensively investigated from a small single channel input signal to high-power wavelength division multiplexing (WDM) signals. The small-signal gain coefficient of 1545-nm pumping among the 1540-nm band is 2.25 times higher compared to the conventional 1480-nm pumping. This improvement in gain coefficient is not limited by the pumping direction. The cause for this high coefficient is explained by analyzing forward- and backward-amplified spontaneous emission spectra. The gain spectra as a function of a pump wavelength suggest that a broadband pump source as well as a single wavelength pump can be used as a 1540-nm-band pump. In the experiment for high-power WDM signals, the power conversion efficiency for 256 WDM channel input is 48.5% with 1545-nm pumping. This result shows more than 20% improvement compared with the previous highest value for the L-band EDFA. Finally, the 1545-nm bidirectionally pumped EDFA is applied as a second stage amplifier in an in-line amplifier of an optical communication link with a 1480-nm pumped first stage EDFA, in which the input power of the second-stage EDFA is +2.2 dBm. The power conversion efficiency yields a 38% improvement without noise figure degradation compared with the case of 1480-nm pumping.     

Improvement of gain and noise figure in double-pass L-band EDFA by incorporating a fiber Bragg grating

An obvious improvement on both the gain and noise figure (NF) is demonstrated in the new double-pass L-band erbium-doped fiber amplifier (EDFA) with incorporating a fiber Bragg grating (FBG). Compared with the conventional L-band EDFAs, the gain is improved by about 6 dB in the new configuration for a 1580-nm signal with an input power of -30 dBm at 60 mW of 980-nm pump power. It is important that the NF is greatly reduced in the new configuration, as the FBG greatly compresses the backward amplified spontaneous emission. For the economical utility of pump power and erbium-doped fiber length, such a configuration may be a very competitive candidate in the practical applications of L-band EDFAs.     

Gain enhancement in L-band loop EDFA through C-band signal injection

Gain enhancement provided in L-band erbium-doped fiber amplifier (EDFA) with loop configuration and through C-band signal injection is experimentally demonstrated and compared with conventional single-stage L-band EDFA design. Significant backward amplified spontaneous emission suppression in C-band and pump conversion efficiency increase in L-band were observed for varying C-band seed signal wavelength and power levels. Gain and noise figure (NF) performance of loop design L-EDFA is compared with the conventional bidirectionally pumped single-stage L-EDFA design. Gain and NF measurements in the loop configuration have resulted in an up to 9.5-dB increase in gain and up to 2.6-dB degradation in NF at a moderate signal wavelength of 1585 nm.     

反射式L波段掺铒光纤放大器增益与噪声指数改善

提出了一种改善反射式L波段掺铒光纤放大器增益和噪声指数的方法,即在放大器的输入端插入一泵浦源,通过提高信号输入端的粒子数反转率实现提高增益和降低噪声指数的目的.通过仔细调整两个泵浦源的输出功率,与单泵浦结构相比,在相同条件下,在1565～1615 nm波长范围内,小信号增益提高了1.5～9.9 dB,噪声指数下降了1.3～9.4 dB.     

795 nm and 1064 nm dual pump thulium-doped tellurite fibre for S-band amplification

Gain measurement in thulium-doped tellurite fibre is demonstrated with a maximum internal gain of 7 dB at 1480 nm. An improvement in gain by a factor of 2 is achieved using a 795 nm and 1064 nm dual pump scheme. Gain in tellurite fibres extends to longer wavelength than in fluorides, showing improved overlap with the C-band EDFA.     

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     

具有动态增益均衡特性的低噪声全光增益箝位EDFA

针对全光增益箝位EDFA噪声指数恶化以及用于WDM系统时增益动态变化两个问题,提出具有动态增益均衡特性的低噪声全光增益箝位EDFA,在35 nm范围内,输入信号功率在-40 dBm到0 dBm之间变化时,增益变化被箝制在1 dB范围内,同时保持单波长输入噪声指数<4.5 dB,多波长输入增益谱不平坦度<0.4,噪声指数<5.5 dB,有效解决了以上问题.     

Erbium-doped optical fiber amplifiers pumped in the 660- and 820-nmbands

State-of-the-art erbium (Er)-doped optical fiber amplifiers (EDFA's) pumped in the 660- and 820-nm bands are described. We have demonstrated highly efficient EDFA's incorporating optimized 664- and 827-nm pump wavelengths and an Er-doped high numerical aperture (NA) fiber with thermally diffused expanded core (TEC) fiber ends. Gain coefficients of 3.8 and 1.3 dB/mW at respective wavelengths of 664 and 827 nm were achieved at a signal wavelength of 1535 nm. Noise figures of 3.1 and 4.1 dB at respective pump wavelengths of 670 and 827 nm were obtained at a signal wavelength of 1535 nm. A highly efficient Er-doped fiber amplifier module, in which an AlGaInP visible laser diode (LD) was used as the pump source, was successfully developed as a practical application of this technology. A maximum overall gain coefficient of 3.0 dB/mW was achieved at a signal wavelength of 1535 nm. The EDFA module realized a maximum overall signal gain of 33 dB at 1535 nm with a saturated output power of -1 dBm. A maximum saturated output power of 3.9 dBm was obtained at a signal wavelength of 1552 nm. The present EDFA design using a low-cost laser diode for optical disk memory use and a high NA Er-doped fiber has great potential for providing inexpensive, high-performance EDFA's     

铋镓铝共掺的高浓度掺铒光纤及放大器

研制出了铋镓铝共掺的高浓度掺铒光纤,这种掺铒光纤在1 530 nm处的吸收系数达到了28.5 dB/m.利用这种铋镓铝共掺的高浓度掺铒光纤制成了C波段和L波段的掺铒光纤放大器(EDFA),测试这两种放大器的荧光谱和增益谱线.利用2.5 m的高浓度掺铒光纤制作的C波段EDFA就实现了高增益.利用10 m这种掺铒光纤制作的L波段放大器实现了有效的I波段放大.     

新型掺铒光纤的制备和研究

根据EDFA的性能要求,制备了纤芯掺Al的掺铒光纤,在980nm波长、131mW泵浦功率的泵浦条件下当输入信号功率为-15dBm时在C-band实现了35dB左右的增益,其增益平坦度小于1dB。这种掺铒光纤的饱和输出功率在17.5dBm以上,功率转换效率为44.18%,能应用于C-band的各类掺铒光纤放大器中。     

Six-wavelength Raman fibre laser for C- and L-band Ramanamplification and dynamic gain flattening

A novel six-wavelength Raman fibre laser exhibiting a dynamic gain flattening capability in the C + L optical telecommunications band is demonstrated. The power distribution in the six lasing wavelengths is adjusted with voltage-controlled Bragg-grating output couplers. The fibre laser was used as a pump source for distributed Raman amplification in several transmission span lengths. For example, the multiwavelength laser provides an on/off gain of 19 dB over a 100 km span of True-Wave RS optical fibre. The measured gain flatness is 1.7 dB peak-peak and the effective noise figure ranges from 1.6 to -5.2 dB in the 1530 to 1600 nm bandwidth     

1480nmLD泵浦掺铒光纤放大器的增益带宽特性的研究

采用国产１４８０ｎｍＬＤ及优化的掺铒光纤，研制成光纤增益达３２ｄＢ、最大输出功率为１０ｄＢｍ、带宽大于２５ｎｍ的掺铒光纤放大器模块（其纤入纤出净增益为２７ｄＢ、输出功率为７ｄＢｍ）。讨论了放大器的增益、带宽特性及ＡＳＥ对放大器测量的影响。     

Experimental optimisation of central wavelength and bandwidth of reflective FBG for efficiency improvement of low-noise L-band EDFAs

Operation of L-band erbium-doped fibre amplifiers (EDFAs) incorporating a reflective amplified spontaneous emission filter (fibre Bragg grating (FBG)) was emulated with a tunable source. The experimental optimisation of the FBG bandwidth and central wavelength led to a low noise (<5.2 dB) 20 dBm single-pumped WDM EDFA.     

Millimeter‐Wave High‐Linear CMOS Low‐Noise Amplifier Using Multiple‐Gate Transistors

A millimeter‐wave (mm‐wave) high‐linear low‐noise amplifier (LNA) is presented using a 0.18 µm standard CMOS process. To improve the linearity of mm‐wave LNAs, we adopted the multiple‐gate transistor (MGTR) topology used in the low frequency range. By using an MGTR having a different gate‐source bias at the last stage of LNAs, third‐order input intercept point (IIP3) and 1‐dB gain compression point (P_1dB) increase by 4.85 dBm and 4 dBm, respectively, without noise figure (NF) degradation. At 33 GHz, the proposed LNAs represent 9.5 dB gain, 7.13 dB NF, and 6.25 dBm IIP3.     

Evaluation of the 800 nm pump band for erbium-doped fiberamplifiers

Performs a comprehensive experimental and theoretical investigation of methods for overcoming the excited-state absorption (ESA), which is the main obstacle to efficient pumping of erbium-doped fiber amplifiers (EDFAs) at 800 nm. The effects of ESA on gain can be reduced at the cost of an additional noise penalty by adopting bidirectional pumping or by pumping in the long-wavelength tail of the ground-state absorption (GSA) band. The GSA and ESA cross-section spectra on the glass host material. One of the most promising hosts, fluorophosphate, is compared to Al/P silica in a detailed analysis based on a quantitative numerical model. It is predicted that 2-3 dB less pump power is required for the fluorophosphate EDFA. For Al/P-silica EDFAs, it is found that ~7-dB-higher power is required when pumping in the 800 nm band than for pumping at 980 and 1480 nm