C+L波段宽带增益平坦铋基掺铒光纤放大器的设计

基于光纤放大器增益谱的宽带平坦化发展需要,设计了一个两段铋基掺铒光纤(Bi-EDF)级联并携带一个C波段(1 530~1 565 nm)宽带光纤布拉格光栅(FBG)的双通结构型铋基掺铒光纤放大器(Bi-EDFA),从理论上研究了其对输入信号的放大特性。研究表明:FBG的引入可以使C和L波段(1 570~1 620 nm)信号分别经历不同长度Bi-EDF的双向传输,各自获得高增益放大,实现增益谱的宽带平坦化。在200 mW的1 480 nm双向对称泵浦下,第一级和第二级Bi-EDF长度分别为50 cm和170 cm时,对于波长间隔为2 nm、每路功率为-30 dBm的56路C+L波段信号的输入,Bi-EDFA高于30 dB的增益带宽达到了90 nm(1 530~1 620 nm),平均增益为35.7 dB,增益起伏仅为2.3 dB。同时,噪声系数得到明显改善。研究结果对于研制具有宽带、增益平坦的C+L波段Bi-EDFA具有实际指导意义。     

Novel fiber design for flat gain Raman amplification using single pump and dispersion compensation in S band

This paper reports on a novel fiber design that has an inherently flattened effective Raman gain spectrum. Simulations show that gain-flattened broad-band Raman amplification, using a single pump, can be achieved in any wavelength band by suitably choosing the fiber parameters and the pump wavelength. The fiber also has a high negative dispersion coefficient-(380-515) ps/km/spl middot/nm over the operating range of wavelengths-and the shape of the dispersion curve is such that the total link dispersion can be not only compensated but also flattened. Hence, the designed fiber can serve as a lossless, broad-band, dispersion-flattening, and dispersion-compensating module for the S band, wherein lossless operation is achieved using inherently gain-flattened single-pump Raman amplification. The performance characteristics of such a module was modeled taking into account wavelength-dependent splice loss as well as background loss, and it has been shown through simulations that lossless operation with /spl plusmn/0.2-dB gain ripple is achievable over (1480-1511) nm using a single pump. Moreover, dispersion compensation for five spans of transmission in a 10-Gb/s system, over this 32-nm bandwidth in the S band, should be attainable using the proposed design.     

环形腔光纤激光器波长选择技术

用波分复用 (WDM)光栅串作环形腔端镜 ,调节F P滤波器透过的共振波长 ,实现对应光栅波长的稳定激光输出 ,其斜率效率在 0 0 9左右 ,实验表明光栅反射率以及所处波长处的增益影响激光阈值的大小。用全反镜替代光栅串 ,在 15 30～ 15 75nm范围内可对输出波长进行连续调节。     

DBR单纵模光纤激光器波长温度调谐

报道了采用DBR方式,利用8 mm的高浓度掺Yb3+单模光纤,实现了波长为1 064 nm的单纵模调谐激光稳定输出的实验结果。该DBR谐振腔有效腔长为16 mm,输出最大功率为7.4 mW,通过半导体制冷器温控改变谐振腔的温度,实现了0.824 nm的单纵模无跳模调谐。采用光纤外差法,并利用低损耗环形器和光纤反射镜倍增延迟线长度提升测量精度的方式,测量得到激光最大线宽为4.4 kHz。单纵模激光的弛豫震荡峰位于900 kHz处,其相对强度噪声为-110 dB/Hz,当频率大于1.5 MHz时相对强度噪声为-145 dB/Hz。     

A 980-nm band laser diode pump source with a detuned wavelength of1000 nm for praseodymium-doped fiber amplifiers

By using practical high-power 980-nm band laser diodes, efficient direct pumping for a praseodymium-doped fiber amplifier (PDFA) is achieved. The lasing wavelength is detuned from 980 to 1000 nm by selective optical feedback from a fiber grating     

1 532 nm全光纤Er/Yb共掺杂激光器

近年来,相干探测激光雷达是测量远距离低空风切变的有效手段,1.6 μm波段固体激光器以其人眼安全、探测器件成熟等优势成为相干雷达主要光源。其增益介质Er:YAG晶体在1532 nm波段有较强的吸收峰,但吸收谱较窄,因此通过使用1 532 nm光纤激光器进行谐振泵浦可以有效提高晶体输出效率。为此,文中以Er/Yb双包层光纤为增益介质,1532 nm光纤光栅为反射腔镜,976 nm半导体激光器为泵浦源,实现了全光纤化1532 nm激光输出。输出激光最大功率73.44 W,波长可调谐范围为1531.35~1532.14 nm,波长谱宽为0.06 nm,x和y方向的光束质量M2分别为1.38和1.26,是1.6 μm固体激光器的理想泵浦源。并采用此激光器泵浦Er:YAG非平面环形腔获得1.3 W单频激光输出,斜率效率为31.76%。     

Widely tunable wavelength spacing dual-wavelength single longitudinal mode erbium doped fiber laser

A simple widely tunable wavelength spacing dual-wavelength single longitudinal mode (SLM) erbium doped fiber laser (EDFL) based on cascaded fiber Bragg gratings (FBGs) and birefringent fiber filter is proposed and demonstrated. Experimental results show that the lasing wavelength spacing is widely tunable in a range from 2 nm to 18 nm, which has potential to generate frequency tunable terahertz (THz) waves by beating the lasing dual-wavelength in a high speed photodetector. The birefringent fiber filter acts as an ultra-narrow bandpass filter and benefits the simultaneous oscillation of dual-wavelength in a single laser cavity. The output peak power of the lasing dual-wavelength is approximately equalized at room temperature, and a high optical signal-to-noise ratio (OSNR) is realized in the whole tuning range. The SLM operation of dual-wavelength fiber laser is verified by Fabry–Perot (F–P) scanning interferometer, and the clear eye diagram proves that the proposed fiber laser is effective in the application of fiber optic communication system.     

全光纤型Er/Yb共掺光纤短腔激光器

报道了一种高输出功率、高斜率效率的短腔ErYb共掺杂光纤激光器。激光谐振腔由一段ErYb共掺杂单模光纤与一对布拉格反射波长相同的光纤布拉格光栅(FBG)组成。反射率为60%的光纤光栅用作光纤激光器谐振腔的输出,3dB带宽为016nm。反射率为99%的光纤光栅作为高宽带反射腔镜,同时作为抽运光输入端,3dB带宽102nm。以980nm激光二极管(LD)作抽运源进行实验。使用不同的抽运功率分别测量不同长度的ErYb共掺杂光纤,优化光纤激光器谐振腔得到的最佳长度仅为13cm。即选用13cmErYb共掺杂光纤作为增益介质来制作短腔ErYb光纤光栅激光器,最大输出功率可达11mW,输出功率稳定性<±001dB,抽运阈值功率为35mW,斜率效率为153%,测量其15522nm激光的输出光谱,25dB线宽为03nm,边模抑制比>60dB,波长稳定性为005nm。可用于密集波分复用(DWDM)系统。     

单偏振双波长非保偏有源掺杂光纤激光器

利用宽带保偏光纤光栅(PFBG)、普通有源光纤和窄带普通光纤光栅构成独立的谐振腔,且窄带普通光纤光栅的中心波长分别与保偏光纤光栅的一个反射峰波长对准,可以输出稳定的双波长/单波长的单偏振激光.利用这一思想,制成了基于非保偏有源掺杂光纤的单偏振双波长光纤激光器.实验结果表明,双波长同时激射时的激光消光比为46.7 dB,单波长激光的消光比为59.6 dB,滤波出单波长测量其偏振度为98.5%.这种激光器在微波光子领域可用于在光域产生微波.     

A broad-band single polarization optical fiber

The authors report on a single-mode optical fiber that transmits one and only one polarization state of the fundamental mode over a broad wavelength band (13%). The good broadband performance is attributed to the fiber's refractive-index profile, which mathematically allows only one polarization state to cutoff. The authors discuss general design principles and show that the mode field diameter is a qualitative indicator of the fiber's performance. The fiber's guided polarization state is similar to the fundamental mode of a step-index fiber in its low attenuation, 5.5 dB/km, and small mode diameter, 5.8 μm (both measurements at 840 nm). Most important, the fiber shows a broad single polarization band, 13%, a feature well described by the change in mode field diameter with wavelength of an ideal, circularly symmetry, W -profile fiber     

Rapid continuous tuning of a single-polarization fiber ring laser

We have developed and studied what we believe is the first fiber laser operating in a single polarization at 1550 nm with PM fiber output and capable of wavelength tuning over a 20-nm bandwidth in less than 50 μs. The fast wavelength tuning speed in a fiber laser is achieved by incorporating an acousto-optic tunable filter into the laser. The same filter is used in an optoelectronic feedback loop to suppress the relaxation oscillations induced by wavelength transitions     

180 W单频全光纤激光器

高功率单频光纤激器在相干探测、功率光谱合成等方面具有广泛的应用前景。分析了高功率单频光纤激光器中受激布里渊散射效应的抑制方法,研究了放大级特性对受激布里渊散射效应的影响。采用线宽为70 kHz的单频光纤激光器作为种子源,经两级光纤放大,实现了中心波长1 064.1 nm、线宽70 kHz、最高功率为180 W的单频全光纤激光输出,光-光转换效率71.1%,光束质量Mx2=1.2,My2=1.21。分析了改变放大级特性前后输出功率提升的原因,认为改变放大级的温度分布减小了受激布里渊散射效应的增益系数,提高了输出激光的受激布里渊散射阈值,促使改变放大级温度分布后的输出功率大幅提高。该激光器的输出功率仅受限于泵浦功率,进一步提高泵浦功率,有望实现更高功率的单频光纤激光输出。     

Multi-wavelength Raman fiber laser with 2- and 3-stage cavities in a phosphosilicate fiber

We report on the simultaneous Raman lasing of three wavelengths at 1428/1454/1495 nm in a single P-doped optical fiber, by use of the stimulated Raman scattering of both P₂O₅ and SiO₂/GeO₂. The laser is formed with fiber Bragg grating cavities and the destination laser wavelengths are obtained through respective two- and three-stage Raman cascading processes for efficient wavelength conversion. Thermally controllable power ratios between the wavelengths have been realized by temperature detuning the most efficient 2-stage resonant wavelength at 1495 nm. With a comparable power level at each wavelength, the maximum total power achieved in our multi-wavelength Raman laser is 2.87 W in a fiber length of 700 m pumped with a 20 W double clad Yb fiber laser.     

运用波长与光纤长度关系选择激光波长

推导了掺Yb 光纤激光器中激射波长与掺杂光纤长度、掺杂浓度等的关系式。依据所得到的关系式,在981.5 nm 半导体激光抽运的掺Yb 环形腔石英光纤激光器中,获得了中心波长在1053nm 的激光输出。光抽运阈值功率为1.85 m W。激光半功率宽度(FWHM)为5 nm ,输出功率为104μW,斜率效率为3% 。激光空间模式为基横模。     

飞秒写制长周期光纤光栅的液体浓度测量实验研究

利用逐点写入法在去涂敷层的普通单模通信光纤中直接写入了长周期光纤光栅(LPFG),实验获得的LPFG在C波段的谐振波长1 538.8nm,衰减强度达10.63dB。其氯化钠和蔗糖溶液浓度传感特性实验表明,随着盐溶液浓度的增大,LPFG的谐振波长向左线性漂移,盐浓度每增加1%,波长向左漂移约0.05nm;随着糖溶液浓度从0%增大为50%,LPFG的谐振波长向左非线性漂移量高达约8nm。实验结果表明:飞秒激光逐点写入法操作简单,容易控制诱导的周期性折射率微扰在纤芯和或包层的位置,从而制备出对低浓度液体敏感的LPFG化学传感器;同时飞秒激光写制的LPFG具有较高的外界环境灵敏度,有望用在化学浓度传感中。     

58kW高峰值功率窄线宽纳秒脉冲光纤激光器

报道了一种峰值功率58 kW的窄线宽纳秒脉冲光纤激光器,由窄线宽种子源加4级光纤放大的主振荡功率放大(MOPA)结构组成。窄线宽种子源输出的连续种子光经电光强度调制器调制为纳秒脉冲信号光,经4级光纤放大,输出峰值功率达58 kW的窄线宽脉冲激光,中心波长106431nm,平均功率569W,重频100kHz,脉宽98ns,斜效率717,光束质量M2=134,偏振消光比156dB。激光功率的进一步提升受限于次脉冲及自相位调制。该高峰值功率窄线宽纳秒脉冲光纤激光器可在激光雷达中得到应用。     

由高双折射光纤环镜构成的可变波长输出的L-波段掺铒光纤激光器

报道了一种结构简单的可变波长输出的L 波段线型腔掺铒光纤激光器。其中的波长选择器件为一包括两段高双折射光纤在内的光纤环镜 ,通过调整环镜内偏振控制器的状态可以改变环镜对不同波长的反射率以获得可变波长输出的效果。线型腔内用 980nm激光抽运铒光纤产生的ASE作二次抽运源 ,使腔内铒光纤的增益谱由C 波段位移到L 波段。实验中观察到波长在 1 5 83～ 1 6 0 0nm范围内可变的稳定激光输出 ,波长调谐范围为 1 7nm     

8-mV threshold Er/sup 3+/-doped planar waveguide amplifier

We report on the gain characteristics of a low threshold (8 mW) Er/sup 3+/-doped planar optical waveguide amplifier. Net fiber to fiber gain of 4.5 dB is achieved at a signal wavelength of 1536 nm with 80 mW of 980-nm pump power. This device represents significant progress toward a planar amplifier module pumped by a single laser diode.     

1.52-1.59-μm range different-wavelength modulator-integratedDFB-LDs fabricated on a single wafer

We report for the first time different-wavelength modulator-integrated distributed-feedback laser diodes (DFB/MODs) fabricated on a single wafer, whose lasing wavelength cover almost all of the expanded erbium-doped fiber amplifier (EDFA) gain band from 1.527 to 1.593 μm. The devices provided uniform and high-performance characteristics such as a threshold current less than 12 mA and successful transmission of 2.5 Gb/s-600 km through a normal fiber     

Wavelength-tunable thulium-doped single mode fiber laser based on the digitally programmable micro-mirror array

We propose a wavelength-tunable thulium-doped single mode fiber laser with a digitally controlled micro-mirror array device. The fast and flexible lasing wavelength switching property was achieved by the pixelated spatial modulation of the micro-mirror array. The proposed laser provides a maximum output power of 160 mW with 24% slope efficiency and a narrow output linewidth of less than 0.03 nm. The operating wavelength is continuously tunable from 1863 nm to 1937 nm with a wavelength selectivity accuracy of less than 0.4 nm and a fast switching time of ∼75 μs.