非线性光纤环：2.掺铒光纤全纤光学双稳态实验

利用掺饵光纤和光纤定向耦合器组成全光纤谐振腔，在光学非线性条件下，实现了全纤光学双稳运转，实验双稳阈值与理论相符。     

掺铒光纤中的双稳态现象的研究

在以掺铒光纤为增益介质的环形光纤激光器中观察到了光学双稳态现象,定性分析了双稳态形成的机理,即掺铒光纤不同位置分别存在增益饱和和吸收饱和,而且吸收饱和有着更低的饱和阈值。通过理论衍生的公式对增益特性曲线进行了拟合,并结合增益特性曲线对光双稳态的产生给出了定量的解释。     

基于非线性偏振旋转效应的多波长光纤激光器

多波长光纤激光器是未来波分复用光通信系统的理想光源,提出和展示了一个基于非线性偏振旋转效应的多波长光纤激光器,非线性偏振旋转诱导的强度相关非均匀损耗能有效地抑制均匀加宽增益介质掺铒光纤中的模式竞争,从而使光纤激光器在室温下产生稳定的多波长输出,实验实现了最多18个波长的多波长输出.另外,此激光器没有使用传统的滤波器,而是在激光腔内插入一段保偏光纤,保偏光纤与偏振相关隔离器构成一等效Lyot双折射光纤周期性滤波器.利用这种在线型的双折射光纤滤波器简化了光纤激光器的结构,使它更易于集成.还实验研究了多波长输出随抽运功率的演化,发现抽运功率对多波长的均匀性影响很大.     

用偏振烧孔实现的室温双波长光纤激光器

本文提出一种简单的掺铒光纤激光器的结构,在室温下实现了稳定的双波长激光运转.在该结构中,使用刻写在保偏光纤上的光纤布喇格光栅作为波长选择器件. 实验表明,通过调整偏振控制器的状态,在室温下能够得到稳定的双波长激光输出,波长间隔0.52 nm,16次重复扫描对应于每一波长的振幅变化及波长间振幅差异均小于0.2 dB.     

基于多波长类噪声脉冲的掺铒光纤激光器

报道了一种基于多波长类噪声脉冲的被动锁模掺铒光纤激光器。采用980 nm半导体激光器作为泵浦源，2.5 m长的掺铒光纤作为增益介质。锁模机制为非线性放大环形镜(NALM)。通过自相关迹证明输出脉冲为类噪声脉冲。该类噪声脉冲的光谱3 dB带宽可达17.2 nm，边模抑制比为47.7 dB，重复频率为5.434 MHz，单脉冲能量为7.9 nJ。为了实现平坦的多波长输出，在NALM结构中加入Sagnac环干涉仪，获得了最大波长数为5的平坦多波长类噪声脉冲，平坦度为1.995。     

L波段线型腔波长可调谐掺铒光纤激光器

报道了工作波长在L波段的由两个光纤环境构成线型谐振腔的掺铒光纤激光器，通过调整环境中偏振控制器的状态来改变环境对不同波长的反射率以实现某些波长的激光输出。线型腔内的激光工作介质为两段不同掺杂浓度的掺铒光纤，其中一段铒光纤由一980nm激光器抽运，其产生的放大自发辐射谱在腔内再同时对两段掺铒光纤进行抽运，使它们的增益谱移位到L波段。实验中观察到了波长从1566．4nm到1592.4nm范围内可调的稳定的连续激光输出，其波长调谐范围达26nm。     

48-波长线形腔多波长掺铒光纤激光器

采用两个光纤环镜作为腔镜构成线形腔可调谐多波长掺铒光纤激光器.将铒光纤浸入77 K的液氮中,选择可调谐光纤环镜作为输出腔镜,利用Mach-Zehnder干涉仪的滤波特性和输出端光纤环镜反射率的宽带可调特性,获得了波长间隔～0.4 nm、最大波长数目48个的多波长激光的稳定输出,同时实现了在1525～1555 nm范围内,多波长激光运转区域的灵活调节.     

S波段可调谐掺铒光纤激光器的实验研究

提出了一种结构简单的S波段环形腔可调谐光纤激光器.研究了输出功率随激光波长和抽运功率的变化关系以及激光器运转的稳定性.当抽运功率113 mW时,通过调节全光纤可调谐法布里珀罗滤波器,在1482.73～1520.75 nm范围内得到了稳定的激光输出,3 dB带宽小于0.03 nm.其中1487.70～1520.75 nm范围内输出功率大于5 dBm,边模抑制比大于60 dB.1499.02 nm处最大输出功率7.11 dBm,输出功率起伏小于0.04 dB.     

基于光纤布拉格光栅对的双波长线形腔掺铒光纤激光器设计与优化

基于光纤布拉格光栅对（DFBGs）的双波长线形腔光纤激光器利用偏振烧孔效应实现双波长激光稳定输出的研究颇多,但有关3 dB光纤环形镜（FLM）与光纤布拉格光栅（FBG）构成腔镜或仅FBG构成腔镜,以及DFBGs的选择对其激光输出性能[光信噪比（OSNR）、斜率效率及稳定性等]的影响的研究很少。本文实验首先在双波长线形腔掺铒光纤激光器中比较了3 dB FLM与FBG构成腔镜和仅FBG构成腔镜的双波长激光的输出性能,结果表明,仅FBG构成腔镜的输出性能优于3 dB FLM与FBG构成腔镜的输出。其次在仅FBG构成腔镜的线形腔中对低反射率FBG（输出镜）反射率相同与不同时的输出性能进行了对比,研究表明,低反射率FBG的反射率相同时双波长激光输出具有较高的OSNR、斜率效率和稳定性。接着改变构成腔镜的两对FBG的中心波长间隔分别为4、8、12 nm,研究表明,中心波长间隔越大输出越稳定,OSNR越高,但激光器的斜率效率有所降低。最后在室温环境下实现了两个激光波长分别为1550 nm和1562 nm、OSNR分别为50.24 dB和51.19 dB左右、中心波长变化分别小于0.030 nm和0....     

基于过耦合器的L波段可变波长掺铒光纤激光器

研究了一种新型的光纤环形镜(FLM)的原理和特性,这种FLM是由耦合比对波长变化的耦合器即过耦合器和偏振控制器(PC)构成,改变PC的状态,可以调节环的反射谱位置和深度.与高双折射光纤环形镜构成线型谐振腔,调整光纤环内PC的状态可以改变环对不同波长的反射率,控制腔内的增益从而输出可变波长的激光.实验得到输出波长在156...     

Multiwavelength erbium-doped fiber laser employing a nonlinear optical loop mirror

A stable and broad bandwidth multiwavelength erbium-doped fiber laser is proposed and demonstrated successfully. A nonlinear optical loop mirror which induces wavelength-dependent cavity loss and behaves as an amplitude equalizer is employed to ensure stable room-temperature multiwavelength operation. Up to 50 wavelengths lasing oscillations with wavelength spacing of 0.8 nm within a 3-dB spectral range of 1562-1605 nm has been achieved. The measured power fluctuation of each wavelength is about 0.1 dB within a 2-h period.     

A novel double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror

In the paper, a ring double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror filter is demonstrated, in which the non-linear amplified fiber loop mirror (AFLMF) is used as a filter. At the 980 nm pump power of 10.29 dBm, the tunable laser source center wavelength of 1563 nm and power of −3 dBm, up to 12 even output channels with 0.16 nm spacing are achieved. At the same time, we study the influence of 980 nm pump power, the polarization controller and the tunable laser source center wavelength on the number of Stokes light wave.     

Reflectivity characteristics of the fiber loop mirror with a polarization controller

In this paper, reflectivity characteristics of a fiber loop mirror (FLM), which is formed by inserting a fiber polarization controller (PC) into the fiber loop of an ordinary FLM, are investigated in detail. A theoretical model for determining the reflectivity characteristics of the FLM is present by using the equivalent optical path technique, and the reflectivity characteristics of the FLM are then simulated with the model. The simulation results show that, when the FLM is based on a 3 dB optical coupler (OC), the reflectivity of the FLM may be continuously adjusted to any value between 1 and 0 by changing the PC state, i.e. by either changing the fast axis orientation or the birefringence intensity of the PC alone, as well as both of them; the reflectivity spectra of the FLM are wide and flattened for any PC state, mainly limited by the operating bandwidth of the OC used. The reflectivity characteristics of the FLM are further tested experimentally. The results verify that the reflectivity of the FLM may truly be continuously adjusted between its maximum and minimum values by changing the PC state. The obtainable maximum and minimum reflectivities of the FLM are measured to be 93% and 2%, respectively. Moreover, the experimental results are in agreement with those of the simulations.     

基于高双折射Sagnac环的可调环形腔掺铒光纤激光器理论与实验研究

报道了一种利用偏振控制器（PC）和保偏光纤（PMF）组成的高双折射Sagnac干涉环实现选频和调谐的环形腔掺铒光纤激光器.理论模拟了PMF和PC对波长的控制作用.实验中调节PC得到了单波长、双波长和多波长激光;并验证了滤波间隔随PMF长度的变化规律.实验中得到了斜率效率20%,3 dB线宽0.016 nm,30 dB线宽0.097 nm,边模抑制比（SMSR）40 dB左右的稳定激光输出. 关键词： 光纤激光器 Sagnac干涉环 环形腔 掺铒光纤     

利用偏振控制器连续调节光纤环镜的反射率

研究了一种新型光纤环镜(FLM)的原理与特性，这种FLM由在普通光纤环镜中插入光纤型偏振控制器(PC)构成.通过等效光路分析建立了该FLM的理论模型，并对其反射特性进行了数值模拟.研究表明，通过改变PC的状态，即改变其双折射效应的快轴取向或强度，可连续调节FLM的反射率，反射率谱具有宽带特性，主要受光纤耦合器工作带宽的影响.此外，对FLM的反射特性还进行了实验研究.实验结果也证实，通过调节PC状态，FLM反射率可在其最大和最小值之间连续调节，实验测得FLM最大和最小反射率分别可达93%和2%.根据PC双折 关键词： 光纤环镜 偏振控制器 光纤耦合器 反射率     

Switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

Without the need of any other additional filtering device, a triple-wavelength switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber is newly proposed and experimentally demonstrated. Three potential lasing wavelengths at about 2.0 nm interval with the side mode suppression ratio higher than 40 dB can be switched mainly by adjusting a polarization controller next to the few-mode high birefringence fiber in the Sagnac loop. In addition to the stable single-line lasing operation, simultaneous dual- and triple-line oscillations are also highly stable at room temperature with suppressing the intrinsic homogeneous gain broadening of the erbium-doped fiber.     

Switchable dual-wavelength erbium-doped fiber-ring laser based on one polarization maintaining fiber Bragg grating in a Sagnac loop interferometer

A switchable erbium-doped fiber-ring laser providing dual-wavelength outputs with orthogonal polarizations when operating at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 42 dB. The amplitude variation over 90 min is less than 0.6 dB for both wavelengths.     

基于偏振保持掺Er3+光纤的高稳定性单波长光纤激光器

研制出光敏偏振保持掺Er³⁺光纤,通过在这种光纤上紫外写入三个光纤光栅,形成对抽运激光高转化效率的谐振腔.在输出功率为23.617dBm、工作波长为976nm的激光抽运下,得到均值功率为9.20dBm、均值中心波长为1554.554nm的单波长激光输出.在室温下800min（约13.3h）的测量时间内,其输出功率的波动为±0.05dB,中心工作波长的波动为±0.0015nm. 关键词： 光纤激光器 3+光纤')" href="#">偏振保持掺Er³⁺光纤 光纤Bragg光栅     

通过外加应变于高双折射环镜实现掺铒光纤激光器的输出功率控制

本文提出一种基于外加应力于高双折射环镜的输出功率可调控的掺铒光纤激光器新颖结构。通过将高双折射光纤环镜中的部分双折射光纤粘贴于一个等强度梁的中性面上，在梁尾端作用不同的应力，由于双折射光纤的长度和双折射的改变可使环镜的反射率从0.8%变化到100%。以该环镜作为线形腔光纤激光器的输出腔镜，实现了动态范围达33dB的输出功率可调控的掺铒光纤激光器。该激光器不仅具有结构简单、成本低廉的优点，而且利用该机理可以很容易的找出最优腔镜反射率，从而使线形腔光纤激光器的输出性能实现最优化。     

Wavelength tunable erbium-doped fiber ring laser operating in L-band

We describe a novel erbium-doped fiber ring laser utilizing the backward amplified spontaneous emission (ASE) power as a secondary pump source so that it can operate in L-band stably. The output wavelength can be tuned in a wide range of 45 nm, from 1560 to 1605 nm. We also compared this scheme with the condition of not using the ASE as secondary pump source, and found this scheme could improve the performance of the laser when using the same components.