基于多模光纤滤波器的可调谐掺铒光纤激光器

研究了一种新型、全光纤、宽带可调谐环形腔掺铒光纤激光器。该激光器利用由单模-多模-单模光纤组成的滤波器实现波长可调谐及激光器的全光纤结构。该滤波器将多模光纤缠绕在偏振控制器上,两端分别与一段单模光纤相连,通过调整偏振控制器的状态,实现了中心波长1542～1560nm的不同激光输出。单波长连续可调谐激光器的波长可调范围为18nm,边模抑制比大于40dB,3dB线宽为0.096nm;进一步调整偏振控制器的状态和抽运功率,实验同时得到了连续可调谐的双波长、三波长等多波长激光输出。对于可调谐的多波长激光器,通过调整偏振控制器的状态,可实现波长间隔及输出中心波长两者可调。     

基于多模光纤滤波器的可调谐掺饵光纤激光器

研究了一种新型、全光纤、宽带可调谐环形腔掺饵光纤激光器.该激光器利用由单模-多模-单模光纤组成的滤波器实现波长可调谐及激光器的全光纤结构.该滤波器将多模光纤缠绕在偏振控制器上,两端分别与一段单模光纤相连,通过调整偏振控制器的状态,实现了中心波长1542～1560 nm的不同激光输出.单波长连续可调谐激光器的波长可调范围...     

一种新型自激发布里渊掺铒光纤激光器

利用级联的受激布里渊效应,自激发布里渊掺铒光纤激光器可以实现常温下的多波长激光输出。通过在自激发掺铒光纤激光器中引入一个高双折射萨尼亚克(Sagnac)环形滤波器,调节萨尼亚克环形滤波器的偏振控制器(PC),实现了可调谐多波长输出,同时在实验中观测到双布里渊多波长带的现象。研究了这种光纤激光器中萨尼亚克环形滤波器的带宽和980 nm抽运光功率对输出波长数的影响,在萨尼亚克环形滤波器的带宽为83.3 nm以及980 nm抽运光功率为260 mW时,得到了52个间隔为0.088 nm的多波长激光输出。     

基于高双折射光子晶体光纤与光纤环的超宽带可调谐微波光子滤波器

提出一种基于高双折射光子晶体光纤与光纤环的超宽带可调谐微波光子滤波器.以多波长光纤激光器作为光源,向高双折射光子晶体光纤内填充温敏液体,通过改变填充温敏液体的温度,高双折射光子晶体光纤可具有不同的双折射,得到不同波长间隔的激光,从而使微波光子滤波器具有不同的自由频谱范围.当温度的变化范围为20~80℃时,仿真测得微波光子滤波器自由频谱的变化范围为2.49~39.9GHz.引入光纤环构建级联型微波光子滤波器,滤波器的主旁瓣抑制比可提高到33.6dB,Q值可达到499,提高了滤波器的频率选择性.     

基于光纤中超短脉冲非线性传输机理与特定光谱选择技术的多波长飞秒激光的产生

高集成、高可靠性宽调谐飞秒激光源在超快光谱学、量子光学及生物成像等研究与应用领域具有重要价值.如在生物多光子显微成像中,具有适中能量的宽调谐飞秒激光源不仅可满足多种生物组织荧光激发所需的峰值功率与激发波长,而且也可以显著提升非线性荧光产生效率、成像分辨率以及增大成像穿透深度.采用自主研发的高可靠性全保偏光纤飞秒激光器作为抽运源,基于低色散光纤中高峰值功率飞秒激光脉冲非线性传输引起的光谱加宽机制,本文开展了多波长全光纤飞秒激光产生技术研究.通过采用中心波长在980, 1000,1050, 1070与1100 nm的带通滤波片选择性地对单模光纤输出光谱中最左边与最右边光谱旁瓣进行滤波,在上述中心波长处分别可获得203, 195, 196, 187与194 fs的激光输出.本文提出的基于全光纤飞秒激光脉冲在单模光纤中非线性传输引起的光谱加宽机制与特定光谱选择技术的实验方案为高集成、高可靠性宽调谐飞秒激光源的实现提供了新的研究途径.     

2μm波段双波长间隔可调谐光纤激光器

提出并实验研究了一种2μm波段全光纤间隔可调双波长光纤激光器.该激光器采用传统的环形腔设计,以最大输出功率33dBm的1 565nm光纤激光器为泵浦源,4m单模掺铥光纤为增益介质,腔内为嵌入多模干涉滤波器的Sagnac环的复合滤波结构.该复合滤波器可实现间隔可调谐,高边模抑制比的双波长激光信号输出.通过泵浦功率的控制和对复合滤波器中偏振控制器的调节,实现双波长3nm到80nm间隔可调的激光输出,边模抑制比为60dB,线宽为0.2nm,功率稳定度为±1.5dB/h,双峰能量差小于4dB.     

100nm宽光谱可调谐掺饵光纤激光器

采用1480 nm大功率激光二极管双向抽运,新型铋基掺饵光纤做增益介质,基于旋转法布里-珀罗腔的可调谐滤波器和带通滤波器做选频装置的宽光谱环形腔可调谐光纤激光器,可实现100 nm（1523~1623 nm）激光波长程控连续可调谐输出,激光输出功率大于1.58 mW,3 dB带宽小于0.1 nm,波长重复性准确度小于0.01 nm.     

锁模脉冲波长连续可调谐光纤激光器

利用在腔内加入可调谐光纤光栅滤波器使“8”字形腔掺Yb3+光纤激光器在锁模状态下实现波长连续可调谐.实验中,在保证锁模状态稳定的情况下,通过调节可调谐光纤光栅滤波器,使激光器输出锁模脉冲的中心波长在1 047 nm～1 055 nm范围内连续调谐,重复频率稳定维持在4.9 MHz.在中心波长1 053 nm处,测得锁模脉冲输出平均功率为8.02 mW,光谱带宽1 nm,脉冲宽度为259.3 ps.这种“8”字形腔被动锁模光纤激光器在锁模状态下对波长连续可调谐,并可长时间稳定工作.     

可用于产生微波信号的间隔可调双波长光纤激光器

为了获得不同间隔双波长信号输出,提出一种基于受激布里渊效应产生双波长激光的实验装置,利用不同间隔双波长输出信号进行拍频实验可获得可调的微波信号输出;利用一段10 km长普通单模光纤（SMF）作为布里渊增益介质,一个线宽为5 kHz分布反馈激光器（DFB）作为布里渊抽运源,一段未泵浦的保偏掺铒光纤用作饱和吸收体抑制边模,通过改变未泵浦保偏掺铒光纤的长度,可获得不同间隔输出的双波长光纤激光器,实验获得波长间隔为0.170 nm和0.085 nm的激光信号输出,分别对应20 GHz和10 GHz的微波信号。     

基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术

首次提出了一种基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术, 利用保偏光纤光栅选频产生两个偏振稳定的激光信号, 采用扰偏器确保激光输出的两个正交偏振态功率的一致性, 最后输入高速光电探测器产生微波/毫米波. 通过对保偏光纤光栅施加不同大小的侧向应力, 可以灵活调谐输出的毫米波频率. 实验制作了基于偏振稳定双波长保偏光纤光栅激光器的可调 谐微波/毫米波产生装置, 通过对保偏光纤光栅施加不同的轴向拉力分别产生了20.407 和22.050 GHz的微波信号. 仿真产生了60 GHz的毫米波信号, 并分析该毫米波在光纤无线通信下行链路的传输性能, 结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端, 解调后仍然得到很好的眼图, 充分证明了本方案的优越传输性能.     

High-Q microwave photonic filter with self-phase modulation spectrum broadening and third-order dispersion compensation

We propose and experimentally demonstrate a scheme of high-Q microwave photonic filter （MPF） using the techniques of self-phase modulation （SPM） spectrum broadening and third-order dispersion （TOD） compensation. The optical pulses from a mode-locking laser are spectrally broadened by the SPM in the highly nonlinear fiber. A wideband optical frequency comb with 365 spectral lines within 10-dB power variation from the highest spectral power is obtained. By applying a cubic phase modulation via a waveshaper, the effect of TOD which broadens the MPF passband is eliminated. The final implemented MPF has a Q-value as high as 296 and a tuning range of 700 MHz.     

Wideband frequency tunable optoelectronic oscillator based on a dispersion compensated microwave photonic filter

A wideband tunable optoelectronic oscillator (OEO) based on a dispersion compensated phase modulated microwave photonics filter (MPF) is proposed and experimentally demonstrated. The MPF, consisting of a tunable laser source (TLS), a phase modulator, a fiber Bragg grating Fabry–Perot filter and a photodetector, is used as the oscillating mode selection device. Dual-loop configuration is employed to make sure the OEO operates at a single oscillating mode. Theoretically analysis is carried out to demonstrate the tuning range limitation due to the phase-modulation to intensity-modulation conversion caused by long single mode fiber (SMF). To overcome this disadvantage and expand the signal tuning range, a dispersion compensation fiber is introduced followed by the SMF to compensate the fiber dispersion. By simply adjusting the wavelength of the TLS, an ultra-wideband tunable microwave signal with the frequency tuning range from 2 to 44 GHz is obtained. The phase noise is also investigated and measured to be less than ? 110 dBc/Hz at an offset of 10 kHz within the whole frequency range.     

Pulse shortening and quality improvement based on spectral filtering in a stretched-pulse mode-locked fiber laser with large third-order dispersion

We demonstrate a passively mode-locked ring fiber laser operating in the stretched-pulse regime. The ring cavity model is constructed with standard single-mode fiber and dispersion delay line for dispersion management. Here, all-solid Yb-doped photonic bandgap fiber is used as the dispersion delay line and provides laser gain simultaneously. As the all-solid Yb-doped photonic bandgap fiber has large third-order dispersion, it is necessary to study its impact on the stretched-pulse operation. The presence of the third-order dispersion reduces pulse quality because of the relatively small group velocity dispersion. To improve the pulse quality, a spectral filter is employed in the model. The simulation results show that spectral filtering could improve the pulse quality and shorten the pulse duration. Meanwhile, the optimum filter bandwidth is studied.     

介质膜滤波器色散特性的研究

采用信号处理的方法,对介质膜滤波器的滤波特性进行了详细的研究。介质膜滤波器是最小相位滤波器,它的幅度响应与相位响应之间存在希尔伯特变换规律,因此可以通过它的幅度响应重构它的相位响应,进而可以得到它的色散特性。为了验证理论分析,设计了射频调制法测试介质膜滤波器群速度延时的实验装置。实验测试了一个100GHz33信道的介质膜滤波器的群速度延迟。通过对实验结果与理论计算结果的对比分析,发现实验数据与理论分析吻合得比较好。最后,对介质膜滤波器的色散的特点进行了分析。     

高功率纳秒光脉冲在单模光纤中的受激喇曼散射及抑制研究

利用包含喇曼增益、抽运消耗、自相位调制、交叉相位调制和群速度色散效应的耦合非线性薛定谔方程组,对千瓦级高功率纳秒脉冲在单模光纤中的传输特性进行了模拟计算.分析了输入脉冲和斯托克斯脉冲的演化过程,研究了大模面积光纤对受激喇曼散射的抑制作用.研究结果表明,采用模面积为530 μm~2的光子晶体光纤作为惯性约束聚变脉冲整形系统的传输介质,能有效抑制受激拉曼散射,不但信号衰减较小,而且中心凹陷程度较低.     

一种改进的双边带调制产生光毫米波的方案

提出了应用于光纤无线通信系统中一种改进的双边带调制产生光毫米波方案。在中心站采用强度调制将射频信号调制到光载波上产生一个双边带信号,滤掉中心载波后,利用光交叉复用器把双边带信号的上下边带模分开,将数据速率为2.5Gbit/s的基带信号调制到下边带模后,再与未调信号耦合后产生光毫米波,然后通过单模光纤传输至基站,在基站经过光电转换后产生电毫米波信号。从理论上对该毫米波的色散特性进行了分析,发现毫米波的接收功率不会周期的衰减。同时通过实验研究表明,下行链路信号通过光纤能传输50km而不需要色散补偿,功率代价小于1dBm。因此,该方法产生的光毫米波能有效克服光纤色散引起的信号时延而导致的基带信号退化,适合于远距离传输。     

Widely tunable ring-cavity tellurite fiber Raman laser

We report a widely tunable ring-cavity tellurite fiber Raman laser covering the S+C+L+U band. A tunable range (1495-1600 nm, limited by the tunable optical bandpass filter) over 100 nm is obtained by using a single-mode tellurite fiber with high Raman gain coefficients (55 W(-1)km(-1)) and large Raman shift (~22.3 THz) as the gain medium. Furthermore, the free-running 1665 nm Raman fiber laser is achieved from the ring cavity by removing the tunable optical bandpass filter, which shows that such a tellurite fiber has potential for constructing a widely tunable fiber Raman laser covering the S+C+L+U band. A high optical signal-to-noise ratio of over 60 dB for almost all of the tunable range is also demonstrated.     

Photonic generation of a microwave signal by employing a microfiber ring resonator

A novel approach to generate microwave signals is presented by employing a microfiber ring resonator. The microfiber ring resonator is assembled with a microfiber fabricated by heating and drawing standard single-mode fiber. By cascading microfiber ring resonator acted as a comb filter with a tunable bandpass filter, a wavelength-tunable dual-wavelength single longitudinal-mode laser is achieved. A microwave signal at 15.57 GHz with the linewidth of less than 21 kHz is demonstrated by beating the two wavelengths at a photodetector.     

基于串行最小频移键控的8进制调制的研究

提出了一种新型的基于串行结构的最小频移键控调制技术,产生了相位连续,频谱宽度窄,每码元时间有两次π/2相移,类似于传统最小频移键控调制信号,给出了该调制方案的理论推导,并将其应用于8进制的多维多阶调制系统中。理论和仿真分析了不同的8进制调制方案在频谱特性,残留色散容限,自相位调制容限的不同,还分析了其受到系统滤波带宽的影响。最后仿真实现了通过350km的色散完全补偿的光纤120Gb/s的数据传输。