基于可调谐真相移的可调谐光电振荡器

提出一种基于真相移(TPS)实现可调谐光电振荡器( OEO)的方案。只需通过调谐Mach-Zehnder 调制器(MZM)的偏置电压,就可以实现可谐滤波器的频谱响应的改变,即可实现TPS滤波器。 其中,两个抽头的可调谐滤波器是由双光源、双调制器以及叠印光栅来实现。OEO的输出频 率由二抽头可调 谐滤波器的峰值频率决定,而滤波器可调谐,这样就可以实现输出OEO的输出频率可调。 仿真结果表明,输出频率可以实现5～10GHz宽带宽可调谐。     

基于可变激光源和啁啾M-Z调制器的双调谐光电振荡器

设计了一种利用微波光子滤波器(MPF)实现频率可调谐的光电振荡器(OEO)。该模型通过双驱动Mach-Zehnder调制器(DD-MZM)和啁啾光栅形成高Q值的MPF,得出OEO的振荡频率是关于光源波长和DD-MZM直流偏置电压的函数,通过对光源波长或DD-MZM偏置电压的调整,可实现振荡频率调谐功能。同时,在电域上,利用RF耦合器和RF延时线形成两路具有延时差的反馈信号,通过合并后反馈至DD-MZM,从而有效地抑制边模。理论和仿真实验表明,针对不同的调谐范围可实现粗调和微调的功能。     

高功率、宽调谐掺Tm光纤主振荡功率放大器

输出波长位于2μm附近的可调谐掺Tm激光器在光通信、激光雷达、环境监测等领域都有广泛的应用。介绍了基于主振荡功率放大(MOPA)方式的高功率、宽调谐掺Tm光纤放大器的实验研究。其中,主振荡系统采用闪耀光栅的Littrow衍射提供外腔反馈和波长选择,实现了调谐范围超过160nm(1921～2084nm)的低功率激光输出。为提高该激光器的输出功率,采用MOPA方式对其进行一级放大,实现了高功率、宽调谐激光输出。调谐范围大于140nm(1936～2081nm),且在大于100nm(1962～2066nm)范围内输出功率均超过54W。在中心波长1981nm处,获得功率为77.4W,斜率效率为34.4%的高功率激光输出。     

基于悬臂梁啁啾调谐的光纤光栅滤波器

提出并发展了一种基于悬臂梁结构的啁啾光纤Bragg光栅(CFBG)啁啾调谐方案,获得了一系列性能优异的可调谐CFBG滤波器,包括调谐范围达到36 nm(1.8～37.8 nm)的带宽可变反射滤波器、色散在178～2 100ps/nm范围内可调的色散补偿器、基于取样CFBG或重叠写入CFBG的信道间隔可调谐滤波器等。这些FBG滤波器不但能维持较高的反射率,还能保持中心波长基本不变。     

精细调谐电增益环腔光电振荡器

为了有效实现光电振荡器(OEO)输出频率精细调谐 ,提出了一种基于电增益环腔(EGRR)的OEO。利用放大器、 滤波器和移相器构成可调谐EGRR,通过改变EGRR内信号的相位等效实现 环腔长度的改变,得到不同 频率的射频(RF)信号,RF信号与OEO产生的自由振荡信号电注入锁定,输出信号 的频率由锁定EGRR输出频 率的OEO模式决定,相位噪声由OEO决定。在简单结构实验的条件下,有 效实现了OEO输出频率精细调谐。实验结果表明,当光纤长为2km、EGRR长为0.5m时,得到 了频率为11.3GHz、边模抑制比(SMSR)为 48dB、可调谐范围为239MHz、调谐最小步长 为100kHz和相位噪声为－99dBc/Hz@10kHz的RF信号。     

宽带可调谐光纤光栅色散补偿器系统设计

文章提出一种在光纤光栅自身热膨胀效应产生啁啾的基础上,利用铝片热膨胀系数比较高的特点产生应力来增强光纤光栅啁啾,从而实现了宽带、大范围色散调谐的新型光纤光栅色散补偿器。该色散补偿器能够分别对群速度色散及中心波长独立调谐。实验结果表明,在中心波长为1 551.25nm处,能够实现>1.5nm的色散补偿带宽,-350～-690ps/nm的群时延色散调谐范围;在色散为-660ps/nm情况下,能够实现中心波长1nm的偏移。     

基于激光外调制的频率可调谐光电振荡器

为了实现光电振荡器(OEO)输出频率的可调谐,提出了一种基于外调制激光的频率可调谐光电振荡器。此方案在单环OEO的基础上增加一个由微波滤波器、电衰减器、电放大器和电移相器构成的电增益选频腔,通过调节电移相器的偏置电压可以等效改变电选频腔的腔长,从而改变其输出微波信号的频率;同时调节光延时线来改变光电振荡器的起振模式,通过电增益选频腔信号与光电振荡器自由振荡信号的电注入锁定,即可实现频率可调谐的光电振荡器,其输出信号的频率由锁定OEO模式的电增益选频腔决定。实验结果表明,本方案产生了频率调谐范围为10.05 GHz~10.09 GHz、调谐步长为400 kHz的输出信号,频率在40 MHz的范围内连续可调谐。在输出频率为10.0519 GHz时,其边模抑制比为60 dB,相位噪声为-115 dBc/Hz @10 kHz。该方案结构简单,既保留了单环OEO低相位噪声的优势,又能有效抑制边模,为实现频率可调谐OEO提供了一种新的方法。     

高功率中红外宽调谐全固态周期性极化铌酸锂光参量振荡器

中红外宽调谐激光器在激光光谱、拉曼光谱和大气污染探测、环保检测等领域有很多应用。目前主要采用光参量振荡 (OPO)输出中红外激光。本实验采用主动调Q的全固态Nd∶YVO4 激光器 ,输出波长为 1 0 6 4nm的准连续激光抽运周期性极化铌酸锂 (PPLN)晶体 ,实现OPO中红外激光输出。激光波长调谐范围为 2 90～ 4 0 5 μm ,最高输出功率为 2 76mW ,实验中同时输出波长范围为 1 4 4～1 6 6 μm的近红外激光。实验装置采用外腔OPO(见图 1 ) ,其抽运光源为LD抽运的Nd∶YVO4 激光器 ,输出重复频率为1 6 2kHz ,脉宽为 2 0 5ns ,平均功…     

基于载波相移双边带调制的可调谐光电振荡器

设计了一种利用载波相移双边带调制(CPS-DSB)系统实现宽带频率可调谐的光电振荡器(OEO)。其中CPS-DSB系统由3dB耦合器、π偏置Mach-Zehnder调制器(MZM)及可变移相器(VPS)组成,并与线性啁啾光纤Bragg光栅(LCFBG)完成可调谐微波光子滤波器(MPF)的功能。通过调整VPS的相位可完成MPF中心频率的调谐,进而实现OEO振荡频率的调谐功能。理论分析和仿真实验表明,通过调谐VPS的相位可实现振荡频率大范围调谐。     

温控FBG式4通道波长可调准OADM研究

实现了一种带温度控制的基于FBG的4通道波长可调准光分插复用器(OADMs)。对用悬臂粱法调谐的FBG中心波长温度稳定性进行了研究,设计了一种灵巧的温度控制装置,解决了FBG中心波长可调谐和温度稳定性间的矛盾。测试结果表明,实现的OADMs在环境温度范围-20℃～ 60℃,中心波长变化小于0．004nm／℃,与未经温度补偿的悬臂梁调谐光栅相比温度稳定性提高了6．75倍。利用悬臂梁方法实现了FBC;中心波长的微调,调谐范围为1nm。4路OADMs的信道间隔为0．8m,上下路3dB通道带宽小于0．3nm,符合ITU-TG．692的要求。利用自制的FBG实现OADMs的邻道隔离度大于35dB。     

具有32 GHz频差的掺Yb3+双频DBR光纤激光器

基于自制的双波长低反射率光纤光栅（FBG）作为分布式布拉格反射激光器（DBR）的输出端,实现了掺Yb3+双频DBR光纤激光器。该FBG的双波长间隔为0.12 nm,对应的频差为32 GHz。双频光纤激光器输出的两个波长分别为1 063.09 nm和1 063.21 nm,光谱信噪比大于60 dB。每一个波长只包含一个纵模。两个纵模的拍频信号为32.014 GHz,频谱信噪比大于35 dB。得益于光纤激光器本身具有结构紧凑,抗干扰能力强等特点,该型激光器有望作为高品质,小型化的微波信号源,用于微波传感和通信等领域。     

Tunable wavelength converters of picosecond pulses based on periodically poled LiNbO3 waveguides

A tunable wavelength conversion between picosecond pulses is experimentally demonstrated by using cascaded sum- and difference-frequency generation (cSFG/DFG) in a periodically poled LiNbO3 (PPLN)waveguide. The pulsed signal with 40 GHz repetition rate and 1.57 ps pulse width is adopted. When the input signal and the first control wavelengths are kept at 1554.2 and 1532.5 nm, respectively, the output signal wavelength can be tuned from 1536.0 to 1545.2 nm as the second control wavelength varies from 1550.5 to 1541.0 nm. By varying the first control wavelength to satisfy the quasi-phase matching (QPM) condition for sum-frequency generation (SFG) and simultaneously adjusting the second control wavelength, the tunable output signal wavelength can also be obtained when the input signal wavelength is changed. In the experiment,the amplified spontaneous emission (ASE) noise from the erbium-doped fiber amplifier (EDFA) is effectively suppressed by employing two narrow band tunable filters. Therefore, the wavelength down- and up-conversions are simultaneously observed.     

Microwave photonic bandpass filter based on spectrumslicing and phase modulator

A tunable microwave photonic bandpass filter with high mainlobe-to-sidelobe ratio (MSR) based on a phase modulator and a dispersive device is proposed. The multi-tap characteristics of the filter are realized by slicing a broadband source using a Mach-Zehnder interferometer (MZI) which results in a high MSR of 25 dB. The tunability of the filter is realized by an optical variable delay line (OVDL) in one arm of the MZI, which changes the wavelength spacing of the sliced broadband source and results in a tunable free spectrum range (FSR) of the filter. The central frequency of the bandpass filter is tunable from 10.7 GHz to 27 GHz by changing the wavelength spacing from 0.145 nm to 0.054 nm.     

Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating

We present the design and development of a novel tunable dispersion compensator with fixed center wavelength that is based on the electrical adjustment of the chirp of a fiber Bragg grating (FBG). Both temperature gradient and strain gradient are employed to adjust the chirp of the FBG jointly. The electrical current flowing through the taper on-fiber thin-film heater will introduce a temperature gradient on the FBG. The shrinkage of a negative thermal expansion coefficient (NTEC) ceramic due to the temperature rise will compress the tapered FBG mounted inside it, and this will introduce a strain gradient on the FBG. The center wavelength of the FBG will be kept fixed because the effect of temperature rise on the FBG and the effect of compression of the FBG will offset each other. Applying an electrical power of less than 0.68 W, we demonstrate a linearly chirped FBG whose dispersion can be continuously adjusted from -178 ps/nm to -302 ps/nm with a central wavelength shift of as small as 0.16 nm.     

Continuously wavelength-tunable MQW fabry-perot laser diode pulse source with a fiber-based external cavity

A simple continuously wavelength-tunable fiber ring laser pulse source is demonstrated. Such a source employs a gain-switched multiple quantum-well Fabry-Perot laser diode in a self-seeding scheme and the output pulse wavelength can be tuned continuously via a tunable optical filter. The optical pulses generated exhibit a pulsewidth of 92 ps at the frequency of 2.6 GHz. Within a wide wavelength tuning range of 46 nm, the side-mode suppression ratio and the average power of the output optical pulses obtained are higher than 50.1 dB and 3.3 dBm, respectively, and the pulse spectral stability can be maintained in the whole wavelength tuning range.     

10 GHz再生锁模光纤激光器获得光纤超连续谱的研究

报道了利用10GHz再生锁模光纤环形激光器（RML-FRL）获得波长在1528～1563nm连续可调、脉宽为4．6～5．8ps的短脉冲输出作为高稳定的光纤超连续（SC）谱泵浦源。对RML-FRL输出的脉冲直接放大泵浦4．5km色散位移光纤（DSF），得到20dB带宽46．08nm的SC谱输出，经阵列波导光栅（AWG）谱切片后，得到间隔100GHz、中心波长符合ITUT标准的30信道输出，脉宽在6．5～7．8ps，示波器显示任意信道的抖动均值小于1．4ps。     

Miniature packaged actively mode-locked semiconductor laser with tunable 20 ps transform limited pulses

Miniature, fibre tailed and packaged, wavelength tunable actively mode locked semiconductor lasers have been developed for use as sources of approximately 20 ps transform limited pulses. Continuous stable operation with >40 nm tuning ranges centred either at 1.3 mu m or 1.55 mu m have been demonstrated. The package has an adjustable cavity length enabling the repetition frequency to be selected between 2 GHz and 8 GHz. Mean output powers in the monomode fibre tail are in the range -10 dBm to -5 dBm.<>     

基于均匀光纤光栅的DWDM系统PMD补偿方法

提出一种基于均匀光纤Bragg光栅(FBG)的透射型密集波分复用(DWDM)系统多信道偏振模色散(PMD)补偿方案。当FBG受到横向挤压时，会产生双折射现象。当一波长的光信号从光栅带隙附近透射时，就会在快轴和慢轴之间产生时延差(DGD)。通过改变外力的大小来调节DGD的大小可以实现对PMD的补偿。通过将多个补偿光栅级联，就可以实现对DWDM系统多信道PMD的补偿。在100N外力作用下，5cm长的光栅最大可以补偿121ps的PMD，而对相邻0．8nm的信道，只引入0．2ps的DGD。     

A widely tunable fiber ring laser with closed loop control based on high-precision stepper motor

A tunable single-longitudinal mode erbium-doped fiber ring laser based on stepper motor and closed loop control is proposed and demonstrated. The system consists of an erbium-doped fiber (EDF), a tunable fiber Bragg grating (FBG) filter and a wavelength detector. The characteristics of output laser, such as output power, power stability and 3-dB linewidth, are investigated in the operation range of 1 531—1 569 nm. The repeated experimental results of the fiber laser show that the 3-dB linewidth is less than 17 ps, the side-mode suppression ratio (SMSR) is up to 60 dB, the output power is up to 1.37 dBm, and the power variation is less than 0.61 dB.     

Frequency and wavelength tunable optical microwave source based on a distributed Bragg reflector self-pulsation laser

A frequency and wavelength tunable self-pulsation laser based on DBR laser devices is reported for the first time.This laser generates continuous tunable optical microwave in the range of 1.87-21.81 GHz with 3-dB linewidth about 10 MHz by tuning the injection currents on the front and back gain sections,and exhibits wavelength tuning range from 1536.28 to 1538.73 nm by tuning the injection currents on the grating section.