C波段色散补偿光子晶体光纤的研究和设计

设计了一种新颖结构的双层芯色散补偿光子晶体光纤。此光纤在整个C波段具有高负色散特性。通过合理选取双层芯光纤的外层芯层数,同时优化孔间距和空气孔直径,设计的光纤在C波段的色散值在-520ps/(km.nm)和-390ps/(km.nm)之间近似线性变化,残余有效色散系数近似为零,相关色散斜率(RDS)在0.0032nm-1的色散补偿光纤,其RDS值与标准单模光纤匹配,有效模场面积优于常规色散补偿光纤,可以对其长度30倍以上、用于宽带传输的标准单模光纤进行良好的色散和色散斜率补偿。     

宽带色散补偿光子晶体光纤的优化设计

设计了一种宽带色散补偿光子晶体光纤,此光子晶体光纤在整个C波段具有较大的负色散值,且其色散斜率值均为负值。通过合理选取光子晶体光纤的层数和孔间距,同时优化各层的空气孔直径大小,分别设计了在1 550nm附近的色散值为-425、-440和-400ps.km-1.nm-1;且色散斜率分别为-1.49、-4.31和-8.59ps.km-1.nm-2的宽带色散补偿光子晶体光纤。可以分别实现与G.652和G.655光纤的卡帕值和相对色散斜率相匹配,具有较好的宽带色散补偿能力。     

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FDTD方法的光子晶体光纤色散特性分析

基于电磁场时域有限差分法(FDTD)计算光子晶体光纤(PCF)的方法, 分析了运用该方法时需要注意的一些问题, 特别是关于晶格位置、晶格上各个电磁场分量的分布以及完全匹配层(PML)中在边界处的电磁场的处理。以此为理论依据分析了一种纯石英材料双层芯PCF, 对这种光纤的传输特性进行了详细的数值模拟。通过调整光纤的结构参数, 设计出大负色散值的宽带色散补偿光子晶体光纤(DCPCF)。数值模拟结果显示在1530～1565 nm波长范围内其色散值在-400和-600 ps/(km·nm)之间变化, 达到了具有相同有效模面积的普通色散补偿光纤(DCF)的5倍。在整个C波段可以有效补偿长度25倍以上的标准单模光纤(SMF), 其色散剩余量在±1.0 ps/nm·km以内。该种结构的PCF对于制作高增益和宽带色散补偿于一体的集中式光纤放大器具有十分重要的意义。     

用于10Gb／s WDM系统色散补偿的波长取样啁啾光纤光栅

研制出一种新型色散补偿光纤光栅--波长取样啁啾光纤光栅,它具有10个周期性为0.8nm的波长结构,每个周期的反射特性和色散特性都基本相同,其带宽为0.6nm、峰值反射率为90%、色散量为1300ps/nm、时延抖动小于50ps,光栅长度为10cm.利用此波长取样啁啾光纤光栅,在8×10Gb/s波分复用(WDM)系统中,进行了NRZ码140km标准单模光纤的色散补偿实验,补偿效果良好.     

八角格子色散补偿光纤

为了消除光纤通信系统中色散,采用各向异性完全匹配层和全矢量有限元方法,进行了理论分析和实验验证,设计了一种基于八角格子晶体的同轴双芯色散补偿光子晶体光纤;得到了该色散补偿光纤的传输特性如基模有效折射率、色散、损耗和非线性系数方面的数据,并分析了光纤波导色散与色散补偿光纤结构参量之间的关系。结果表明,所设计的光纤在200nm的负色散范围内,拥有负色散值(在波长为1.55m处有最低负色散值-1500 ps/(nmkm)),同时在E+S+C波段有较低的限制损耗(小于3.3dB/km);非线性效应也得到显著抑制。     

基于光子晶体光纤的宽带色散补偿光纤的设计

采用矢量光束传输法(VBPM)对小纤芯光子晶体光纤(PCF)的色散特性进行了数值分析,研究发现通过调节光子晶体光纤的结构参数可以灵活的对其色散补偿值进行调整,能够实现C L波段(1 530～1 565 nm)的宽带色散补偿功能,并且对标准单模光纤的色散斜率有很好的补偿.在∧=1.0μm,d/∧=0.7时,1 550 nm处的色散值可以达到-339.1 ps/(km×nm),相关色散斜率(RDS)可以达到0.003 2 nm-1,能够有效的对标准单模光纤进行色散斜率补偿.     

C+L波段色散补偿光纤及模块的研制

波分复用(WDM)传输系统工作波段已经覆盖了C波段和L波段．工作在C L波段的色散补偿模块及色散补偿光纤的研制是通信器件开发的一个重要领域．文章分析了C L波段色散补偿光纤的波导结构,并采用PCVD工艺研制成功了C L波段色散补偿光纤,该光纤可以同时对工作在C和L波段的通信系统的色散进行补偿。     

双芯准晶格光子晶体光纤的色散特性

设计了一种折射率引导型双芯准晶格光子晶体光纤,并基于有限元法对其色散特性进行数值模拟和研究。该光纤内、外纤芯中光波的耦合效应,可在相位匹配波长附近产生相当高的负色散值。通过分析内包层孔径d1,外纤芯孔径d2,外包层孔径d3,孔间距Λ以及内包层空气孔层数的改变对光纤色散特性的影响,最终设计出一种在1550 nm低损耗窗口性能优越的色散补偿光纤,负色散峰值为-2250 ps/(nm.km),半峰全宽超过280 nm,色散-带宽乘积可达630 GHz-1.km-1。此种光纤适合在长距离高速光纤通信系统中为常规单模光纤提供色散补偿。     

利用光子晶体光纤实现10 Gb/s光传输系统的色散补偿

利用光子晶体光纤（PCF）在10Gb/s光传输系统中对普通单模光纤中传输的光脉冲进行了色散补偿，获得了很好的补偿效果。实验中，10Gb／s光脉冲序列经过2.163km普通单模光纤被展宽后．利用26m长光子晶体光纤对其进行色散补偿．补偿后脉冲基本恢复到了初始形状。进一步的理论计算表明，此光纤在C波段20nm波长范围内对普通单模光纤能够实现较好的色散斜率补偿，补偿后剩余色散小于5ps／nm。理论与实验结果表明光子晶体光纤在色散补偿方面具有很大的潜力．在未来光通信系统中将发挥重要作用。     

基于SOA啁啾管理的连续可调谐色度色散补偿的研究

提出了一种新型的可小范围连续调谐的色度色散(CD)补偿方案.该CD补偿方案包括一个半导体光放大器(SOA)和一段固定长度的色散补偿光纤(DCF).利用SOA的交叉相位调制(XPM)效应,通过调节SOA的偏置电流和控制脉冲光的强度,可以对进入SOA的光信号引入不同大小的附加啁啾量,从而可以利用固定长度的DCF得到补偿后的无啁啾光信号.实验中,实现了10 Gb/s可调谐CD补偿器,在无需替换DCF的情况下,实现了补偿范围为-40 ps/nm到60 ps/nm的连续可调谐CD补偿.     

Dispersion flattened transmission line consisting of wide-band non-zero dispersion shifted fiber and dispersion compensating fiber module

The transmission line consisting of non-zero dispersion shifted fibers (NZ–DSFs) and dispersion compensating fiber (DCF) modules has been proposed to enable the wide-band wavelength division multiplexing (WDM) transmission. The NZ–DSFs with the effective area over 60 μm² and the dispersion of +5–11 ps/nm/km (1500–1600 nm) have been developed to suppress the transmission penalty caused by the four-wave mixing. The DCF modules which compensate for the dispersion and the dispersion slope simultaneously have also been realized. To enhance the figure of merit (FOM) of the DCF by enlarging the absolute value of its dispersion is found to be an effective way to reduce the non-linear effects occuring in the DCF. The transmission line actually fabricated based on the optimized design exhibits an extremely low dispersion deviation of ±0.08 ps/nm/km in the C band.     

Dispersion-compensation module based on one preform design matching arbitrary dispersion and slope requirements

In this article, we propose a method to realize dispersion-compensation modules (DCMs) with a user-defined dispersion in a specified bandwidth for a given tolerance. It is based on the wavelength shift of a characteristic dispersion function by scaling the refractive-index profile. Controlling the fiber diameter during the manufacturing process leads to the desired scaling. In order to get a DCM with the predefined wavelength-dependent dispersion, a specific diameter-versus-position function has to be implemented. To demonstrate the concept, compensators for typical transmission fibers were simulated. For example, the dispersion in the complete C band (1530-1570 nm) can be compensated for 100 km of TeraLight and TrueWave-RS. The results showed a residual dispersion of only /spl plusmn/1 ps/nm and could be realized with overall compensator lengths of 3.54 and 1.97 km, respectively. Furthermore, higher order dispersion in the S, C, and L bands (1490-1610 nm) was compensated for different requirements with a tolerance of only /spl plusmn/0.5 ps/nm, which enables ultrahigh bit-rate transmission at 160 Gb/s. In order to estimate the feasibility of such a DCM, a tolerance analysis is presented, and the guiding properties are approximated.     

Dispersion-compensator incorporated optical fiber amplifier

An optical fiber amplifier incorporating a dispersion compensator such as a dispersion compensating fiber (DCF) is proposed and examined theoretically and experimentally. The new amplifier requires only a single pump laser. In the experiment a 0.98-μm laser diode was used and the pump power was 50 mW. By utilizing remnant pump power, the amplifier can halve the loss effect of the compensator and double the apparent figure of merit of the DCF (ps/nm/dB). The noise figure of the new amplifier is not affected by inserting the DCP. A low-noise figure of 5 dB was obtained over a wide input-power range of -40 to -10 dBm     

Second- and third-order dispersion compensator using ahigh-resolution arrayed-waveguide grating

We have proposed a dispersion compensation scheme that uses a high-resolution arrayed-waveguide grating (AWG). When the diffraction order of the AWG is 59 and the number of waveguides in an arrayed-waveguide is 340, the calculated maximum second- and third-order dispersion compensation range is 18.0 ps/nm and ±6.0 ps/nm² , and 1100 ps/nm and ±937.5 ps/nm², for a 1 ps-pulse and a 12.5 ps-pulse, respectively. In experiments, second-order dispersion (-0.8 to +5.2 ps/nm) is effectively compensated for 1,1-ps pulses; and. Pulse compression by third-order dispersion compensation is successfully demonstrated     

Broad-band dynamic dispersion compensation in nonlinear fiber-based device

In this paper we report on the design, numerical simulation and experimental testing of a novel dynamic dispersion compensation device based on self-phase modulation (SPM) in nonlinear fiber. The proposed all-fiber device is inherently simple and presents several unique advantages, most notably the potential for a broad-band operation covering all wave-length division multiplexing (WDM) channels of a system and the ability to address variable amounts of residual dispersion in each individual channel. Dynamic compensation ranges of up to 140 ps/nm for a single-stage and 240 ps/nm for a two-stage device are demonstrated with 40 Gb/s CS-RZ signal. It is shown that the device can operate with a minimum channel spacing of 200 GHz. For a two-stage device with inter-stage spectral filtering, simultaneous dynamic dispersion compensation (130 ps/nm for 1 dB penalty) and 2R regeneration (2 dB receiver sensitivity improvement) are demonstrated.     

S波段分布式光纤拉曼放大器的实验研究

在S波段对3种不同配置的色散补偿型分布式光纤拉曼放大器(FRA)进行了研制。实验证明：5km DCF-50km G652光纤色散补偿型分布式FRA的增益和噪声特性优于50km、G652-5km DCF光纤和25km G652-5km DCF-25km G652光纤色散补偿型分布式FRA。测量了5km DCF-50km G652光纤色散补偿型分布式FRA的增益光谱和噪声谱。存DWDM光纤传输系统中,色散补偿分布式FRA对S波段1520nm光谱波段2个光谱间隔为0．262nm(频率间隔为34．1GHz)信号信道光谱的传输特性优于50km G652正色散FRA和5km DCF负色散FRA。     

Tunable Optical Delay Using Four-Wave Mixing in a 35-cm Highly Nonlinear Bismuth-Oxide Fiber and Group Velocity Dispersion

In this paper, an optically controlled tunable delay scheme has been proposed using four-wave mixing (FWM) wavelength conversion in a 35-cm highly nonlinear bismuth-oxide fiber (Bi-NLF) together with group velocity dispersion (GVD) in a chirped fiber Bragg grating (CFBG). The Bi-NLF offers a very large nonlinearity and gives rise to significant FWM over a short fiber segment. With the use of a CFBG, a delay range over 185 ps has been experimentally demonstrated. To investigate the performance of the tunable delay, we have applied the scheme for variable delays of 10-Gb/s amplitude-shift keying (ASK) and differential phase-shift keying (DPSK) data signals. The bit error rate (BER) measurements show a power penalty of less than 3.5 dB for both amplitude- and phase-modulated data formats. To further increase the delay time, the CFBG has been replaced by a dispersion compensated fiber (DCF) that provides a wider bandwidth of operation. A variable delay up to 840 ps has been obtained using dual-pump FWM that offers a conversion bandwidth of about 40 nm. The large conversion range helps to minimize GVD-induced pulse distortion as a shorter DCF can be used for a given delay. The Bi-NLF provides an enhanced stimulated Brillouin scattering (SBS) threshold, a reduced latency, and an increased compactness of the approach for practical applications.     

Simulation and design for a tunable dispersion compensator package

A novel optical model for a tunable dispersion compensator is realized by a deliberate packaging scheme ensuing from intensive interactions of mechanical design, materials science and numerical simulation techniques including computational fluid dynamics and finite element analysis. The compensator is comprised of multiple cascaded single cavity Gires-Tournois etalons, each under independent temperature control. Three critical issues are addressed: etalon temperature uniformity, thermal insulation and optical surface deformation of the etalons. With etalon optical surface deformation minimized and etalon temperature uniformity successfully controlled within a range of /spl plusmn/0.1/spl deg/C, this small (232 /spl times/ 139 /spl times/ 16 mm) compensator achieves extremely low group delay ripple (<2.0 ps), low insertion loss ripple (<0.5 dB, insertion loss <6.3 dB), low polarization dependent loss [(PDL),<0.15 dB] and low polarization mode dispersion [(PMD),<0.7 ps]. The dispersion tuning range is from -700 ps/nm to +700 ps/nm in a dispersion passband of 0.2 nm which is sufficient for 10-Gb/s transmission. Thermal insulation design makes the tuning process take effect within 1 min at maximum power consumption 5 W.