40Gb/s光时分复用传输光纤光栅补偿色散研究

用精密扫描掩模法写入宽阻带啁啾光纤光栅,掩模板背面两端各10％长度处镀有按4阶高斯函数透过率的膜,写入的啁啾光栅的时延纹波最大值为20ps。为减少写入光纤光栅的偏振模色散,研制了新的低偏振模色散光纤光栅补偿写入法。采用补偿写入法前的平均微分群时延为9．1406 ps;采用补偿写入法后的平均微分群时延为0．1521 ps。并利用低偏振模色散光纤光栅对40Gb／s光时分复用系统在普通G．652光纤传输122km的色散进行了补偿实验,功率代价为1．5dB。     

Directly Modulated 10 Gb/s Signal Transmission over 320 km of Negative Dispersion Fiber for Regional Metro Network

We demonstrate the transmission of directly modulated 10-Gb/s WDM signals over 320 km of negative dispersion fiber (dispersion:-2.5 ps/km/nm @1550 nm) without dispersion compensation. The results indicate that a regional metro WDM network could be implemented cost-effectively by using the proposed negative dispersion fiber and direct modulated lasers.     

Optimization of NRZ Data Transmission at 10 Gbit/s over G.652 Without In-Line DFAs

Performance limits of NRZ data transmission at 10 Gbit/s over standard single mode fiber (SSMF, G.652) without the deployment of in-line erbium-doped fiber amplifiers (EDFAs) are evaluated by means of numerical simulation. The fiber system was modeled using the standard split-step Fourier algorithm for the solution of nonlinear Schroedinger equation. The effect of group velocity dispersion (GVD) compensation scheme, degree of GVD compensation of the SSMF, and input optical powers to SSMF and to the dispersion compensating fiber (DCF) have been investigated with the aim to maximize the distance between transmitter and receiver. We have found that a post-compensation scheme performs better than the pre-compensation scheme and that, by careful selection of input powers and degree of GVD compensation, it should be possible to keep the bit-error-ratio (BER) below 10 upper index = 15 for an SSMF length of 270 km.     

Optimization of NRZ Data Transmission at 10 Gbit/s over G.652 Without In-Line DFAs

Performance limits of NRZ data transmission at 10 Gbit/s over standard single mode fiber (SSMF, G.652) without the deployment of in-line erbium-doped fiber amplifiers (EDFAs) are evaluated by means of numerical simulation. The fiber system was modeled using the standard split-step Fourier algorithm for the solution of nonlinear Schroedinger equation. The effect of group velocity dispersion (GVD) compensation scheme, degree of GVD compensation of the SSMF, and input optical powers to SSMF and to the dispersion compensating fiber (DCF) have been investigated with the aim to maximize the distance between transmitter and receiver. We have found that a post-compensation scheme performs better than the pre-compensation scheme and that, by careful selection of input powers and degree of GVD compensation, it should be possible to keep the bit-error-ratio (BER) below 10 upper index = 15 for an SSMF length of 270 km.     

16×10Gb/s啁啾光纤光栅色散补偿系统性能研究

运用啁啾光纤光栅法对在G.652光纤传输的16×10 Gb/s信号实现色散补偿数值模拟和研究,分析了入纤光功率、色散斜率以及啁啾光纤光栅色散补偿带宽对系统误码率的影响,结论是:入纤光功率在8～16 dBm之间时系统的性能较好;啁啾光纤光栅的色散补偿带宽对系统的影响较大;光纤的色散斜率对系统误码率有一定的影响.     

光纤非线性效应对10 Gb/s波分复用色散补偿系统的限制

对信道间距为１００ＧＨｚ的８倍１０Ｇｂ／ｓ波分复用色散补偿系统进行了计算机仿真,分析了光纤的色散和自相位调制（ＳＰＭ）、互相位调制（ＸＰＭ）、四波混频（ＦＷＭ）等非线性效应在具有级联光放大器系统中的作用。四种色散补偿方案是：ＳＭＦ（常规单模光纤）＋ＤＣＦ１（色散斜率为正的色散补偿光纤）、ＳＭＦ＋ＤＣＦ２（色散斜率为负的色散补偿光纤）、ＴＷ１（色散为正的非零色散光纤）＋ＴＷ２（色散为负的非零色散光纤     

Characterization of Fibers in an Existing Network for High Speed System (10Gb/s or Greater) Compatibility

With OC-192 communications systems being commercially available and higher bit rate systems in development, prudent telecommunications network administrators are testing their installed fibers to determine if they can be successfully used at 10 Gb/s and higher. Together with New Brunswick Telephone (NBTel), the Fiber Optics Group at UNB have tested various installed fibers and cables in the NBTel network for their losses at wavelengths of 1244, 1310, 1550, and 1625 nm, as well as for strain and polarization mode dispersion (PMD). Weather conditions, age, place of installation, and cable types have also been considered. Aging does not seem to affect the performance of the fibers. Although most fibers are high-speed system compatible when looking at attenuation measurements, about 40% of the fibers tested would not meet the 10 Gb/s OC-192 system manufacturer's design guidelines concerning PMD.     

Characterization of Fibers in an Existing Network for High Speed System (10Gb/s or Greater) Compatibility

With OC-192 communications systems being commercially available and higher bit rate systems in development, prudent telecommunications network administrators are testing their installed fibers to determine if they can be successfully used at 10 Gb/s and higher. Together with New Brunswick Telephone (NBTel), the Fiber Optics Group at UNB have tested various installed fibers and cables in the NBTel network for their losses at wavelengths of 1244, 1310, 1550, and 1625 nm, as well as for strain and polarization mode dispersion (PMD). Weather conditions, age, place of installation, and cable types have also been considered. Aging does not seem to affect the performance of the fibers. Although most fibers are high-speed system compatible when looking at attenuation measurements, about 40% of the fibers tested would not meet the 10 Gb/s OC-192 system manufacturer's design guidelines concerning PMD.     

8 × 10-Gb/s transmission system over 1500 km on G.652 fiber dispersion compensated by chirped fiber gratings

A low cost 8 × 10-Gb/s transmission system over 1500 km on conventional fiber using chirped fiber Bragg grating (CFBG) as dispersion compensator is demonstrated. The bit error rate (BER) below 10-10 at 1500 km is obtained. The channel spacing is 0.8 nm and the optical amplifier spacing is 100 km. Only 16 erbium-doped fiber amplifiers (EDFAs) are used.     

Performance enhancement of 10 Gb/s direct modulation optical OFDM by external optical injection

We show experimentally and by simulation a performance enhancement of a directly modulated 10 Gb/s optical Orthogonal Frequency Division Multiplexing (OFDM) system due to external optical injection. The experiment is performed back to back and over 12 km of single mode fiber. The injection extends the range of linear operation of the laser and therefore extends the usable bandwidth for direct modulation formats which are susceptible to nonlinearity, such as OFDM. Nonlinearity in the system and its reduction due to injection are estimated by means of a two tone test. Additionally the performance enhancement on OFDM systems was verified in both simulation and experimentally by the comparisons of the average Bit Error Rate (BER) and Error Vector Magnitude (EVM).     

具有电色散补偿的10 Gb/s脉冲转换器的研制

设计并研制了带电色散补偿功能的10 Gb/s脉冲转换器。电色散补偿通过时域均衡的方法,消除光纤色散带来的码间串扰;将电色散补偿芯片纳入脉冲转换器设计中,从而提高了其传输距离。所研制的样品光发射部分采用分布反馈激光器加电吸收调制器集成光源,接收部分采用带互阻放大器的雪崩光电二极管光电探测器模块,电色散补偿芯片对光电探测器输出的码流执行色散补偿算法。对样品进行的测试结果表明该脉冲转换器背对背接收灵敏度为-24.6 dBm,经过100 km G.652光纤传输后接收灵敏度为-20.8 dBm。未加电色散补偿功能时,采用相同的光源传输距离仅为50 km。     

Penalty Evaluation Due to the Cascade and Frequency Misalignment of AWG-Based Optical Add-Drop Multiplexers in 10 Gb/s Metro Core Ring Networks

The performance evaluation of AWG-based OADMs due to filter cascade in 10 Gb/s WDM metro core networks is presented. The penalty for the through optical channels is investigated versus the laser wavelength drift and OADM temperature stabilization failure. Results are measured and extrapolated with simulation results to obtain the maximum allowable number of OADMs in the metro network.     

Penalty Evaluation Due to the Cascade and Frequency Misalignment of AWG-Based Optical Add-Drop Multiplexers in 10 Gb/s Metro Core Ring Networks

The performance evaluation of AWG-based OADMs due to filter cascade in 10 Gb/s WDM metro core networks is presented. The penalty for the through optical channels is investigated versus the laser wavelength drift and OADM temperature stabilization failure. Results are measured and extrapolated with simulation results to obtain the maximum allowable number of OADMs in the metro network.     

10 Gb/s光纤通信系统一阶偏振模色散动态补偿系统反馈控制的实现

在偏振模色散(PMD)自动补偿技术中,如何根据反馈信号得到相应的控制信号,使补偿速度跟随偏振模色散变化始终是该技术的一个核心问题。提出了一种新颖的自适应抖动跟踪算法,完成了以微波信号为反馈的多自由度的一阶偏振模色散自动反馈补偿系统的跟踪补偿实验。算法成功地解决了传统算法在跟踪搜索过程中易陷入局部极值的问题,有效地克服了系统中的重要控制器件偏振控制器的磁滞现象以及动态补偿时跟踪搜索过程中易出现的瞬间恶化现象。实验结果表明该算法在对出现突发偏振模色散扰动后自动进行补偿的响应速度在ms量级,最快能达到1~2 ms。     

Experimental Study of Single- and Multicast Wavelength Conversion at 10 Gb/s Exploiting Four-Wave Mixing in Highly Non-Linear-Photonic Crystal Fiber with Widely Tunable Conversion Range

Abstract

Optical networking applications require the use of all-optical wavelength converters with input and output wavelength tenability as well as large numbers of multicasting channels. This article demonstrates the single-to-multiple wavelength conversion via multiple four-wave mixings between a 10-Gbit/s return-to-zero signal and several continuous waves co-propagating in a dispersion-flattened highly non-linear photonic crystal fiber. For single-to-single channel wavelength conversion, a wide conversion range of 31 nm is achieved with the optimal conversion efficiency of ?21.4 dB. By employing several continuous-wave probe lights, tunable single-to-dual and single-to-triple channel wavelength conversions are experimentally demonstrated, respectively. Moreover, the dynamic characteristics of the designed wavelength converter are studied under the conditions of variable input powers, polarization mismatch, and different lengths of the highly non-linear-photonic crystal fiber. The system is transparent to both bit rate and modulation format. This is very useful for engineering design and applications of optical-fiber-based wavelength converters in future ultra-high-speed photonic networks.     

40Gb/s光纤传输单边带归零信号的产生和性能分析

对光的单边带归零信号（SSBRZ）的一种产生方式进行了推导.通过合理设置调制器的偏置电压，使产生的SSBRZ信号的一个边带得到更有效的抑制，而且没有引起光脉冲的变形.对其在普通单模光纤（SMF）40Gb/s传输系统中的传输进行了仿真，并和归零（RZ）信号、载波抑制的RZ（CSRZ）信号的性能相比较，结果表明：在色散完全补偿的单信道传输系统中，SSBRZ的抗非线性能力比RZ、CSRZ强.     

Performance analysis of NRZ, RZ, CRZ and CSRZ data formats in 10 Gb/s optical soliton transmission link under the impact of chirp and TOD

This paper presents the performance analysis of non-return-to-zero (NRZ), return-to-zero (RZ), chirped return-to-zero (CRZ) and carrier suppressed return-to-zero (CSRZ) data formats in optical soliton transmission link under the impact of chirp and third-order dispersion (TOD). The performance of these data formats has been analyzed on the basis of certain performance metrics, viz, bit error rate (BER), Q² (dB), OSNR, eye opening, etc. It has been reported here that the performance of CRZ and CSRZ modulation format is better as compared to NRZ and RZ in a soliton transmission link. Further, CSRZ modulation format has been found to deliver optimum performance on the basis of performance evaluation metrics reported in this paper. In case of NRZ and CSRZ, comparatively narrow power spectrum has been observed. Best eye opening, highest value of Q² (dB) of 18 dB and lowest value of BER of the order of 10⁻¹⁶ has been reported in case of CSRZ among the considered data formats. The results have been obtained by varying noise figure from 3.0 to 9.0. No considerable effect of noise was observed. It was observed that at very narrow and ultra short pulse width, OSNR value suffers heavily and reduced to even negative values in dB, thus inducing a high degree of OSNR power penalty. The results were obtained by varying chirp factor from −0.6 to +0.6. Negative chirp resulted in improved OSNR as compared to positive chirp. RZ data format yielded a broader optical spectrum, comparatively low spectral efficiency and poor OSNR thus it was found that RZ format is not suitable for optical soliton transmission under the impact of chirp and TOD.     

Comparative investigation and suitability of various data formats for 10 Gb/s optical soliton transmission links at different chirps

This paper presents the comparative investigation and suitability of various data formats for optical soliton transmission links at 10 Gb/s for different chirps (−0.7 to 0.7). Here the investigations focused on data formats: NRZ, RZ soliton, RZ raised cosine and RZ super Gaussian. The comparative results and suitability of data formats is based on various performance measures such as Q-factor, eye opening, BER and jitter. It has been indicated that RZ super Gaussian yields the highest value of Q (34.08 dB), good eye opening and lowest BER.     

Impact of optical modulation formats on SPM-limited fiber transmission in 10 and 40 Gb/s optimum dispersion-managed lightwave systems

In this paper, 10 and 40 Gb/s optical systems have been investigated for nonreturn-to-zero (NRZ), return-to-zero (RZ), carrier-suppressed return-to-zero (CSRZ) and RZ-differential phase-shift-keying (RZ-DPSK) data formats. For the range of the optical signal power from −5 to 15 dBm, a maximum self-phase modulation (SPM)-limited transmission distance L_SPM is determined with eye-opening penalty (EOP) >1 dB .The observations are based on the modeling and numerical simulation of optimum dispersion-managed transmission link. Transmission over distances of the order of several hundreds of kilometers has been shown with and without amplified spontaneous emission (ASE) noise of the in-line erbium-doped fiber amplifiers (EDFAs).     

Significance of prechirping on long-haul path-averaged soliton impulse in re-circulating loop at 10 and 20 Gb/s with TOD

In this paper, we have investigated the performance of first- and second-order path-averaged soliton long-haul transmission link including the impact of third-order dispersion (TOD) at varied chirp. Here, the varied chirp is considered keeping in view the inadvertent frequency chirp imposed on all practical sources of short optical pulses. The propagation of strongly chirped pulses in loss-managed long-haul path-averaged soliton transmission network has been shown. The investigations reveal that in first-order (N=1) path-averaged soliton transmission link at 10 and 20 Gb/s, SPM effect on the rising and falling edges of a pulse results in spectral broadening for all values of induced chirp. On the contrary, spectral narrowing of the pulses is observed in second-order negatively chirped path-averaged soliton pulses. The effect of the nonlinearity changes from narrowing to broadening of pulses if the sign of the initial chirp is changed to positive. The results ascertain that the system is capable of transmitting a pulse up to the distance of 24,500 km at bit rates of 10 and 20 Gb/s. Investigations have been carried out by varying the chirp factor in the range −1 to 1 and −1 to 0.4] for 10 and 20 Gb/s, respectively, to demonstrate the robustness of the long-haul soliton link. The observations establish that the pulse width (full-width at half-maximum (FWHM)) remains within the optimal range even at the transmission distance of 24,500 km without and at discrete values of the chirp factor.