基于混合光纤放大器的波分复用光纤传输系统研究

在研究了入纤功率、光器件的插入损耗以及非归零码中1码出现的概率对系统误码率影响的基础上,提出了一种基于混合光纤放大器的波分复用(WDM)光纤传输系统设计方案,并对该系统的噪声特性进行了详细地研究。提出了一种抑制前向噪声的有效方法,实现了20路WDM信号320km无误码传输。试验结果对基于混合光纤放大器的波分复用光纤传输系统的设计具有一定的指导意义。     

马丁内兹型啁啾脉冲放大系统高阶色散的混合补偿

采用光线追迹法对含有马丁内兹型展宽器的CPA系统的各阶色散进行了系统的理论研究，提出了引入适当负三阶色散量以补偿五阶色散的总体色散的混合补偿方法.该方法能够获得比采用仅补偿二、三阶色散的逐阶色散补偿法更接近傅里叶变换极限的超短脉冲. 关键词： 啁啾脉冲放大 马丁内兹型展宽器 色散补偿     

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

In this work, different novel 3×1 multiplexer structures for being used in polymer optical fiber networks are proposed. Designs are compact, scalable, and of low consumption, capable of operating in a large wavelength range simultaneously 660, 850, and 1300 nm, due to the use of nematic liquid crystal cells. Light that comes from each input port is handled independently and eight operation modes are possible. Control electronics has been made using a programmable integrated circuit. Electronic system makes available the managing of the optical stage using a computer. An additional four optical sensors have been included for allowing the optical status checking. Finally, a polarization independent multiplexer has been implemented and tested. Insertion losses less than 4 dB and isolation better than 23 dB have been measured. In addition, 30-ms and 15-ms setup and rise times have been obtained. The proposed multiplexer can be used in any polymer optical fiber network, even in perfluorinated graded index one, and it can be specially useful in optical sensor networks, or in coarse wavelength division multiplexing networks.     

Er-doped concentric-cores optical fiber for simultaneous amplification and compensation of positive dispersion

The Er-doped concentric-cores dispersion compensating fiber (EDDCF) has been demonstrated. The rare earth has been doped as a ring around the inner core. We have obtained 14-dB gain at 1550 nm (using the optical fiber network where amplification as well as negative dispersion are necessary.     

All-optical wavelength converters for optical switching applications

We present the latest results about all-optical wavelength conversion obtained within the European Union—funded RACE ATMOS project. In particular, solutions based on carrier depletion in Distributed Brag Reflector lasers have reached penalty-free polarization-insensitive operation at up to 2.5 Gbit/s, while solutions based on Semiconductor Optical Amplifiers (SOAS) under cross-gain modulation have been demonstrated at more than 20 Gbit/s. The study of cross-phase modulation in SOAs has also been performed, leading to the monolithic integration of SOAs within an interferometer, according to structures proposed by the project. Penalty-free operation at up to 10 Gbit/s as well as signal reshaping have been obtained with such devices. Besides the study of components, wavelength converters have been used in several demonstrators assessing their maturity and compatibility with photonic-switching applications.     

Polarization mode dispersion and chromatic dispersion compensation by using a three-stage compensator

A three-stage compensator used for Polarization mode dispersion (PMD) and Chromatic dispersion (CD) compensation is proposed. The compensator is capable of compensating the two components of second-order PMD when no CD exists. Two operating points of compensating second-order PMD have been proposed. Two-stage and three-stage compensators are compared by the outage probability. When CD is introduced, the compensator should retain a quantity of second-order PMD to compensate CD. The outage probability when PMD and CD coexist has been calculated. The results show that a tradeoff must be made in order to compensate CD and PMD at the same time.     

Analysis of all optical cascaded XGM wavelength converter using CW-holding beam

In this paper, we propose and analyze a wavelength conversion using an cross-gain modulation (XGM) with two semiconductor optical amplifiers and CW-holding beam for improvement of wavelength conversion speed and frequency chirp characteristics. Wavelength conversion characteristics of the cascaded XGM with a CW-holding beam are investigated in time domain. From the simulation, we have observed that the proposed scheme provides a non-inverted efficient wavelength conversion and frequency chirp reduction at higher bit rate operation.     

Simultaneous dispersion and non-linearity compensation with mid-span optical phase conjugation and distributed Raman amplifier for a sub-carrier multiplexed optical transmission link

Optical phase conjugation (OPC) and distributed Raman amplifier (DRA) combination (OPC-DRA) is demonstrated as a potential enabling solution for simultaneous reduction of fiber non-linearities and dispersion compensation of a sub-carrier multiplexed (SCM) optical transmission link. The present work is focused on the use of OPC-DRA combination for system performance improvement in terms of composite second order distortion (CSO) and carrier to noise ratio (CNR) of the SCM link. The analysis further shows that, introduction of DRA with proper pumping scheme significantly reduce fiber non-linearity resulting in improvement of the system performance in terms of CNR, compared to the situation where only mid-way optical phase conjugation is used.     

Multimode optical fiber demultiplexer-star coupler using a single gradient-index-rod lens and a multi-facet grating

An optical fiber multi-function device consisting of a single gradient-index-rod lens and a multi-facet blazed reflection grating is proposed to simultaneously realize functions of wavelength demultiplexing and optical signal distribution in a multimode optical fiber transmission system. We analyzed the demultiplexing characteristics and the tolerance of optical components using the ray trace method. This device can realize not only low loss optical signal distribution but also offers improved demultiplexing characteristics in comparison with the previously proposed demultiplexer-multiposition switch. The following characteristics are expected from the design using commercially available optical components: a working band of 0.64–0.88 μm, channel separation of 34–36 nm, 3 dB bandwidth of 27–28 nm, channel cross-talk of less than - 40 dB and minimum excess insertion loss of 0.9–2.1 dB.     

Investigations on order and width of RZ super Gaussian pulse in different WDM systems at 40 Gb/s using dispersion compensating fibers

In optical wavelength division multiplexed (WDM) systems the dispersion management is a key issue. In optical systems a lot of research is going on to reduce dispersion by selecting proper dispersion compensating techniques and proper modulation format for input data. One way to reduce dispersion is by using dispersion compensating fibers in the WDM systems. This paper analyzes the use of RZ super Gaussian pulse inputs for different WDM systems i.e. for conventional, dense and ultra dense WDM systems employing dispersion compensating fibers. The pulse width and the order of the RZ super Gaussian pulse was varied to evaluate the performance at 40 Gb/s. The experiment showed that to get minimum BER, pulse width of 7.5 ps and 10 ps along with third-order RZ super Gaussian pulse were found suitable and recommended to be used.     

混沌光通信与OC-48光纤通信的波分复用

数值证实并分析了混沌激光通信与现行光通信的波分复用传输,对于100 GHz的信道间隔,混沌激光通信系统实现了传输速率为1 Gbit/s数字信号的保密传输,现行光通信系统实现了传输速率为2.5 Gbit/s数字信号的传输.研究表明,当现行光通信中脉冲光信号的峰值功率不超过17 dBm时,混沌激光通信可在传输距离80 km内实现并行传输.此外,当现行光通信中脉冲光信号的峰值功率为7 dBm时,系统接收到的信号质量受混沌激光通信的干扰很小,当光纤传输距离从80 km增加到160 km时,对应的眼图开启度从82% 关键词： 混沌光通信 混沌同步 波分复用 信道串扰     

集成双波导半导体光放大器光开关实现波长转换的理论研究

建立了基于集成双波导半导体光放大器的光开关(ITG-SOA-Switch)的理论分析模型.与半导体光放大器(SOA)的特性相比较表明，由于ITG-SOA-Switch合并了多种物理效应，故其静态增益饱和曲线在饱和功率点附近具有大幅度陡峭下降的独特性质.理论分析和10 Gbit/s波长转换模拟结果显示，恰当地选择输入抽运光的功率范围，ITG-SOA-Switch波长转换器输出转换光的消光比特性较之输入抽运光会有显著的改善. 关键词： 波长转换 半导体光放大器 集成双波导半导体光放大器 光开关     

Maintaining single polarization and dispersion compensation with modified rectangular microstructure optical fiber

In this paper, we propose and numerically demonstrate a highly birefringent microstructure optical fiber which shows negative dispersion coefficient of about −288 to −550 ps/(nm km) covering S to L wavelength bands and −425 ps/(nm km) at the excitation wavelength 1550 nm. This proposed design successfully compensate the dispersion covering S to L communication bands ranging from 1460 to 1625 nm along with relative dispersion slope (RDS) perfectly matched to that of single mode fiber of about 0.0036 nm⁻¹. Apart from dispersion compensation, the designed MOF offers high birefringence of 2.94 × 10⁻² at 1550 nm and better compensation ratio with design simplicity due to circular air-holes in the fiber cladding.     

A novel approach to all-optical wavelength conversion by utilizing a reflective semiconductor optical amplifier in a co-propagation scheme

Nonlinear optical gain modulation in an InGaAsP/InP bulk reflective semiconductor optical amplifier (RSOA) is studied. The differences of the optical properties between RSOAs and conventional SOAs are initially investigated. All-optical wavelength conversion based on nonlinear gain modulation in RSOAs is demonstrated at a bit rate of 2.488 Gbit/s. It is shown that a bit-error-rate of <10⁻⁹ can be achieved and an extinction ratio of >9 dB can be obtained at a bit rate of 2.488 Gbit/s with a 2³¹-1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). In comparison with conventional SOAs, wavelength conversion by RSOAs shows much improved performances in high-speed all-optical wavelength conversions.     

Amplification of 12 × 10 Gb/s WDM signals with negligible FWM crosstalk in a double-pumped fiber optical parametric amplifier

We report on the amplification of 12 × 10 Gb/s wavelength-division-multiplexed signals by a double-pumped fiber optic parametric amplifier (2P-FOPA). A gain of 10 dB is obtained using a 4.3 km-long conventional dispersion shifted fiber (DSF) as nonlinear medium. Our spectra show negligible generation of spurious FWM products, and we attribute this to the small variations of the zero-dispersion wavelength of the DSF. The 2P-FOPA performance is assessed through Q-factor measurements, and we show that for output powers per channel ranging from −15 to 3 dBm the power penalty is less than 0.5 dB.     

宽带色散补偿光子晶体光纤的设计与优化

提出了一种新型的宽带色散补偿光子晶体光纤。通过增大光子晶体光纤(PCF)包层第一环空气孔半径r1,同时优化孔间距和包层其它环空气孔,在1550nm波长处获得了低至-1906.4ps/nm/km的负色散值。针对常规单模光纤的色散特性,设计出了宽带色散补偿光子晶体光纤,可补偿23倍长度的常规光纤,补偿的带宽达330nm,这在WDM系统中对多个信道同时进行色散补偿具有非常重要的意义。     

Performance of an optical wideband WDM system considering stimulated Raman scattering,fiber attenuation and chromatic dispersion

The performance of an optical wideband wavelength division multiplexed (WDM) communication system is analyzed considering the effects of stimulated Raman scattering, fiber attenuation and chromatic dispersion. Improved models for the Raman gain and the fiber attenuation constant are proposed, which yield better and reliable performance results of the WDM system. Effect of fiber chromatic dispersion is also investigated and it is observed that dispersion can suitably be selected to overcome the limitations imposed by the stimulated Raman scattering phenomenon.     

200 km沙漠链路高精度光纤时频传递关键技术研究

针对沙漠环境实地链路存在的温度变化大、室外风力、地表振动等多种复杂噪声来源,通过对系统反馈补偿带宽、反馈补偿强度、光功率等时频传递系统关键参数的优化配置,研究了不同反馈补偿参数下复杂链路噪声的有效抑制技术.全链路的频率传递稳定度8×10~(-14)@1s,1×10~(-16)@1000 s,千秒尺度下时间信号传递的时间方差仅为1.2 ps.实现了氢钟信号在200 km量级沙漠环境实地链路的无损传输.该验证实验在基于短基线干涉测量的卫星测轨系统中发挥了重要作用.     

A novel actively and passively mode-locked semiconductor optical amplifier fiber ring laser

A novel actively and passively mode-locked semiconductor optical amplifier fiber ring laser was presented, where semiconductor optical amplifier provided cavity gain and introduced nonlinear polarization rotation, whereas, intensity modulator not only acted as modulator but also polarizer. The pulses with duration below 3 ps (FWHM) and peak power about 16 mW at a repetition rate of 10 GHz can be obtained in our system and the system stability may be enhanced. To investigate system parameters effects on mode-locked pulses, a theoretical model was developed.