A novel mapping multiplexing technique for high speed optical fiber communication systems

Optical signal to noise ratio (OSNR) is a critical performance parameter of an optical fiber communication system. A method for OSNR monitoring based on coherent optical sampling technology is presented. The estimated error of a 10-GBd QPSK signal is <1 dB with the actual OSNR in range of 12 to 30 dB. The influence of uneven spectrum of a local oscillator on the measured accuracy is investigated, and a compensated algorithm for such unevenness is provided. Our method has the advantage of lower complexity and can be extended to higher symbol rate communication system requiring no high bandwidth ADC hardware.

A novel method to compensate dispersion and dispersion slope at the same time by using fiber Bragg grating written on the tapered core fiber has been presented. The fabrication method about this kind of tapered core fiber has been realized by precisely controlling the fiber's diameter during the process which is drawing the preform into optical fiber. The fiber grating written on this kind of fiber has parameter as 3dB bandwidth 0.861nm. Its dispersion value is −1159ps/nm (within 0.8nm bandwidth), and the dispersion slope is −1.3 ps/nm2. These characteristics of the grating make it can be used in high speed optical fiber communication systems which need the dispersion and dispersion slope be compensated at the same time.

Wideband optical waveguide phase modulator is a basic device in high speed or coherent optical fiber communication system. Because of the limit from electrode capacitance, conventional modulators based upon standing wave voltage E / 0 modulation hardly get the bandwidth as wide as several GHz. This paper presents an optical waveguide phase modulator, which takes the advantage of travelling-wave modulator. Its 3dB bandwidth of phase modulation index (5 (peak to peak value) has reached 6 GHz, while the total insertion loss is moderately 5dB in all over the band.

One of the basic needs of people is to communicate with each other. Many advanced communication schemes and devices have been designed to fulfill the requirement of the users. The invention of such advanced applications have led to huge increases in bandwidth. To meet the demands of bandwidth due to multiple users at the same time, various modulation and multiplexing schemes have been developed. Moreover, the designed fiber system must achieve the desired data rate that must have robust transmission and be cost efficient. This study's goal is to construct a full-duplex communication system using SMF and FSO (FSO). In places where cost of implementation becomes more or optical fiber is not applicable for laying, then the systems with FSO link are employed. With the use of pilot-assisted Coherent optical orthogonal frequency division multiplexing (CO-OFDM), Optic 16-QAM is utilized to boost data rate and transmit range. To improve the Figure of Merit (Fom) of a full duplex system, optical 16-QAM, 32 QAM, 64 QAM or 256 QAM has been used. The performance has been studied under various weather conditions. Numerous characteristics such as the Error Vector Magnitude (EVM), the Bit Error Rate (BER), the eye diagram, the optical signal to noise ratio, and the spectrum efficiency are measured and compared to traditional approaches.

At present, optical fiber communication systems are developing in the direction of large capacity, high speed, long distance, etc., making nonlinear effects and polarization mode dispersion (PMD) and other optical fiber performance defects that were negligible for low-rate systems become the main factors limiting system upgrades and transmission distances. Polarization mode dispersion is an important factor affecting the performance of optical fiber communication systems, and it has become one of the main obstacles to the development of high-speed and long-distance optical fiber communication systems. It can cause pulse widening in the digital transmission system, thereby limiting the transmission rate of the system. Therefore, the influence of polarization mode dispersion on the transmission system and the compensation method are analyzed in this paper.

光纤通信已经成为目前通信网络发展的主流方向。但是随着光纤通信系统向着超远距离、超大容量、超高速率的方向发展，光纤色散已经成为其巨大的阻碍。如何有效地控制光通信系统中产生的色散，使光信号在大容量、高速率、长距离传输中无误码地到达接收端，已经成为人们迫切需要解决的问题。对光通信系统中的色散进行监测并进行动态补偿的研究，使得超大容量、超长距离、超高速率的光纤通信系统成为可能，有助于最终实现全光智能自动交换网络。在众多测量光纤色散的方法中，调制相移法具有结构简单，可靠性强等优点。本文中，我们对使用调制相移法测量光纤色散进行了研究和仿真，讨论了在不同光纤长度和不同调制频率下，影响调制相移法测量结果精度的因素。通过适当地选取调制频率，我们可以使用调制相移法测得不同光纤长度下色散的精确值。另外在本文中，我们通过仿真验证了调制相移法可以测量具有任意色散–波长曲线的光纤。因此在实际应用中，调制相移法是可以应用于高精度光纤色散的测量。 Optical fiber communication is the mainstream of communication development at present. However, with the development of optical fiber communication system which trending towards ultra-long length, ultra-large capacity and ultra-high speed, fiber dispersion turned to be a great obstacle. How to control the dispersion created in the optical communication system effectively while force optical signal to reach the receiving end in high-capacity, high-rate and error-free long-distance transmission has increasingly become a research focus of optical fiber communication systems. It is a great significance to research about monitor and dynamic compensate dispersion in the optical communication systems, so that the ultra-large capacity, ultra-long length and ultra-high speed optical fiber communication systems would not be impossible, all-optical intelligent network with automatic switching functions would come true. Among the varieties of methods to measure fiber dispersion, the phase-modulation shift method is the unique one, which has the advantages of simple structure, high reliability. In this paper, we make a research and simulate to use the phase-modulation shift method, meanwhile we also discuss about the factors which affect the accuracy of the results in the different fiber lengths and modulation frequencies. By the means that selecting appropriate modulation frequency, we can use modulation phase shift method to measure the exact value of dispersion comes out from different lengths of fiber. Moreover, this paper also proves that the phase-modulation shift method is able to measure the optical fiber with arbitrary dispersion-wavelength curve, which is already verified by our simulation. Therefore, the phase-modulation shift method is well to be applied to take practice in the high-precision fiber dispersion measurement.

Nowadays, the coherent optical communication system plays an important role in communication field because of large capability and bandwidth. A coherent optical communication, based on high-order modulation and digital signal processing technologies, consists of optical transmitters, optical fiber lines, optical amplifiers and optical receivers. In the high-speed coherent optical communication system, the phase noise from the transmitter laser and the local oscillator laser can significantly degrade the performance of the signal transmission and detection, especially for the systems using high-order modulation format, such as m-ary phase shift keying (mPSK) and m-ary quadrature amplitude modulation (m-QAM). Therefore, investigations on laser phase noise compensation algorithm based on digital signal processing technologies has become more and more significant. In this work, a multi-ring carrier phase recovery algorithm is developed for compensating the laser phase noise in optical fiber communication systems using high-order modulation formats. Degradations on the performance of communication systems due to the laser phase noise have been investigated. The system performance using the proposed algorithm and the conventional Viterbi-Viterbi algorithm were also evaluated in 9-channel and 15- channel, 32-Gbaud, Nyquist-spaced QPSK, 16-QAM, 64-QAM and 256-QAM coherent transmission systems with considering the impact of the laser phase noise. It is found that the phase noise leads to stricter constraints on the linewidths of transmitter-side and receiver-side lasers, and it can greatly degrade the achievable information rates in communication systems. Besides, compared to the conventional Viterbi-Viterbi algorithm, which is usually applied in the QPSK system, our proposed algorithm can also well mitigate the laser phase noise in 16-QAM, 64-QAM and 256-QAM optical communication systems.&#13;\n

As human society to the information in the process of moving and growing demand for bandwidth communications capacity, the optical of new modulation formats increasingly attention and quickly play an important role in optical communications. How can the system bit error rate within a certain degree of stability while still maintaining high-speed long-distance dispersal system, has been a popular issue is the optical communications industry. Starting from the optical modulation format herein, the generation process of the system introduced various optical signal modulation format, the optical signal through the optical fiber was studied and the performance of the simulation, on the basis of the design of advanced optical modulation formats in an optical fiber communication system .

In this paper, a germanium doped silica-based single-mode fiber for high speed optical communication link has been proposed. It is found that the proposed fiber is suitable for three transmission widows an excellent result at the third transmission window. Here, attenuation loss, dispersion, mode field diameter, bending loss, and material loss of the proposed fiber has been analyzed. It is found that dispersion such as material dispersion and waveguide dispersion is very low at the third transmission window (1550 nm), which is used for high speed optical fiber communication link. In addition to this, at the third transmission window, micro bending loss is almost disappeared and macro bending loss is also very low (0.00101 dB/km). All these analysis has been done using FDTD technique.

With the interconnection of regional grid and wide application of HVDC and FACTS in power grid, the scale of grid is increasing rapidly, and this makes the power system simulation techniques face new challenges. In this paper, based on decoupling algorithm and high speed optical fiber communication, the interconnection between multi-SGI(multiple SGI supercomputers) is proposed to implement HYPERSIM co-simulation. The HIL test of Yu’E MMC-HVDC project is implemented using the HYPERSIM co-simulation platform, the test results verify the real-time simulation capability of the proposed scheme.

For the shortcomings of traditional data communication electronic mode and bus interface, optical fiber communication electronic technology and compact peripheral component interconnect (CPCI) bus interface mode with industry standard are adopted to design a kind of optical fiber communication electronic data transmission mode. The optical fiber communication electronic board based on CPCI bus constitutes a novel optical fiber communication electronic system. In the process of hardware design, the small form-factor pluggable (SFP) transceiver module is used to convert the photoelectric signal and complete the transmission of optical fiber data. Regarding the existence of differential signal in high-speed serial circuit of electronic board, the wiring is reasonably arranged. The hardware test platform of optical fiber communication electronic system is built based on PCI9054 CPCI bus and industrial personal computer (IPC) communication electronics. FPGA with embedded high-speed serial transceiver module is adopted to design the hardware logic function. Binary gray code is used to count. FIFO protocol and Aurora protocol are supported. Protocol IP core is customized to realize the full duplex electronic communication of high-speed data. Considering the loss problem of the system, the grey model GM(1, 1), ARIMA model and Elman neural network are employed as the big data level research scheme, which are combined into the loss prediction model according to a certain proportion. In the experiment, the test of DMA data reading and writing function is designed, and the embedded highspeed transceiver module and optical fiber communication electronic logic function are simulated. The results show that the symbol error rate (SER) is always 0, and the low-pass filtering characteristics of the channel are effectively compensated, which makes the signal quality stabler. Compared with the single big data level research scheme, the combined model has smaller prediction error and higher prediction accuracy.

This Special Section of the IEEE Open Journal of Circuits and Systems is dedicated to a collection of articles on High-Speed Wireline and Optical Communication Circuits and Systems, to promote techniques in both circuit and system levels to tackle various challenges as the data rate keeps increasing and provide insightful guidelines for interconnects in the years to come. This Special Section covers articles in three categories including high-speed transceivers, multitone-modulations, and equalizations.

Polarization-mode dispersion (PMD) and polarization-dependent loss (PDL) are the main polarization effects that degrade intermetropolitan and transoceanic high-speed optical fiber communication systems [Huttner et al., 2000]. As a result of the stochastic nature of PMD [Khosravani et al., 2001], it is very difficult to compensate the performance degradation due to PMD, which leads to waveform distortions and signal depolarization. Because PMD causes random fluctuations of the polarization state of the light, the performance degradation due to PDL also becomes stochastic; leading to power fluctuation in wavelength-division multiplexed (WDM) systems, and producing additional waveform distortions.

The paper analyses the effects of intra-channel four-wave mixing (IFWM) on the high-speed optical fiber communication system. A new code format is developed with double 0 and double π phase separating 1 code; it can decrease the transmission penalty from fiber nonlinearity by counteracting the perturbation terms of IFWM. From the simulation of transmission of two classic code data “11011” and “11100”, we find that our proposed code format has a better suppression effect than the alternative modulation inversion (AMI) or the normal RZ format and supports a wider pulse mode. In a 40 Gbps system, the AMI format is 2 dB less than the RZ format, and our proposed format is 1 dB less than the AMI format when a 1 dB eye open penalty is taken as a metewand. Moreover, it can be realized as easily as the AMI format.

PMD mitigation through interleaving LDPC codes with polarization scramblers