High-Efficiency Laser-Power Transmission With All Optical Amplification for High-Transmission-Capacity Submarine Cables

We present new trends in the performance evaluation of submarine fiber cable system with different ultrahigh multiplexing and propagation techniques over a wide range of the affecting parameters. Our model takes into account the ultimate optical transmission of huge submarine cables with 14,400 channels under different depth conditions. We employ Raman and erbium-doped fiber amplifiers in our study. We investigate the double impact of both temperature and pressure through the defined depth penalty. We also study the soliton transmission technique using two multiplexing methods considered in the design of ultra-wide wavelength division multiplexing (UW-WDM) with 14,400 optical channels and ultra-wide space division multiplexing (UW-SDM) with 440 fiber links. Based on experimental data, both the deep ocean water temperature and pressure are obtained as functions of the water depth.     

基于高非线性光纤的增益谱平坦拉曼光纤放大器研究

针对光纤通信中密集波分复用系统各信道的在线平坦光放大这一光通信问题,提出利用级联高非线性光纤来设计增益平坦的拉曼光纤放大器。对高非线性光纤(As S光纤)拉曼增益谱前后沿进行线性拟合处理,利用不同波长泵浦抽运同种光纤,实现前放大后增益补偿,并考虑信号光损耗不同,在输出端得到了一个近似固定的功率输出值,并分析了影响拉曼光纤放大器输出特性的因素。模拟结果表明:平均增益为20.45 dB,增益平坦度为0.15 dB。     

Proposed Power-Equalized EDFA Modules Using Fiber Bragg Gratings with Various Reflectivities

We proposed and experimentally demonstrated two power-equalized erbium-doped fiber amplifier (EDFA) modules using fiber Bragg gratings (FBGs) with various reflectivities for individual channels. The transmission type power-equalized EDFA module is low-cost for its simple design, while the reflection type power-equalized EDFA module can suppress most of the amplified spontaneous emission noise. Both consist of a bidirectional EDFA, a set of FBG chains with suitable reflectivities, and an optical isolator/optical circulator. They can find potential applications in wavelength division multiplexing lightwave transmission systems.     

Study on a Multiplexer a 40 Gb/s OTDM System

In a 4?0Gb/s OTDM system (optical time-division-multiplication) system, multiplexing devices are key devices. The time interval of four channels of the 40Gb/s OTDM system is 25ps respectively. If the time intervals are no accurate, will induce the system performance to degeneration. In order to make out OTDM device and carry out a transmission experiment in a 40Gb/s OTDM system, a kind of OTDM device is researched. This scheme be used to fabricate multiplex device. Also the device have been used to a 40Gb/s OTDM system. Our experimental results shows that, the multiplex device based on the six 1 optical fiber couplers can be used to multiple at a time domain.That make four 10Gb/s optical signals multiple to 40Gb/s. The time interval error of each of channels is not bigger than 1ps, inserted loss is smaller than 2dB.     

Spectral efficient hybrid wireless optical broadband access network (WOBAN) based on transmission of wireless MIMO OFDM signals over WDM PON

In this paper, a spectral efficient hybrid wireless optical broadband access network (WOBAN) is proposed and demonstrated based on the transmission of wireless multi-input multi-output orthogonal frequency division multiplexing (MIMO OFDM) signals over wavelength division multiplexing passive optical network (WDM PON). By using radio over fiber (ROF) techniques, the optical fiber is well adapted to propagate multiple wireless services having different carrier frequencies. It is a known fact that multiple wireless signals having the same carrier frequency cannot propagate over a single optical fiber at the same time, such as MIMO signals feeding multiple antennas in fiber wireless (FiWi) system. A novel optical single-sideband frequency translation technique is designed and simulated to solve this problem. This technique allows four pairs of wireless MIMO OFDM signals with the same carrier frequency for each pair to be transmitted over a single optical fiber by using one optical source per wavelength. The crosstalk between the different MIMO channels with the same frequency is eliminated, since each channel is upconverted on specified wavelength with enough channel spacing between them. Also the maximum crosstalk level between the different MIMO channels with different frequencies is very low around ?76 dB. The physical layer performance of the proposed WOBAN is analyzed in terms of the bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). The proposed WOBAN achieves 7.68 Gb/s data rate for 20 km for the optical back-end and 240 Mb/s for the outdoor wireless front-end.     

Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.     

Crosstalk in a bidirectional optical fiber

Full-duplex communications in a single optical fiber is both feasible and practical in certain applications. The main problem is crosstalk between the two directions. This paper reviews the sources of crosstalk, gives its magnitude, and describes techniques to reduce crosstalk. An example is a system that requires 75 optical dB of isolation between transmitted and received signals at each terminal. There are two sources of optical crosstalk. The first occurs in components such as couplers and connectors and can be held below 50 dB by careful design. The second is Rayleigh scattering within the fiber, which increases system noise as well as crosstalk between counterdirectional signals.     

Maximization of repeater spacing in ultrawide-wavelength-division multiplexing optical communication systems based on multipumped laser diodes

We show that the amplifier bandwidth can be further increased and the gain spectrum can be tailored if one uses pumping with multiple laser wavelengths. We consider the wide-gain amplifier where four sets of multipumps are employed. We process two multiplexing techniques in long haul transmission cables where the number of channels is up to 9600 in ultrawide-wavelength-division multiplexing (UWWDM) with employment of the ultrawide-space-division multiplexing (UW-SDM) technique to merge the number of links up to 400 in the optical-fiber core over wide ranges of affecting sets of parameters. As well as the repeater spacing using a multi-pumping Raman amplifier, we investigate N _R pumps in the optical pumping wavelength (from 1.36 to 1.44 μm) to amplify optical channels where the optical wavelength range (1.45–1.65 μm) satisfies near infrared optical transmission region.     

S波段宽带光纤喇曼放大器研究

在PTDS(Photonic Transmission Design Suite)仿真平台上,用3个泵浦源的RFA实现了S波段的增益平坦,同时对泵浦光与信号光,信号光与信号光,泵浦光与泵浦光之间的相互作用以及RFA的噪声特性进行了研究.     

Control packet signaling mechanism using electronic code division multiple access for packet-based networks

We propose and experimentally demonstrate the feasibility of a control packet signaling technique using electronic code division multiple access for a wavelength division multiplexing packet-based network, whereby each wavelength channel is assigned a unique electronic code based label on a radio frequency subcarrier. Such a technique allows each wavelength channel to be electronically identified without requiring the use of a WDM demultiplexer. We experimentally demonstrate this technique with two wavelength channels each with 1.25 Gb/s baseband payload data and 10 Mb/s header coded onto an electronic code at 160 Mb/s. A performance study of the electronic code division multiple access based control signaling scheme in a wavelength division multiplexed packet-based access network is also performed in terms of the required power budget to monitor the electronic code division multiple access control signals in the presence of several sources of noise for error-free transmission of both payload data and electronic code division multiple access based control signals. It is shown that the modulation depth of each signal impacts the amount of required optical tap power. As the modulation depth of the electronic code division multiple access based control signal is increased, the required optical tap power is reduced. However, this increases the bit-error-rate for the payload data. Therefore, there lies a maximum and a minimum of the required tap optical power for the successful recovery of both signals. The lower bound of this range is usually determined by the successful recovery of electronic code division multiple access based control signal while the upper bound is determined by the successful recovery of payload data. The required optical tap power is analyzed for different transmission bit rates of the payload data for various receiver architecture scenarios without an optical amplifier at the receiver. The scalability analyses were repeated with an optical amplifier placed in the receiver terminal of the network. The resulting optical tap power that is required for the successful monitoring of the electronic code division multiple access based control signals are compared with that of the case without the amplifier.     

Research on WDM optical fiber transmission system based on fiber Raman amplifier

After wavelength division multiplexing (WDM) optical fiber transmission system based on fiber Raman amplifier (FRA) is investigated in detail, the influence of the collocation of dispersion compensation fiber (DCF), the dispersion coefficient, dispersion slope (DS), effective core area, nonlinear index, length of FRA, launch power and the bandwidth of Bessel filter on bit error rate (BER) is deduced. The influence of Rayleigh backscattering noise on optical signal noise ratio (OSNR) is also investigated, which affects the performance of long haul transmission badly. The result indicates that the broadband long haul transmission can be realized through the reasonable design of the fiber. The result is useful to the optimal design of the WDM optical fiber transmission system based on FRA.     

Tbit/s超大容量光纤通信系统的研究进展

Tbit/s超大容量光纤传输系统促进了光纤通信技术的发展。综述了采用波分复用技术(WDM)、光时分复用技术(OTDM)和WDM/OTDM混合方式的Tbit/s超大容量光传输系统的研究现状、技术实现方式及研究的最新进展。对各种传输系统的优缺点进行了评价,对Tbit/s光纤通信系统的前景作了展望。     

Crosstalk in a bidirectional optical fiber

Abstract

Full-duplex communications in a single optical fiber is both feasible and practical in certain applications. The main problem is crosstalk between the two directions. This paper reviews the sources of crosstalk, gives its magnitude, and describes techniques to reduce crosstalk. An example is a system that requires 75 optical dB of isolation between transmitted and received signals at each terminal. There are two sources of optical crosstalk. The first occurs in components such as couplers and connectors and can be held below 50 dB by careful design. The second is Rayleigh scattering within the fiber, which increases system noise as well as crosstalk between counterdirectional signals.     

Technical study of visible light wavelength division multiplexing using polymer optical fiber

Visible light wavelength division multiplexing (VWDM) experiment was performed using polymer optical fiber (POF). Lights of two different wavelengths (650 and 530 nm) were sent to a single POF. Red light (650 nm) was used for 100-Mb/s full duplex IP data transmission and green light (530 nm) was used for voice signal transmission. Light sources are light-emitting diodes (LEDs). A POF coupler (splitter) and the prisms were employed as multiplexer and demultiplexer, respectively. The channel isolation and insert loss were measured, which are 20.5 and 17.65 dB for 650-nm channel respectively, and 19.16 and 20.55 dB for 530 nm one respectively.     

Analysis of Methods of Performance Evaluation of Direct-Detection Orthogonal Frequency Division Multiplexing Communication Systems

Abstract

The performance assessment of orthogonal frequency division multiplexing signals in direct-detection transmission systems by using the error vector magnitude and several bit error ratio approaches is analyzed and compared through numerical simulation. It is shown that excellent accuracy of the bit error ratio estimates is obtained by a semi-analytical Gaussian approach for all the orthogonal frequency division multiplexing system configurations analyzed and that the error vector magnitude only provides reliable estimates of the system performance when the system is dominantly impaired by noise. Additionally, a novel Q-factor approach for orthogonal frequency division multiplexing optical signals showing improved bit error ratio estimates is also presented.     

掺铒光纤放大器在多路模拟光纤传输系统中应用

对应用掺铒光纤放大器的副载波频分复用模拟电视光纤传输系统的噪声和失真进行了实验研究，利用掺铒光纤放大器作为系统的功率提升和中继放大器，分别成功地进行了１８５ｋｍ和２１５ｋｍ的系统传输试验     

基于磁光效应的二维三角晶格光子晶体模分复用器

随着全光通信的快速发展, 波分复用传输系统已不能满足高容量光网络的需求, 而模分复用技术利用有限的稳定模式作为独立信道传递信息, 可以成倍地提高系统容量和频谱效率, 是构建未来光网络的关键技术之一. 本文基于掺Bi复合稀土铁石榴石的磁光效应, 设计了1.55 μm波段的二维三角晶格光子晶体模分复用器. 在该光子晶体结构中引入缺陷, 形成模式分束波导, 通过外加磁场改变其在不同偏振模式下的磁导率, 从而控制TE, TM模式的传输, 实现了1.55 μm波段的模分复用. 利用平面波展开法和时域有限差分法对此模分复用器进行了能带和传输特性分析, 结果表明: TE和TM模式的透射率均高于92%, 信道隔离度分别为19.7 dB和42.1 dB. 这些特性在未来的大容量光传输系统中有着重要的应用前景.     

Collective reception of orthogonal band multiplexed data streams for OFDM-PON upstream transmissions

We propose and demonstrate a novel OFDM-PON upstream transmission architecture with traffic aggregation by orthogonal band multiplexing. The aggregated data streams that propagate in different fiber lengths from ONUs are collectively received and demodulated using one receiver, when the OFDM signals are in a synchronous state. In simulation, four optical network units (ONUs) transmit upstream data at four different frequency bands, and use orthogonal band multiplexing with a proper configuration. The orthogonal band multiplexed 10-Gb/s OFDM signal is collectively received to validate the feasibility of the architecture. We also conduct a proof-of-concept experiment to verify the orthogonal band multiplexing and collective reception. We also verify that the tolerance to the time mismatch of the orthogonal band multiplexing is twice of the CP length.