In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are car...In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.展开更多
A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stabil...A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stability of the system as well as to reduce the interference with same nature are emphatically discussed. Finally, the experiment results of the developed instrument are given.展开更多
On the basis of analysis on the temperature monitoring methods for high voltage devices, a new type of fiber optic sensor structure with reference channel is given. And the operation principle of fiber optic sensor is...On the basis of analysis on the temperature monitoring methods for high voltage devices, a new type of fiber optic sensor structure with reference channel is given. And the operation principle of fiber optic sensor is analysed at large based on the absorption of semiconductor chip. The mathematical model of both devices and the whole system are also given. It is proved by the experiment that this mathematical model is reliable.展开更多
Information leaks through regular fiber optic communications is possible in the form of eavesdropping on conversations, using standard fiber optic communications as illegal measuring network. The threat of leakage of ...Information leaks through regular fiber optic communications is possible in the form of eavesdropping on conversations, using standard fiber optic communications as illegal measuring network. The threat of leakage of audio information can create any kind of irregular light emission, as well as regular light beams modulated at acoustic frequencies. For information protection can be used a means of sound insulation, filtration and noising. This paper discusses the technical possibilities of countering threats by monitoring the optical radiation to detect eavesdropping.展开更多
光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性...光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性,文章研究LDPC码的优化设计方法。先深入探讨LDPC码的基本原理及其在光纤通信中的应用,接着提出一种基于密度进化和有限字长效应分析的LDPC码优化方法,并通过光学特性仿真OptSim工具进行了验证。实验结果表明,优化后的LDPC码在不同码长下的误码率均取得了显著降低,特别是在长码字情况下,其纠错性能显著提升。展开更多
Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs)...Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs) and Raman amplifiers concatenated as booster amplifier. The channel imbalance of the overall system changes with different sets of power launched into EDFAs. By appropriately choosing the power input to concatenated EDFAs, the output spectrum of 40 channel signal can be equalized to the most extent. The merit of benefit can be around 5.5 dB by this pre-emphasis equalization. The requirement for the gain equalizer is therefore greatly released. Then the gain imbalance of the overall system and the power imbalance of 40 channels are compared and the two almost matches, but the significant difference lies on some channels. Finally, the pump power into Raman amplifier is also optimized, and another 1.3 dB improvement of channel equaliza- tion can be further achieved.展开更多
针对高速旋转设备分布式测量需求,设计了一种单通道光纤旋转连接器(FROJ),并进行了性能测试。以此单通道FROJ为基础,采用磁光开关通过时分复用方式设计了四通道FROJ,在静态和动态条件下分别测试了其插入损耗。实验结果表明:该四通道FRO...针对高速旋转设备分布式测量需求,设计了一种单通道光纤旋转连接器(FROJ),并进行了性能测试。以此单通道FROJ为基础,采用磁光开关通过时分复用方式设计了四通道FROJ,在静态和动态条件下分别测试了其插入损耗。实验结果表明:该四通道FROJ的插入损耗小于4.5 d B,旋转变化量小于2 d B,在转速不超过600 r/min时可以实现光信号的可靠传输。展开更多
基金supports from National High Technology 863 Program of China(No.2013AA013403,2015AA015501,2015AA015502,2015AA015504)National NSFC(No.61425022/61522501/61307086/61475024/61275158/61201151/61275074/61372109)+4 种基金Beijing Nova Program(No.Z141101001814048)Beijing Excellent Ph.D.Thesis Guidance Foundation(No.20121001302)the Universities Ph.D.Special Research Funds(No.20120005110003/20120005120007)Fund of State Key Laboratory of IPOC(BUPT)P.R.China
文摘In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.
文摘A practical optical fiber differential pressure sensor is presented at first. Then the techniques of light source feedback, set up of reference channel, proportional measurement and other methods to improve the stability of the system as well as to reduce the interference with same nature are emphatically discussed. Finally, the experiment results of the developed instrument are given.
文摘On the basis of analysis on the temperature monitoring methods for high voltage devices, a new type of fiber optic sensor structure with reference channel is given. And the operation principle of fiber optic sensor is analysed at large based on the absorption of semiconductor chip. The mathematical model of both devices and the whole system are also given. It is proved by the experiment that this mathematical model is reliable.
文摘Information leaks through regular fiber optic communications is possible in the form of eavesdropping on conversations, using standard fiber optic communications as illegal measuring network. The threat of leakage of audio information can create any kind of irregular light emission, as well as regular light beams modulated at acoustic frequencies. For information protection can be used a means of sound insulation, filtration and noising. This paper discusses the technical possibilities of countering threats by monitoring the optical radiation to detect eavesdropping.
文摘光纤通信具有容量大、距离远、抗干扰能力强等优点,是实现高速率、大容量信息传输的技术。低密度奇偶校验(Low Density Parity Check,LDPC)码由于具有良好的纠错性能,可以有效提升光纤通信系统的传输可靠性。为进一步提升该方法的健壮性,文章研究LDPC码的优化设计方法。先深入探讨LDPC码的基本原理及其在光纤通信中的应用,接着提出一种基于密度进化和有限字长效应分析的LDPC码优化方法,并通过光学特性仿真OptSim工具进行了验证。实验结果表明,优化后的LDPC码在不同码长下的误码率均取得了显著降低,特别是在长码字情况下,其纠错性能显著提升。
基金the National Natural Science Foundation of China (60777024)
文摘Optical channel pre-emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s wavelength division multiplexing (WDM) transmission system with three Erbium-doped fiber amplifiers (ED- FAs) and Raman amplifiers concatenated as booster amplifier. The channel imbalance of the overall system changes with different sets of power launched into EDFAs. By appropriately choosing the power input to concatenated EDFAs, the output spectrum of 40 channel signal can be equalized to the most extent. The merit of benefit can be around 5.5 dB by this pre-emphasis equalization. The requirement for the gain equalizer is therefore greatly released. Then the gain imbalance of the overall system and the power imbalance of 40 channels are compared and the two almost matches, but the significant difference lies on some channels. Finally, the pump power into Raman amplifier is also optimized, and another 1.3 dB improvement of channel equaliza- tion can be further achieved.
文摘针对高速旋转设备分布式测量需求,设计了一种单通道光纤旋转连接器(FROJ),并进行了性能测试。以此单通道FROJ为基础,采用磁光开关通过时分复用方式设计了四通道FROJ,在静态和动态条件下分别测试了其插入损耗。实验结果表明:该四通道FROJ的插入损耗小于4.5 d B,旋转变化量小于2 d B,在转速不超过600 r/min时可以实现光信号的可靠传输。