Research on fault location technology based on BP neural network in DWDM optical network

BP neural network is introduced to the fault location field of DWDM optical network in this paper. The alarm characteristics of the optical network equipments are discussed, and alarm vector and fault vector diagrams are generated by analyzing some typical instances. A 17 × 14 × 18 BP neural network structure is constructed and trained by using MATLAB. By comparing the training performances, the best training algorithm of fault location among the three training algorithms is chosen. Numerical simulation results indicate that the sum squared error （SSE） of fault location is less than 0.01, and the processing time is less than 100 ms. This method not only well deals with the missing alarms or false alarms, but also improves the fault location accuracy and real-time ability.     

Improvement of normalized throughput in WDM ＋ OCDMA system using optical hard-limiters

Recently,because of advantages of high-speed opticalprocessing and si mple network control ,the optical codedivision multiple access (OCDMA) has become a hotscheme in LAN and access network[1-5]. According tothe spreading mode, OCDMAcan be mainly dividedi…     

Design of buffer structure at core nodes in optical burst switching

DrivenbybothpromptincreaseofIPserviceandvast bandwidthofWDM,conventionalopticalnetworksareevolvingintothenextgenerationopticalInternet(NGOI).Somefunctionsofconfiguration,performance andfaultmanagement,executedinelectronicdomainatpresent,willbeshiftedintoo…     

Novel algorithm of finding good candidate pre-configuration cycles in survivable WDM mesh network

Pre-configuration Cycle (p-cycle) is a promising ap-proach for protecting working capacities in WDMnet-works because of its ability to achieve ring-like recoveryspeed while maintaining the capacity efficiency of amesh-restorable network[1].The first and t…     

Statistical characteristics and effects of polarization mode dispersion in dispersion managed soliton systems

Recently,the dispersion-managed solitons(DMS) areof great interest in soliton communication systems .Be-cause of some prior advantages compared with conven-tional solitons ,such as higher pulse energy and signalnoise ratio,lower averaged dispersionline an…     

Threshold level and gain of forward stimulated Brillouin scattering in a forward pumped s-band discrete DCF fibers Raman amplifier

Recently,with fast developing of extra-capacity of fi-ber communication experi mental systems ,dense wave-length division multiplexing (DWDM) technology hasbeen adopted widely[1-3].Now,1300 nmband and 1550nmband have been connected with each other to be a…     

Box-like spectral response of a series-coupled microring resonant filter in a parallel channel

Inthelast decades ,microring resonator( MRR) wave-lengthfilters are developed rapidly because of their po-tential applications in wavelength division multiplexing( WDM) communicationsystems andtheir excellent fea-tures includingfunctionality,compactness a…     

Simulation of chaotic synchronization communication system based on incoherent optical feedback and injection

Chaotic communicationis of great interest because ofa potential applications in secure communications andspread spectrumcommunications .Asemiconductor lasersubject to optical feedback is known to have complexdynamic behavior ,and it can produce chaotic wa…     

Narrow-channel-spacing 32-channel AWG multiplexer with an innovative alignment method

A 32-channel 50 GHz spaced arrayed-waveguide grating（AWG） with our innovative configuration has been designed and fabricated. The performance of the device has been fully tested by using a system that consists of a tunable laser light source （TLS）, an optical power meter and a polarization controller. The insertion loss （IS） of the device is 4.2-7.4 dB. The crosstalk is about - 28 dB. The IS uniformity is less than 3.3 dB. With our configuration,the performance of the device has been enhanced effectively and the difficulty in alignment process has been decreased obviously.     

New scheme of optical switch technology of time division

Intheopticalnetwork,opticalswitchcanrealizethe signaltransformandswitchinopticalfield.Thetechnol ogyincludeswavelengthdivisionandtimedivision.Thetimedivisionswitchisthebestsolution,whileitisdiffi culttoberealized,especiallyforthelargescaleandlittle timesl…     

Pulse-width compression based on photonic crystal fiber

Since the first PCF was fabricated in 1996 ,PCF hasattractedthe significant attention due toits unique char-acteristics . One of the highlights is that ,according tothe flexibility of conveniently changing the core area ofPCF,a smaller mode-field area can…     

Generation of low jitter and discrete tunable dual-wavelength optical pulses at arbitrary repetition rates

Recently there is an increasing interest in generatingshort optical pulses with lowti ming jitter and tuneablemulti-wavelength due toitsi mportant applicationin op-tical ti me division multiplexed(OTDM),wavelength di-vision multiplexed(WDM)systems,and opt…     

Studies of the correction for phase diverse speckle

Phase diverse speckle is a novel kind of imaging technique and can be used to overcome image degradation from unknown phase aberrations, such as atmospheric turbulence. The wave-front phase expanded on the Zernike polynomials is esti- mated from a pair of images (in the focal and out of focus planes). In this paper the principle of PDS is analyzed, and genetic algorithm is used as the iterative algorithm to simulate some characteristics, such as the influence of Zernike polynomials’ mode, amplitude of turbulence on the phase estimation. Thus, a new method for recovery of images is explored.     

Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms, so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors, and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system, so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the fre- quency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the fre-quency characteristics.     

Teleportation of an arbitrary unknown N -qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers（M 〈 N） is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home- Zeilinger （GHZ） state and N-M non-maximally entangled Einstein-Podolsky-Rosen （EPR） pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Linearity optimization of edge filter demodulators in FBGs

A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBG .By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators has been broadened effectively, and the requirement of optical filter＇s linear range has been reduced. Theoretical analyses and the simulation results indi-cated that the linear range of optimized edge fdter demodulator＇s covers the whole transition region of the edge filter, while a strict linearity of the optical filter is not necessary.     

Theoretical research on light propagation in W-type single-mode fiber

We give the characteristic equation of a W-type fiber by solving Maxwell＇s equations along with boundary conditions at the interfaces. The cutoff condition of the fundamental mode is examined, and a novel W-type fiber working in S-band is designed.     

Reconstruction of strain distribution in fiber Bragg gratings with differential evolution algorithm

Differential evolution algorithm is used to solve the inverse problem of strain distribution in fiber Bragg grating （FBG）. Linear and nonlinear strain profiles are reconstructed based on the reflection spectra. An approximate solution could be obtained within only 50 rounds of evolutions. Numerical examples show good agreements between target strain profiles and reconstructed ones. Online performance analysis illuminates the efficiency and practicality of differential evolution algorithm in solving the inverse problem of FBG.     

Quality improvement of the dual-wavelength signals in DLOB via power equalization

The data packet buffering can be implemented in dual loop optical buffer (DLOB) through cross-phase modulation (XPM) between the control signal and the data packets. However,the output equality of dual wavelength signals will degrade due to the unbalanced gain and phase shift. This problem can be resolved by power equalization using the saturation character-istics of SOA. The data packets with 2.5 Gb/s can be buffered in DLOB for 16 cycles corresponding to 16.5 μs.The extinction ratio of the output packet is 8 dB while the S/N is 8.1 dB.