Hybrid WDM/TDM PON system employing an all-optical wavelength converter

A new hybrid WDM/TDM passive optical network （PON） implemented by using all-optical wavelength converters （AOWCs） is proposed. The AOWCs are based on the cross-gain modulation （XGM） effect of the semiconductor optical amplifier （SOA）. Moreover, the feasibility of this sys- tem is experimentally demonstrated by evaluating the impacts of the optical wavelength conversion, time domain waveforms, eye diagrams and bit-error-rate （BER） in AOWC. The results show that the proposal will be a promising solution for the next generation access networks.

Wavelength Converter Information Sharing in GMPLS Controlled Optical Networks

Wavelength converters are used in optical networks to overcome transparent wavelength channel insufficiency. However, current GMPLS control plane does not distribute wavelength con- verter information to network nodes. To overcome this situation, four wavelength converter information sharing methods for GMPLS-controUed optical networks are proposed. The first two, Conversion Capability during Signaling （CCS） and Conversion Availability during Signaling （CAS）, are based on the RSVP-TE signaling protocol, while the others, Conversion Capability Advertisement （CCA） and Conversion Availability Advertisement （ CAA ） , are based on the OSPF-TE routing protocol. Simulations show that CAA obtains the lowest blocking, while CCS the highest. Moreover, CAA only slightly increases the control plane load compared to CAS.

Broad-Band All-Optical Wavelength Conversion of Differential Phase-Shift Keyed Signal Using an SOA-Based Nonlinear Polarization Switch

Broad-band all-optical wavelength conversion of differential phase-shift keyed （DPSK） signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a semiconductor optical amplifier （SOA） based nonlinear polarization switch. A wavelength converter for the 10 G b/s DPSK signal is presented, which has a wide wavelength range of more than 30 nm. The converted signals experience small power penalties less than 1.4 dB compared with the original signal, at a bit error rate of 10-9. Additionally, the optical spectra, the measured waveforms and the open eye diagrams of the converted signals show a high quality wavelength conversion performance.

All optical wavelength converter and its application in optical network

All optical network （AON） is a hot topic in recent studies of optical fiber communications. Key techniques in AON include optical switching/routing, optical cross connection （OXC）, all optical wavelength conversion （AOWC）, all optical buffering, etc. Opti- cal switching/routing is in fact wavelength switching/ routing. OXC and wavelength conversion （WC） are introduced into cross nodes so that a virtual wavelength path is established. With WC, communication route is formed only if there is unused wavelength in an individual segment link. The rate wavelength usage is thus greatly increased. The blocking rate of network can be reduced by adding WCs, especially for huge capacity multiple nodes ones. Therefore, WC has attracted much attention in basic research of optical communication and is used in some experimental networks.This dissertation studies all optic wavelength conversion and its application, with the contributions in the following five aspects.

OPTIMIZATION OF WDM OPTICAL PACKET SWITCHES WITH SPARSE WAVELENGTH CONVERTERS AND NON-DEGENERATE FIBER DELAY-LINES

This paper investigates the untraditional approach of contention resolution in Wavelength Division Multiplexing (WDM) Optical Packet Switching (OPS). The most striking characteristics of the developed switch architecture are: (1) Contention resolution is achieved by a combined sharing of Fiber Delay-Lines (FDLs) and Tunable Optical Wavelength Converters (TOWCs); (2) FDLs are arranged in non-degenerate form, i.e., non-uniform distribution of the delay lines; (3) TOWCs just can perform wavelength conversion in partial continuous wavelength channels, i.e., sparse wavelength conversion. The concrete configurations of FDLs and TOWCs are described and analyzed under non-bursty and bursty traffic scenarios. Simulation results demonstrate that for a prefixed packet loss probability constraint, e.g., 10-6, the developed architecture provides a different point of view in OPS design. That is, combined sharing of FDLs and TOWCs can, effectively, obtain a good tradeoff between the switch size and the cost, and TOWCs which are achieved in sparse form can also decrease the implementing complexity.

Performance Evaluation of Wavelength Division Multiplexing Photonic Analogue-to-Digital Converters for High-Resolution Radar Systems

The performance of the wavelength division multiplexing (WDM) photonic analogue-to-digital converter (ADC) used for digitization of high-resolution radar systems is evaluated numerically by using the peak signal-to-noise ratio (SNR) metric. Two different WDM photonic ADC architectures are considered for the digitization of radar signals with 5 GHz of bandwidth (spatial resolution of 3 cm), in order to provide a comprehensive study of the compromises present when deploying radar signals with high-resolution: 1) a four-channel architecture with each channel employing an ADC with 5 GSamples/s, and 2) an eight-channel architecture with each channel employing an ADC with 2.5 GSamples/s. For peak powers of the pulsed source between 10 and 20 dBm and a distance between the radar antenna and the sensing object of 2.4 meters, peak SNR levels between 29 and 39 dB are achieved with the eight-channel architecture, which shows higher peak SNR levels when compared with the four-channel architecture. For the eight-channel architecture and for the same peak powers of the pulsed source, peak SNR levels between 11 and 16 dB are obtained when the distance increases to 13.5 meters. With this evaluation using the peak SNR, it is possible to assess the performance limits when choosing a specific radar range, while keeping the same resolution.

Silicon-Based Mode Converter and Demultiplexer for Wavelength Division Multiplexing Transmission by Using Multimode Interference Couplers

We present a mode converter and demultiplexer structure for wavelength division multiplexing (WDM) transmission by employing multimode interference (MMI) on Silicon-on-Insulator (SOI) platform. The mode converter and demultiplexer have a compact size of less than 2.7 μm × 43.7 μm. Moreover, the crosstalk between neighboring wavelength channel within C band (1530 nm to 1570 nm) can be reduced by utilizing the tapered phase shifter cascaded with MMI. The simulated results indicate that this structure has a low insertion loss of less than 1 dB, a low crosstalk of better than ?15 dB and a relatively high fabrication tolerance of ~10 nm. Such structure may find many potential applications in silicon photonic integrated devices.

Research on Fault Repair Method of All-Optical Network Based on SDN

All-optical network,as a new backbone network,is featured with high speed and large capacity transmission.It may be out of order due to various faults while providing high-performance transmission service,thus more effective fault repairing methods are required.A routing and wavelength assignment method based on SDN is designed and analyzed from the perspective of service function chaining in this paper.A multi-objective integer linear programming model based on impairment-aware and scheduling time is constructed by combining the unified control of control plane with the resource allocation mode of service function virtualization.Meanwhile,an improved Firefly Algorithm is adopted to solve the model for obtaining a better scheduling scheme,so as to the resources are allocated on-demand in a more flexible and efficient way,which effectively improved the self-recovery capability of the network.In the simulation experiments,Through the comparison between the method proposed and methods based on centralization and distribution,method proposed in the paper is superior to the compared ones in the indexes of survivability,blocking probability,link recovery time,and presents a better scheduling performance,makes the system has stronger ability of self-healing in the face of failure.

Blocking Probability in All-Optical WDM Network Using IMCA

The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced analytical model is proposed to evaluate the blocking performances in topology network and to improve the performances of reduction of blocking probability. The variation of probability is based on the wavelength and load used in the network. The conversion is carried out with the support of optical backbone of the inherent flexibility of the network using the proposed IMCA in Sparse-Partial Wavelength Conversion (SPWC) architecture. It reduces the number of converters significantly with efficient process and provides placement scheme of wavelength converters in the network. The proposed model utilizes the network with the assignment and routing of wavelength using dynamic process of assignment algorithm. The proposed model provides dynamic and static routing process with the range limit to have a minimum conversion for the same probabilities of blocking. The proposed system analysis and the simulation results show the better performances in faster coverage, minimum number of conversions, blocking probability improvement for high load.

A novel 40-Gb/s all-optical inverted wavelength converter based on a modified terahertz optical asymmetric demultiplexer

A novel scheme for all-optical inverted wavelength conversion with 40-Gb/s pseudorandom bit sequences (PRBSs) based on a modified terahertz optical asymmetric demultiplexer (TOAD) is proposed. The performance of the proposed wavelength converter is analyzed in term of extinction ratio (ER) through numerical simulations. For a typical ER of 10 dB, some key characteristic parameters of the semiconductor optical amplifier (SOA) are designed. With the properly designed parameters, a high quality eye diagram is achievable, indicating that the amplitude fluctuation of the output signal is effectively reduced.

Performance analysis of optical burst switching node with limited wavelength conversion capabilities

The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.

Towards 640 Gbit/s wavelength conversion based on nonlinear polarization rotation in a semiconductor optical amplifier

Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation （NPR） in a single semiconductor optical amplifier （SOA） and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio （ER） on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.

A High Efficiency Wavelength Conversion Scheme Based on Four Wave Minxing in a Semiconductor Optical Amplifier

A new approach of all optical wavelength converter based on four wave mixing (FWM) in a semiconductor optical amplifier (SOA) with the conjugate wave reflected by a fiber Bragg grating (FBG) and then amplified by the SOA is reported. By adjusting the pump power, the conversion efficiency could be improved 7～10dB with signal to background noise ratio (SBR) deteriorated 1～2dB, compared with traditional single pump four wave mixing.

A Novel All-Optical Analog-to-Digital Converter

An all-optical analog-to-digital converter capable of sampling at 50GS/s is described. The ADC works in the frequency domain. The RF signal is sampled by electro-optically steerable gratings and quantized by a set of detectors with scalable apertures.

Mathematical Model for Dynamic Pump-Wavelength Selection Switch

This paper presents a mathematical model based on dynamic pump-wavelength selection for an optical packet switch (OPS). In the OPS, multiple packets that carry the same wavelength from different input ports could be addressed to the same output port at the same time slot. This condition is called wavelength contention. Of those contended packets, only one is forwarded to the output fiber while the others are dropped. Parametric wavelength conversion is used to convert the contended wavelengths into available non-contending wavelengths. The OPS based on the dynamic pump-wavelength selection scheme, where the pump-wavelengths are adjusted based on the requests in every time slot, uses a heuristic matching algorithm to minimize the number of packet losses. However, there is no guarantee that the heuristic algorithm outputs the optimum result. The mathematical model presented in this paper is used to confirm the performance of the heuristic matching algorithm for the DPS-based OPS. A simulation shows that the heuristic matching algorithm achieves the same performance as the optimum solution provided by the mathematical model.

Wavelength Routing Algorithmof All Optical Network Based on Traffic Engineering

General multi-protocol label switching(GMPLS) based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.

Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system

An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential quadrature phase shift keyed(DQPSK), and non-return-to-zero(NRZ) is proposed. The noise tolerances of different modulation formats are analyzed, and the optimal input power ratio between phase and intensity modulation formats for the best overall receiving performance is investigated under unchanged total input power. Moreover, this scheme can seamlessly coexist with the traditional WDM channel.

All-Optical Wavelength Conversion With Multi-Channel Broadcasting at 10 Gb/s Using an Electroabsorption Modulator

All-optical wavelength conversion has been demonstrated with an electroabsorption modulator based on cross-absorption modulation. For the first time, simultaneous broadcasting up to 6 different wavelengths at 10Gb/s is obtained with less than 0.5-dB polarization dependence.

Polarization and wavelength routers based on difractive neural network

In the feld of information processing,all-optical routers are signifcant for achieving high-speed,high-capacity signal processing and transmission.In this study,we developed three types of structurally simple and fexible routers using the deep difractive neural network(D2 NN),capable of routing incident light based on wavelength and polarization.First,we implemented a polarization router for routing two orthogonally polarized light beams.The second type is the wavelength router that can route light with wavelengths of 1550,1300,and 1100 nm,demonstrating outstanding performance with insertion loss as low as 0.013 dB and an extinction ratio of up to 18.96 dB,while also maintaining excellent polarization preservation.The fnal router is the polarization-wavelength composite router,capable of routing six types of input light formed by pairwise combinations of three wavelengths(1550,1300,and 1100 nm)and two orthogonal linearly polarized lights,thereby enhancing the information processing capability of the device.These devices feature compact structures,maintaining high contrast while exhibiting low loss and passive characteristics,making them suitable for integration into future optical components.This study introduces new avenues and methodologies to enhance performance and broaden the applications of future optical information processing systems.

All-Optical Wavelength Conversion with Amplitude Equalization and Pulse Shaping

A dual-wavelength-injection-locked (DWIL) Fabry-Perot (FP) laser is used as an all-optical wavelength converter and regenerator. Regenerated pulses have narrower pulse-width of 37ps. Power penalty and extinction-ratio improvement of 1.5dB and 4dB respectively were achieved.