Recently, the GMPLS controlled WSON has emerged as a promising optical transport network. In order to guarantee the optical signal transmission feature without deformation, the optoelectronic 3R regenerators still need to be sparsely placed in the network, termed as translucent networks. The growing size and complexity of the translucent network requires a transition of control plane to move from the traditional centralized model to a fully distributed architecture in the future. However, centrally designed routing, wavelength assignment, and 3R regenerator allocation approaches become unfeasible under the distributed paradigm due to the outdated and inconsistent network state information. A common solution is to accelerate the update frequency of network state, but the fundamental problem remains that the inaccurate state information is still inevitable. Furthermore, it adds a significant increase to the control traffic volume which adversely degrades the performance and scalability of the network control system. In order to mitigate the impact of having inaccurate state information on network performance in the distributed systems, a novel RWA approach is proposed in this paper, termed as routing and distributed wavelength assignment with top ranked probing wavelength set computation. In our proposal, the wavelength assignment is performed by signalling process with a set of carefully preselected probing wavelengths. This set is dynamically computed based on the resource utilization each time the network state is refreshed. The PCE module is adopted in WSON control plane to be responsible for the computation of RWA and 3R allocation. The performance of the proposed approach is studied by extensive simulations. The experiment results reveal that by employing the proposed scheme, without loss on the blocking performance the inaccuracy of the wavelength availability information can be well tolerated, and the set-up delay in lightpath provisioning can be kept at a low level.

This paper presents an elastic optical path network architecture as a novel networking framework to address the looming capacity crunch problem in internet protocol (IP) and optical networks. The basic idea is to introduce elasticity and adaptation into the optical domain to yield spectrally-efficient optical path accommodation, heightened network scalability through IP traffic offloading to the elastic optical layer, and enhanced survivability for serious disasters.

We demonstrate the wavelength trimming of MEMS VCSELs by etching a cantilever-shaped top mirror using FIB etching. The proposed technique can be used for the post-process precise wavelength allocation of athermal MEMS VCSELs. The modeling and experimental results on 850 nm MEMS VCSELs are presented. The results show a possibility of realizing both red-shift and blue-shift wavelength changes by choosing the etching area of the cantilever.

In this paper, a CMOS Class-G supply modulation for polar power amplifiers with high average efficiency and low ripple noise is proposed. In the proposed Class-G supply modulation, the parallel supply modulations which are controlled by switch signals are utilized for low power and high power supplies to increase the average efficiency. A low dropout (LDO) is utilized to suppress the delta-modulated noise and provide a low ripple noise power supply. The proposed supply modulation has high efficiency at large output current as the conventional supply modulation, and it also has high efficiency and low ripple noise at the low output current. To verify the effectiveness of the proposed supply modulation, the proposed supply modulation was designed with 0.13 µm CMOS process. The simulation results show that the proposed supply modulation achieves a maximum efficiency of 85.1%. It achieves an average efficiency of 29.3% and a 7.1% improvement compared with the conventional supply modulations with Class-E power amplifier. The proposed supply modulation also shows an excellent spurious free dynamic range (SFDR) of -73 dBc for output envelope signal.

In next-generation networks, ultra-high speed transfer capability will become necessary to support a variety of advanced multimedia services. The Optical Wavelength Division Multiplexing (WDM) network is seen as one of promising networks. To deal with various multimedia services, the network should support not only unicast transmission but also multicast transmission. However, IP multicast has several problems, for example, all routers must have multicast functions. IP multicast needs routers with high overheads and excessive energy consumption. Hence, optical multicasting in optical WDM networks is a promising solution for future internet services. A tree-shared multicasting concept has been proposed to support multicast transmissions in optical WDM networks. This method assembles multiple multicast traffic streams into one burst and the burst is delivered using a shared-tree. However, this method can not be applied to dynamic multicasting. This paper proposes a novel WDM multicast design method for dynamic traffic demand using multiple shared-trees, which includes shared-tree generation/selection and wavelength assignment, for the purpose of simplifying the routing process and receiving multicast traffic efficiently. We evaluate its performance from the viewpoints of the burst loss probability and the number of redundant and useless transfers whose data is discarded at the egress edge nodes.

A Wavelength division multiplexing passive optical network (WDM-PON) system that uses spectrum-sliced broadband incoherent light is attractive because it avoids the cost of operating/administering wavelengths in optical network units (ONU) at customer premises. However, it is difficult to enhance the spectrum efficiency to ensure a sufficient signal to noise ratio because it would demand broad channel width. To overcome this problem, we proposed a spectrum-interleaved duplex technique. It enables upstream and downstream communications to share one channel by using a cyclic filter. This sharing of one channel eliminates the need for a guard interval between signal lights duplexed in the channel. One residual issue regarding single band transmission is its robustness to reflection in the transmission medium. To increase the reflection robustness of the spectrum-interleaved duplex scheme, we propose a reflection remover based on an optical code division multiplexing technique. We also evaluate the extent to which capacity of the spectrum efficiency of the spectrum-interleaved duplex WDM-PON system that uses spectrum-sliced broadband incoherent light can be increased.

The design of an energy-efficient wavelength division multiplexing (WDM) transponder is proposed and effectiveness of the proposed WDM transponder is experimentally studied. The proposed WDM transponder interworking with the link-aggregation technique possessed by a layer 2 switch can achieve power saving depending on traffic volume variations by utilizing an adaptive interface control. Monitoring methods for the link connectivity of a sleep link are also discussed.

A bidirectional amplification module has been proposed for use in IP-over-CWDM networks. The module is based on a bidirectional erbium-doped fiber amplifier. The loss compensation characteristics of the module obtained in a bidirectional IP transmission experiment confirmed that the losses of the optical node and the transmission fiber in the network can be compensated for effectively by the module making it possible to increase the number of nodes and the total fiber length of the network.

We propose a mechanism called “optical plug and play” for constructing GMPLS networks automatically. It offers lower operation effort and fast network construction, and avoids misconfiguration. Optical plug and play architecture has its procedure, a link-up search mechanism for OXCs, network and node architectures to realize optical plug and play, and an LMP extension to exchange the information between nodes necessary for identifying adjacent nodes. We implement prototypes of both OXCs and routers that support the optical plug and play proposal. Simulations and experiments confirm its performance and feasibility.

A loop-back WDM-PON based on a RSOA has lots of merits, however one-level of the upstream signal has downstream information under OOK modulation. These effects make difficult to define decision threshold and estimate BER. In order to solve this, we propose a mathematical model of remodulated OOK signal and experimentally demonstrate BER performance with the near optimum decision threshold achieved by the proposed model.

We investigate the problem of switch port allocation in WDM networks that use the hybrid optical-electronic switching node architecture. The objective is to support given traffic demands while minimizing the number of electronic switch ports used, or equivalently minimizing the number of established lightpaths. We first formulate the problem as a mixed integer linear programming (MILP) problem. However, due to the high computational complexity of exact optimization, we develop a simulated annealing (SA) algorithm to get an approximate solution. Results from the SA algorithm demonstrate that, compared to the optical-electrical-optical (O-E-O) node architecture, a WDM network that employs the hybrid switching node architecture requires many fewer lightpaths. We also develop a lightpath assignment heuristic which requires much less computation time than the SA algorithm while maintaining close objective values. The lightpath assignment heuristic is used to investigate the switch port allocation behaviors. Simulation results show that nodes with high degrees or with small average node distances require large numbers of optical switch ports. Moreover, nodes with large amounts of terminate (originated/destined) traffic require large numbers of electronic switch ports. Since the lightpath assignment heuristic requires small computation time, it can be used in the network design process in which a large number of network scenarios must be considered.

The popularity of cloud computing services is driving the boom in building mega-datacenters. This trend is forcing significant increases in the required scale of the intra-datacenter network. To meet this requirement, this paper proposes a photonic network architecture based on a multi-layer hypercube topology. The proposed architecture uses the Cyclic-Frequency Arrayed Waveguide Grating (CF-AWG) device to realize a multi-layer hypercube and properly combines several multiplexing systems that include Time Division Multiplexing (TDM), Wavelength Division Multiplexing (WDM), Wave-Band Division Multiplexing (WBDM) and Space Division Multiplexing (SDM). An estimation of the achievable network scale reveals that the proposed architecture can achieve a Peta-bit to Exa-bit class, large scale hypercube network with existing technologies.

This paper describes recent developments of photonic crystal fibers (PCFs), which can realize ultra wide-band transmission or large Aeff, as well as photonic crystal multi-core fibers (PC-MCFs), which have large potentials as future high-capacity transmission lines using Space Division Multiplexing.

We propose a scheme of MultiCast Routing and Wavelength Assignment (MC-RWA) to establish light-tree for dynamic multicast session for the Wavelength Division Multiplex (WDM) network by choosing the wavelength that leads to a reduction in blocking probabilities by using a parameter Δ. Δ is defined as the overall reduction of connectivity of the nodes in the network caused by a wavelength assignment process when using a particular wavelength, and we assign wavelength resources to the multicast session by choosing the Δ which leads to smallest reduction in connectivity. Through computer simulation, we show that the proposed scheme has lower blocking probabilities when compared with minimum cost scheme under the condition that wavelength conversion is not allowed.

Quantum key distribution (QKD) systems can generate unconditionally secure common keys between remote users. Improvements of QKD performance, particularly in key generation rate, have been required to meet current network traffic. A high-speed QKD system should be equipped with low-loss receivers with high visibility, highly efficient photon detectors with small dark count probability. A solution to these issues is to employ planar lightwave circuit (PLC) interferometers, single photon detection circuits and modules, together with multi-wavelength channels transmission using wavelength division multiplexing (WDM) technique.

We propose a high-speed protection scheme for multiple-priority-class traffic transmission in WDM ring networks. This scheme achieves high-speed protection by quickly suspending transmission of low-priority traffic when a failure is detected. Each node suspends transmission of the low-priority traffic being sent over the backup path corresponding to the impaired primary path after receiving a failure notification and checking a table that includes the primary paths passing through the node, the backup paths corresponding to the primary paths, and low-priority traffic transmitted by the node. If a node detects a failure, it sends a single failure notification for each ring to the source node of the primary path, and the nodes on the route sequentially suspend low-priority traffic. Simulation shows that the proposed scheme reduces the failure-recovery time by up to 60% compared with the conventional scheme.

We present our proposed designs of optical access architecture based on WDM technology toward new-generation networks for two types of topologies: Single-star (SS) and passive-double-star (PDS). We adopt the concept of WDM-direct which links multiple wavelengths to each optical network unit (ONU). Our proposed architecture based on WDM-direct can achieve more than 10 Gbps access per ONU. Moreover, our architecture can provide not only conventional bandwidth-shared services but also bandwidth-guaranteed services requiring more than 10 Gbps bandwidth by establishing end-to-end lightpaths directly to each ONU, and thus meet high requirements of QoS in new-generation networks. Firstly, we show our proposed designs of SS-type architecture, and experimentally demonstrate the system. We confirm that the optical line terminal (OLT) successfully switches between packet/lightpath data transmissions for each ONU. In addition, we measure and evaluate optical power loss in upstream/downstream transmissions between the OLT and ONUs. Secondly, we show our proposed designs of PDS-type architecture, and theoretically analyze and evaluate the bit-rate capacity of the system.

We propose the network on demand concept to yield the optical access network system that well handles the diversity in user demands and support technologies such as module and devices configuration. In this proposal, the network accommodation equipment, such as OLT needed for each service, is installed ‘virtually' using WDM, and the physical rate can adapt to the user-demanded service rate by using the WDM parallel transmission technique. It well handles the diversity in user demands/services and lowers system power consumption.

In this paper, we demonstrate a 10.66 Gb/s bidirectional TDM over long-reach WDM hybrid PON supported by distributed Raman amplification, and the power budget margin is measured to be 15 dB for downstream transmission and 12 dB for upstream transmission, with dual Raman pump power of 300 mW.

While the problem of multicast routing and wavelength assignment (MC-RWA) in optical wavelength division multiplexing (WDM) networks has been investigated, relatively few researchers have considered network survivability for multicasting. This paper provides an optimization framework to solve the MC-RWA problem in a multi-fiber WDM network that can recover from a single-link failure with shared protection. Using the light-tree (LT) concept to support multicast sessions, we consider two protection strategies that try to reduce service disruptions after a link failure. The first strategy, called light-tree reconfiguration (LTR) protection, computes a new multicast LT for each session affected by the failure. The second strategy, called optical branch reconfiguration (OBR) protection, tries to restore a logical connection between two adjacent multicast members disconnected by the failure. To solve the MC-RWA problem optimally, we propose an integer linear programming (ILP) formulation that minimizes the total number of fibers required for both working and backup traffic. The ILP formulation takes into account joint routing of working and backup traffic, the wavelength continuity constraint, and the limited splitting degree of multicast-capable optical cross-connects (MC-OXCs). After showing some numerical results for optimal solutions, we propose heuristic algorithms that reduce the computational complexity and make the problem solvable for large networks. Numerical results suggest that the proposed heuristic yields efficient solutions compared to optimal solutions obtained from exact optimization.