This paper considers wide-sense nonblocking operation of the Wavelength-Space-Wavelength elastic optical switch. Six control algorithms, based on functional spectrum decomposition in interstage links and functional decomposition of center stage switches, are proposed for two switching fabric architectures. For these algorithms we derived wide-sense nonblocking conditions and compared them with strict-sense nonblocking ones. The results show that the proposed algorithm reduces the required number of frequency slot units (FSUs) or center stage switches, depending on the switching fabric architecture. Savings occur even when connections use small number of frequency slot units.

IoT (Internet of Things) services are emerging and the bandwidth requirements for rich media communication services are increasing exponentially. We propose a virtual edge architecture comprising computation resource management layers and path bandwidth management layers for easy addition and reallocation of new service node functions. These functions are performed by the Virtualized Network Function (VNF), which accommodates terminals covering a corresponding access node to realize fast VNF migration. To increase network size for IoT traffic, VNF migration is limited to the VNF that contains the active terminals, which leads to a 20% reduction in the computation of VNF migration. Fast dynamic bandwidth allocation for dynamic bandwidth paths is realized by proposed Hierarchical Time Slot Allocation of Optical Layer 2 Switch Network, which attain the minimum calculation time of less than 1/100.

In all-optical switches using the cascade of second harmonic generation and difference frequency mixing in periodically poled lithium niobate (PPLN) waveguide devices, walk-off between the fundamental and second harmonic pulses causes crosstalk between neighboring symbols, and limits the switching performance. In this paper, we numerically study retiming characteristics of all-optical switches that employ the PPLN waveguide devices with consideration for the effects of the crosstalk and for the input timing of the data and clock pulses. We find that the time offset between the data and clock pulses can control the timing jitter of the switched output; an appropriate offset can reduce the jitter while improving the switching efficiency.

We propose an optical switch control procedure for the Active Optical Access System (AOAS). Optical switches are used in AOAS instead of optical splitters in PON. In the proposed procedure, an OLT determines the switching schedules of optical switches on OSW (Optical Switching Unit) which is installed between OLT and ONU, and informs the OSW of them with a switch control frame preceding of data frame transmission. Then the switch controller on OSW controls the optical switches based on the switching schedules. We developed the prototype systems of OSW, OLT, and ONU. We implemented the optical switch control function with logic circuits on the prototype systems. We demonstrate the proposed procedure works effectively with logic circuits. We also evaluate the 10 Gps optical signal transmission between OLT and ONU. We demonstrate the receiver sensibility on OLT and ONU achieves the distance of 40 km for optical signals transmission with FEC (Forward Error Correction). These receivers are applicable for both AOAS and 10G-EPON.

Vertically stacked optical banyan (VSOB) is an attractive architecture for constructing banyan-based optical switches. Blocking behaviors analysis is an effective approach to studying network performance and finding a graceful compromise among hardware costs, blocking probability and crosstalk tolerance; however, little has been done on analyzing the blocking behavior of VSOB networks under crosstalk constraint which adds a new dimension to the switching performance. In this paper, we study the overall blocking behavior of a VSOB network under various degree of crosstalk, where an upper bound on the blocking probability of the network is developed. The upper bound depicts accurately the overall blocking behavior of a VSOB network as verified by extensive simulation results and it agrees with the strictly nonblocking condition of the network. The derived upper bound is significant because it reveals the inherent relationship between blocking probability and network hardware cost, by which a desirable tradeoff can be made between them under various degree of crosstalk constraint. Also, the upper bound shows how crosstalk adds a new dimension to the theory of switching systems.

In Optical Burst Switched (OBS) networks, packets are assembled into bursts at ingress edge routers and disassembled at egress edge routers. This letter presents an analytical model to quantify the burstification latency in the OBS networks. To the authors' best knowledge, this letter is the first one to address the latency issue in OBS in a comprehensive manner analytically. The results allow us to quantitatively understand how OBS network parameters such as maximum burst length and maximum timeout affect the packet latency in the OBS networks. We show that the burstification latency in the OBS network is bounded and can be tuned by setting the system parameters under latency constraints.

We studied a silicon (Si) waveguide using ferro-electric liquid crystal (FLC) cladding for various applications in optical networks. The FLCs in the cladding layer change their effective refractive index corresponding to the applied voltage polarity, and give a phase shift to the traveling lightwave in the waveguides. The phase change coefficients of three-layer slab waveguides with FLC/Si/SiO2 structure were calculated. We observed an amplitude change in the output light of an experimental modulator consisting of a Mach-Zehnder interferometer with FLC-cladding Si-rib waveguides on a silicon-on-insulator wafer, and evaluated the phase shift at a wavelength of 1550 nm. We propose optical switching devices using Si-rib waveguide Mach-Zehnder interferometers having FLC cladding. Switching of experimental devices operating at 1550 nm wavelength was demonstrated.

We study the configuration issue of three-stage multi-granularity optical cross-connects (MG-OXC) for the dynamic traffic model in all-optical networks. From the single node point of view, we propose a configuration algorithm to configure different granularity cross-connects for arrival sub-requests with different traffic types and bandwidths. The performance of the configuration algorithm is evaluated by simulation and, furthermore, is validated by experiment based on our flexible Multi-functional Optical Switching Testbed (MOST).

Ultrafast all-optical switching was experimentally demonstrated using four-wave mixing in an SOA. Two pump pulses with different wavelengths and timings were used for 12 switching. The cross-correlation measurements of FWM signals using a short reference pulse show the high-speed switching capability for wavelength routing in OTDM networks.

Ultrafast all optical switching using pulse trapping by 100 fs ultrashort soliton pulse across zero dispersion wavelength is investigated. The characteristics of pulse trapping are analyzed both experimentally and numerically. Using the pulse trapping, 1 THz ultrafast all optical switching is demonstrated experimentally. Arbitral one pulse is picked off from pulse train. Pulse trapping for CW signal is also demonstrated and ultrashort pulse is generated by pulse trapping. From these investigation, it is shown that ultrafast all optical switching up to 2 THz can be demonstrated using pulse trapping.

We describe the characteristics of all-optical switching schemes based on semiconductor optical amplifiers (SOAs), with particular emphasis on the role of the fast carrier dynamics. The SOA response to a single short pulse as well as to a data-modulated pulse train is investigated and the properties of schemes relying on cross-gain as well as cross-phase modulation are discussed. The possible benefits of using SOAs with quantum dot active regions are theoretically analyzed. The bandfilling characteristics and the presence of fast capture processes may allow to reach bitrates in excess of 100 Gb/s even for simple cross-gain modulation schemes.

Vertical stacking is a novel technique for building switching networks, and packing multiple compatible connections together is an effective strategy to reduce network hardware cost. In this paper, we study the crosstalk-free permutation capability of an optical switching network built on the vertical stacking of optical banyan networks to which packing strategy is applied. We first look into the nonblocking condition of this optical switching network. We then study the crosstalk-free permutation in this network by decomposing a permutation evenly into multiple crosstalk-free partial permutations (CFPPs) and realizing each CFPP in a stacked plane of the network such that a crosstalk-free permutation can be performed in a single pass. We present a rigorous proof of CFPP decomposability of a permutation and also a complete algorithm for CFPP decomposition. The possibility of a tradeoff between the number of passes and the number of planes required for realizing a crosstalk-free permutation in this network is also explored in this paper.

We propose and describe a free-space optical interconnection device with a photorefractive semi-linear resonator. The hologram in the photorefractive crystal is, in general, volatile and the erasing of it coincides with the diffraction of the signal beam. Therefore we have to reform the hologram again after several transmissions of the data or use some fixing techniques such as thermal fixing and electrical fixing. In our interconnection device, the hologram is enhanced by the feedback beam that is a part of the input signal divided by the beam splitter within semi-linear resonator, therefore the sustentation time of the connection can be extended. We explain the sustentation mechanism and investigate the optimum reflectivity of the beam splitters, which determine the feedback rate of the input signal, within feedback circuit for the high output conversion efficiency. We also analyze the coupling strength threshold for sustentation of the connection. We give a basic experiment on 33 interconnection by using BaTiO3 crystal and Ar+ laser whose wavelength is 514 [nm]. We show that the connections are held for long time without the continuous illumination of the control beam.

The authors have established new switching architecture of all optical WDM network suitable for the application of video transmission. In this paper, emphasis is put on a setup of a wavelength connection based on contiguous wave-band pool and we have proposed new Wave-Band Routing and Assignment (WBRA) method which provides simple switching and high speed wavelength assignment. Assuming the environment without wavelength convertor, our wave-band switching scheme is applied to several network topologies for performance evaluation. Then effectiveness and feasibility of this scheme are confirmed from a viewpoint of the number of required wavelengths. Simulation results indicate that our proposal scheme attains lower number of required wavelengths as compared to the fixed wave-band scheme. Assuming to use wavelength convertors, we have also evaluated the situation that the number of hops is restricted.

The OptIPuter is a radical distributed visualization, teleimmersion, data mining and computing architecture. Observing that the exponential growth rates in bandwidth and storage are now much higher than Moore's Law, this major new project of several universities--currently six in the US and one in Amsterdam--exploits a new world of computing in which the central architectural element is optical networking. This transition is caused by the use of parallelism, as in supercomputing a decade ago. However, this time the parallelism is in multiple wavelengths of light, or lambdas, on single optical fibers, creating a LambdaGrid. Providing applications-centric middleware to control the LambdaGrid on a regional and global scale is a key goal of the OptIPuter and StarLight Optical Switching projects.

We calculated linear and nonlinear responses of a Kerr nonlinear microsphere sandwiched by two prisms using the excitation of whispering gallery modes due to near-field coupling. As numerical calculations, the finite-difference time-domain method that takes into account the Kerr nonlinear effect was used. We dealt with two types of spheres, i.e., the Kerr-material sphere and the dielectric sphere coated by the Kerr material. It was found that the optical switching phenomena are induced in such spheres. The switching results from the fact that the variations of the refractive index of the nonlinear spheres affect the excitation condition of the whispering gallery modes.

Recent activities on ultrafast photonic device technology development in the Femtosecond Technology Project sponsored by NEDO are introduced. Topics include management and control of the higher order dispersions of optical fibers, ultrafast mode-locked semiconductor laser, symmetric Mach-Zehnder type all-optical switch, ultrafast serial-to-parallel signal converter and sub-picosecond wavelength switch. Challenges towards novel ultrafast switching material systems are also described.

We demonstrate all-optical clock recovery at 160 Gbit/s by injection locking of a 10 GHz mode-locked laser diode. Effective locking in a range of 10 MHz is observed for average input powers around -10 dBm. The timing jitter is analyzed for data rates between 10 Gbit/s and 160 Gbit/s. Beyond 40 Gbit/s, the high frequency timing jitter of the slave laser becomes of prime importance and has to be taken into account since it degrades the performance of a subsequent receiver. Increasing power penalties are found, especially beyond 80 Gbit/s.

A photon-induced waveguide (PIG) for all-optical switching and wavelength conversion with the functionalities of regeneration and reshaping is proposed. Optical signals are used to switch between lateral optical wave guiding and antiguiding effects. A transfer-matrix method was developed to consider not only the variation of optical signal power along the waveguide, but also the spatial distributions of refractive index and optical confinement factor to explain the switching scheme between guiding and antiguiding. Theoretical analyses show that a threshold-like and sharp input-output response of PIG allows enhancement of the extinction ratio, reshaping, and thus enlargement of noise margin of optical signals in digital all-optical switching and wavelength conversion.

We present three-wave mixing devices useful for signal processing functions in WDM and TDM systems, including wavelength conversion, spectral inversion, and gated mixing. These mixers exhibit extremely wide bandwidth, low noise, high efficiency, and format transparency.