S. J. Ben Yoo

All-optical packet-switched networks: a study of contention-resolution schemes in an irregular mesh network with variable-sized packets

This paper presents a comparative study of contention-resolution schemes based on wavelength, time, and space domains in an unslotted optical packet-switched network with a large irregular mesh topology consisted of 15 nodes. For the first time, to the best of our knowledge, we investigated the effect of selective deflection and limited wavelength conversion. Features and performances of different combinational schemes are listed and compared. While simulation results show the effectiveness of wavelength conversion for resolving contentions over optical buffering and space deflection, physical explanations of the different effectiveness in resolving contentions of these schemes are also discussed.

A comparison study between slotted and unslotted all-optical packet-switched network with priority-based routing

We present a comparison between a slotted and unslotted all-optical packet-switched network with priority-based routing. Packet loss rate below 0.01 with transmitter load less than 0.3 in the unslotted network is achieved by using buffering, limited wavelength conversion and deflection. OCIS codes: (060.4250) Networks.

High-fidelity line-by-line optical waveform generation and complete characterization using FROG

A stable optical frequency comb with 20-GHz spacing is shaped by a compact integrated silica arrayed waveguide grating (AWG) pair to produce optical waveforms with unprecedented fidelity. Complete characterization of both the intensity and phase of the crafted optical fields is accomplished with cross-correlation frequency resolved optical gating (XFROG) which has been optimized for periodic waveforms with resolvable modes. A new method is proposed to quantify, in a single number, the quality of the match in both the amplitude and phase between the measured optical waveform and the target waveform.

1705-km transmission over coupled-core fibre supporting 6 spatial modes

We present experimental transmission results for a novel 6-core coupled-core fibre with 125 μm cladding diameter. We transmit combined 2-polarization, 6-SDM and 30-WDM channels over a distance of 1705 km, with a spectral-efficiency-distance product of 30690 bit/s/Hz km.

High bandwidth on-chip silicon photonic interleaver

We demonstrate a 120 GHz 3-dB bandwidth on-chip silicon photonic interleaver with a flat passband over a broad spectral range of 70 nm. The structure of the interleaver is based on an asymmetric Mach-Zehnder interferometer (MZI) with 3 ring resonators coupled to the arms of the MZI. The transmission spectra of this device depict a rapid roll-off on the band edges, where the 20-dB bandwidth is measured to be 142 GHz. This device is optimized for operation in the C-band with a channel crosstalk as low as -20 dB. The device also has full reconfiguration capability to compensate for fabrication imperfections.

Continuously Tunable Optical Buffering at 40 Gb/s for Optical Packet Switching Networks

All-pass, wavelength-selective, slowlight optical buffers using cascaded micro-ring resonator filters are theoretically and experimentally studied in the context of optical packet switching router architectures. Two optical buffers fabricated in high-index contrast silica technology are compared: an 8-ring buffer with narrow resonances for wavelength selective delay and a 32-ring buffer for distortion-free delay at 10 and 40 Gb/s. Accurate measurements and configurations of the transmission of the buffers allow for precise simulations that accurately predict pattern dependent distortions, signal integrity and performance extrapolation to higher data rates. Continuously tunable delays are demonstrated up to 8 bits with minimal distortion.

A Scalable, Low-Latency, High-Throughput, Optical Interconnect Architecture Based on Arrayed Waveguide Grating Routers

This paper proposes, simulates, and experimentally demonstrates an optical interconnect architecture for large-scale computing systems. The proposed architecture, Hierarchical Lightwave Optical Interconnect Network (H-LION), leverages wavelength routing in arrayed waveguide grating routers (AWGRs), and computing nodes (or servers) with embedded routers and wavelength-specific optical I/Os. Within the racks and clusters, the interconnect topology is hierarchical all-to-all exploiting passive AWGRs. For the intercluster communication, the proposed architecture exploits a flat and distributed Thin-CLOS topology based on AWGR-based optical switches. H-LION can scale beyond 100 000 nodes while guaranteeing up to 1.83×saving in number of inter-rack cables, and up to 1.5×saving in number of inter-rack switches, when compared with a legacy three-tier Fat Tree network. Network simulation results show a system-wide network throughput reaching as high as 90% of the total possible capacity in case of synthetic traffic with uniform random distribution. Experiments show 97% intracluster throughput for uniform random traffic, and error-free intercluster communication at 10 Gb/s.

Multi-source multi-path video streaming over wireless mesh networks

This paper proposes to leverage multi-source multi-path diversity to design a video streaming system for supporting concurrent video-on-demand (VoD) services over wireless mesh networks (WMNs). By integrating a wireless interference model into consideration, we have a more realistic network model to capture the characteristics of wireless networks. Based on that, we mathematically formulate the route selection problem for the proposed streaming system using rate/interference-distortion optimization framework, and rely on a genetic algorithm to solve it heuristically. Simulation results show that the proposed system has better performance than systems using single-source, single-path and systems that do not consider interference

Scalable Optical Interconnect Architecture Using AWGR-Based TONAK LION Switch With Limited Number of Wavelengths

This paper analyzes the scalability in arrayed waveguide grating router (AWGR)-based interconnect architectures and demonstrates active AWGR-based switching using a distributed control plane. First, the paper analyses an all-to-all single AWGR passive interconnection with N nodes and proposes a new architecture that overcomes the scalability limitation given by wavelength registration and crosstalk, by introducing multiples of smaller AWGRs (W × W) operating on a fewer number of wavelengths . Second, this paper demonstrates active AWGR switching with a distributed control plane, to be used when the size of the interconnection network makes the all-to-all approach using passive AWGRs impractical. In particular, an active AWGR-based TONAK switch is introduced. TONAK combines an all-optical NACK technique, which removes the need for electrical buffers at the switch input/output ports, and a TOKEN technique, which enables a distributed all-optical arbiter to handle packet contention. The experimental validation and performance study of the AWGR-based TONAK switch is presented, demonstrating the feasibility of the TONAK solution and the high throughput and low average packet latency for an up to 75% offered load.

Optical FlowBroker: Load-Balancing in Software-Defined Multi-Domain Optical Networks

We present a new OpenFlow control architecture, referred to as Optical FlowBroker, for multi-domain software-defined optical networks. The hierarchical brokers improve scalability and inter-domain global coordination, while allowing domain controllers to manage intra-domain forwarding decisions.