116 research outputs found
Differentiated ABR: A new architecture for flow control and service differentiation in optical burst switched networks
In this paper, we study a new control plane protocol, called Differentiated ABR (D-ABR), for flow control and service differentiation in optical burst switched networks. Using D-ABR, we show using simulations that the optical network can be designed to work at any desired burst blocking probability by the flow control service of the proposed architecture. This architecture requires certain modifications to the existing control plane mechanisms as well as incorporation of certain scheduling mechanisms at the ingress nodes; however we do not make any specific assumptions on the data plane for the optical core nodes. Moreover, with this protocol, it is possible to almost perfectly isolate high priority and low priority traffic throughout the optical network as in the strict priority-based service differentiation in electronically switched networks. © 2005 IEEE
Terahertz All-Optical Modulation in a Silicon-Polymer Hybrid System
Although Gigahertz-scale free-carrier modulators have been previously
demonstrated in silicon, intensity modulators operating at Terahertz speeds
have not been reported because of silicon's weak ultrafast optical
nonlinearity. We have demonstrated intensity modulation of light with light in
a silicon-polymer integrated waveguide device, based on the all-optical Kerr
effect - the same ultrafast effect used in four-wave mixing. Direct
measurements of time-domain intensity modulation are made at speeds of 10 GHz.
We showed experimentally that the ultrafast mechanism of this modulation
functions at the optical frequency through spectral measurements, and that
intensity modulation at frequencies in excess of 1 THz can be obtained in this
device. By integrating optical polymers through evanescent coupling to
high-mode-confinement silicon waveguides, we greatly increase the effective
nonlinearity of the waveguide for cross-phase modulation. The combination of
high mode confinement, multiple integrated optical components, and high
nonlinearities produces all-optical ultrafast devices operating at
continuous-wave power levels compatible with telecommunication systems.
Although far from commercial radio frequency optical modulator standards in
terms of extinction, these devices are a first step in development of
large-scale integrated ultrafast optical logic in silicon, and are two orders
of magnitude faster than previously reported silicon devices.Comment: Under consideration at Nature Material
Hybrid integration of III/V lasers on a silicon-on-insulator (SOI) optical board
Abstract: Heterogeneous integration of III-V semiconductor materials on a silicon-on-insulator (SOI) platform has recently emerged as one of the most promising methods for the fabrication of active photonic devices in silicon photonics. For this integration, it is essential to have a reliable and robust bonding procedure, which also provides a uniform and ultra-thin bonding layer for an effective optical coupling between III-V active layers and SOI waveguides. A new process for bonding of III-V dies to processed siliconon-insulator waveguide circuits using divinylsiloxane-bis-benzocyclobutene (DVS-BCB) was developed using a commercial wafer bonder. This "cold bonding" method significantly simplifies the bonding preparation for machine-based bonding both for die and wafer-scale bonding. High-quality bonding, with ultra-thin bonding layers (<50 nm) is demonstrated, which is suitable for the fabrication of heterogeneously integrated photonic devices, specifically hybrid III-V/Si lasers. K. Mayora, "Novel three-dimensional embedded SU-8 microchannels fabricated using a low temperature full wafer adhesive bonding," J. Micromech. Microeng. 14(7), 1047-1056 (200
Rate-controlled optical burst switching for both congestion avoidance and service differentiation
Cataloged from PDF version of article.Optical Burst Switching (OBS) has recently been proposed as a candidate architecture for the next generation optical Internet.
Several challenging issues remain to be solved to pave the way for the OBS vision. Contention arises in OBS networks when two
or more bursts are destined for the same wavelength, and a wide variety of reactive contention resolution mechanisms have been
proposed in the literature. One challenging issue in OBS is proactively controlling the traffic flowing through the OBS network
so that the network does not stay in a persistent state of contention, which we call the congestion avoidance problem. Another
challenging issue is the need for service differentiation, which is common today in electronically switched networks via the use
of advanced buffer management and scheduling mechanisms. However, such mechanisms cannot be used in OBS networks due to
the limited use, or total absence, of buffering. One of the popular existing approaches to service differentiation in OBS networks
is the use of larger offset times for high-priority bursts which, however, increases the delays and may adversely affect applicationlevel
performance. In this paper, we propose a feedback-based rate control protocol for the control plane of the OBS network to
both address the congestion avoidance and service differentiation issues. Using this protocol, the incoming traffic is dynamically
shaped at the edge of the OBS network in order to avoid potential congestion in the burst-switched core. Moreover, the traffic
shaping policies for the low and high priority traffic classes are different, and it is possible using the proposed protocol to isolate
high-priority and low-priority traffic almost perfectly over time scales on the order of a few round-trip times. Simulation results are
reported to validate the congestion avoidance and service differentiation capabilities of the proposed architecture.
(C) 2006 Elsevier B.V. All rights reserved
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