J. Gripp

Optical switch fabrics for ultra-high-capacity IP routers

Next-generation switches and routers may rely on optical switch fabrics to overcome scalability problems that arise in sizing traditional electrical backplanes into the terabit regime. In this paper, we present and discuss several optical switch fabric technologies. We describe a promising approach based on arrayed waveguide gratings and fast wavelength tuning and explain the challenges with respect to technical and commercial viability. Finally, we demonstrate an optical switch fabric capable of 1.2-Tb/s throughput and show packet switching with four ports running at 40 Gb/s each.

Demonstration of the interconnection of two optical packet rings with a hybrid optoelectronic packet router

We demonstrate the interconnection of two optical packet switching systems: a hybrid optoelectronic packet router and two optical packet rings. Error-free inter-ring and intra-ring optical packet transmission and unicast and multicast transport of encapsulated 10 GbE are achieved.

Fast switching characteristics of a widely tunable laser transmitter

We demonstrate a widely tunable laser transmitter that accesses 32 ITU channels with 100-GHz spacing and switches between all channel combinations in less than 45 ns. The compact module uses commercially available electronic components. We investigate the electrical and thermal properties of the laser and the tuning section driver. The experiments show that a low output impedance driver circuit produces faster switching times. Also, temperature variation of the laser limits the wavelength accuracy of the switching. Finally, we present the correlation between switching times and the laser tuning currents.

Fast-tuning 224-Gb/s intradyne receiver for optical packet networks

We demonstrate a digital coherent 224-Gb/s (56-Gbaud PDM-QPSK) packet receiver that selects packets using a fast wavelength-switching local oscillator. A novel three-stage CMA enables blind packet recovery in less than 200 ns.

Demonstration of a 1.2 Tb/s optical packet switch fabric (32/spl times/40 Gb/s) based on 40 Gb/s burst-mode clock-data-recovery, fast tunable lasers, and a high-performance N/spl times/N AWG

We demonstrate a 1.2 Tb/s optical packet switch fabric based on burst-mode clock-data-recovery at 40 Gb/s with packet separations of up to 400 ns and lock times under 5 ns fast wavelength switching between 32 channels in less than 46 ns and a 42/spl times/42 AWG (array waveguide grating) with a worst-case loss of 4.2 dB.

IRIS optical packet router [Invited]

Feature Issue on ConvergenceWe present a load-balanced packet router with an all-optical data plane and a decentralized control plane. The router, whose architecture scales up to 256 Tbit/s with current technology, consists of two space switches based on wavelength converters and large N×N arrayed-waveguide gratings, surrounding a deterministic time buffer. First experimental results have been obtained in a 2×2 testbed with 40 Gbit/s wavelength converters that use monolithically-integrated semiconductor optical amplifiers, and with fiber-delay-line time buffers.

Demonstration of an Integrated Buffer for an All-Optical Packet Router

An integrated silica 10-channel, AWG-based delay-line optical buffer with up to 100 ns delay is demonstrated. Error-free operation at 40 Gb/s is shown for all channels with penalties of ∼2–4 dB at BER = 10⁻⁹.

Fast packet routing in a 2.5 Tb/s optical switch fabric with 40 Gb/s duobinary signals at 0.8 b/s/Hz spectral efficiency

We demonstrate error-free 40 Gb/s duobinary packet routing by fast wavelength switching on two ports in a 64/spl times/64 passive optical switch fabric. Switching in less than 45 ns for all channel combinations and burst-mode clock recovery in less than 15 ns are achieved.

Architectures, Components, and Subsystems for Future Optical Packet Switches

Rapidly increasing network traffic is posing a challenge to the construction of future routers. While high-capacity transport has kept pace with rising traffic demands through the use of dense wavelength-division multiplexing, the scaling of core routers is slowed by power density limits and complexity and interconnectivity issues. Optical switching has the potential to overcome these scaling restrictions, and as a result, has generated great scientific and commercial interest. In this paper, we present an overview of some optical packet-switching architectures and describe components and subsystems that are required to enable this technology.

Architecture of an integrated router interconnected spectrally (IRIS)

The design of optical packet routers poses significant challenges both in terms of its architecture and component design. In this paper, we evaluate several alternatives for the architecture of such routers, and describe the architecture of IRIS (integrated router interconnected spectrally), an optical router being designed at Bell Laboratories. By combining load balancing with wavelength switching, the IRIS architecture can make use of thousands of wavelengths and provide terabits of capacity, well above the scalability limits of router architectures based on other approaches. The IRIS architecture uses load balancing to eliminate the need for centralized scheduling, and wavelength switching to allow N2 channels in an NtimesN space switch. We describe several architectural schemes for overcoming the limitations of the underlying optical devices in the design of IRIS. We also present two methods to improve the utilization of the optical buffers in IRIS to achieve high performance even with a small number of buffers