Photonic packet switches: architectures and experimentalimplementations

Photonic packet switches offer high speed, data rate and format transparency, and flexibility required by future computer communications and cell-based telecommunications networks. In this paper, we review experimental progress in state-of-the-art photonic packet switches with an emphasis on all-optical guided-wave systems. The term all-optical implies that the data portion of a packet remains in optical format from the source to the destination. While the data remain all-optical, both optical and optoelectronic techniques have been used to process packet routing functions based on extremely simple routing protocols. An overview of the design issues for all-optical photonic packet switching is given and contrasted with electronic packet switch implementations. Low-level functions that have been experimentally implemented include routing, contention resolution, synchronization, and header regeneration. System level demonstrations, including centralized photonic switching and distributed all-optical multihop networks, will be reviewed     

Comparison of Sagnac and Mach-Zehnder ultrafast all-optical interferometric switches based on a semiconductor resonant optical nonlinearity

We present a theoretical analysis of recently demonstrated ultrafast all-optical interferometric switching devices (based on Sagnac and Mach-Zehnder interferometers) that use a large optical nonlinearity in a resonant regime. These devices achieve ~10-ps switching windows and do not require high-energy optical control pulses. We theoretically analyze and compare one Sagnac and two Mach-Zehnder switching configurations.     

Self-clocked optical control of a self-routed photonic switch

Self-routing of 100-Mb/s data through a photonic switch is demonstrated. Individual data bits are subencoded into one of 124 destination addresses using a pulse-interval technique with 80-ps pulses. At the switch, optical processing is used to read the address of an incoming bit and to route that bit to the correct switch output without the aid of an external clock. Although the pulse-interval technique is presented in a bit-switching context, it can readily be extended to a packet-switching environment     

Performance of an 8×8 LiNbO3switch matrix as a gigahertz self-routing switching node

The performance of an LiNbO3 integrated-optic crossbar switch as a node in a gigahertz self-routing network is measured. Switch throughput supports 12.5 Gbit/s signals with a measured switching speed of 1.33 GHz. Crosstalk due to RF/ acousto-optic coupling and modulation depth are reported at 1.33 GHz. Optical self-routing of l00 Mbit/s information using the 8×8 switch is demonstrated.     

TDMA fibre-optic network with optical processing

A fibre-optic network with time-division multiple access (TDMA) is implemented using optical processing. The network is capable of accommodating 50 stations transmitting at 10Mbit/s. Synchronisation is achieved using a central optical source with 2ns pulses. Integrated electro-optic modulators and optical fibre delay lines are used to multiplex the stations.     

Demonstration of packet switching through an integrated-optic tree switch using photo-conductive logic gates

Optical routing control of 10 Gbit/s data through a tree-structured photonic switch is experimentally demonstrated. A binary route address within a header is optically processed to control the switch.<>     

Routing of 100 Gb/s words in a packet-switched optical networkingdemonstration (POND) node

This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength time division multiplexed (TDM) packet bit rates as high as 100 Gb/s. The physical topology of the packet-switched optical networking demonstration (POND) node is based on an eight-node ShuffleNet architecture. The key enabling technologies required to implement the node such as ultrafast packet generation, high-speed packet demultiplexing, and efficient packet routing schemes are described in detail. The routing approach taken is a hybrid implementation in which the packet data is maintained purely in the optical domain from source to destination whereas control information is read from the packet header at each node and converted to the electrical domain for an efficient means of implementing routing control. The technologies developed for the interconnection network presented in this paper can be applied to larger metropolitan and wide area networks as well     

Ultrafast All-Optical Synchronous Multiple Access Fiber Networks

Two synchronous multiple access schemes, TDMA and CDMA, are proposed for fiber optic networks using optical signal processing. Network synchronization is achieved by using a central modelocked laser which also serves as the source for each station. The data are converted into a high-bandwidth optical signal using electrooptic modulators. The accessing schemes use optical fiber delay lines. The feasibility of these schemes is discussed.     

The modified beam propagation method

A method is presented for the analysis of waveguide structures with abrupt index changes in both the transverse and axial directions. The method accurately includes the reflected fields and the Goos-Hanchen shift. The method can be extended to three-dimensional and graded index structures, and to include diffraction effects. For a graded index structure with no abrupt index changes the method reduces to the standard beam propagation method     

Analytical evaluation of improved access techniques in deflectionrouting networks

This paper presents an extension of a known analytical model for the performance evaluation of nonpriority deflection routing networks in uniform traffic. The extension allows the analysis of improved access techniques. The key features of the analytical technique are described by casting it in a very simple setting: nonpriority hot-potato in a two-connected slotted shufflenet (SN) network. Results are presented for three access techniques: transmit-no-hold (TXNH), transmit-hold (TXH), and bypass queuing (BQ)