This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer

Optical Packet and Burst Switching Technologies for the Future Photonic Internet

Fiber Bragg gratings (FBGs) have emerged as important components in a variety of lightwave applications. Their unique filtering properties and versatility as in-fiber devices is illustrated by their use in wavelength-stabilized lasers, fiber lasers, remotely pump amplifiers. Raman amplifiers, phase conjugators, wavelength converters, passive optical networks, wavelength division multiplexers (WDMs) demultiplexers, add/drop multiplexers, dispersion compensators, and gain equalizers.

Lightwave applications of fiber Bragg gratings

A hierarchical network management system (NMS) in which a plurality of NMS managers, each responsible for different portions or aggregations of a communications network, are logically arranged in a tree structure. The NMS managers are further organized into various sub-groups. The NMS managers within each sub-group monitor the status of one another in order to detect when one of them is no longer operational. If this happens, the remaining operational NMS managers of the sub-group collectively elect one of them to assume the responsibility of the non-operational NMS manager. The NMS is thus “self-healing” in the sense that one NMS manager can dynamically, without operator intervention, assume the responsibilities for another NMS manager.

Self-healing hierarchical network management system, and methods and apparatus therefor

A single-mode fiber connectorized microelectromechanical systems (MEMS) reflective optical switch attenuator operating in the 1550-nm wavelength region is described The device consists of an electrostatically actuated gold-coated silicon vane interposed in a fiber gap yielding 081-dB minimum insertion loss in the transmit state and high transmission isolation in the reflection state with 215-dB minimum return loss The switch attenuators also work as continuously variable optical attenuators capable of greater than 50-dB dynamic range and can be accurately regulated with a simple feedback control circuit Switching voltages were in the range of 5-40 V and a switching time of 64 /spl mu/s was achieved The MEMS switch can be used in optical subsystems within a wavelength-division-multiplexed (WDM) optical network such as optical power regulators, crossconnects, and add/drop multiplexers We used a discrete array of 16 switch attenuators to implement a reconfigurable 16-channel 100-GHz spacing WDM drop module of an add/drop multiplexer Thru-channel extinction was greater than 40 dB and average insertion loss was 21 dB Both drop-and-transmit of multiple channels (11-18-dB contrast, 14-19-dB insertion loss) and drop-and-detect of single channels (>20-dB adjacent channel rejection, 10-14-dB insertion loss) were demonstrated

A silicon MEMS optical switch attenuator and its use in lightwave subsystems

High-end access networks that serve large businesses and campuses will greatly benefit from the introduction of WDM technology, in terms of greater bandwidth, increased flexibility, and enhanced services. We refer to such networks as optical regional and metropolitan access networks (ORMA-Nets). Here, we qualitatively and quantitatively investigate many important principles, as well as challenges, in deploying ORMA-Nets. Access networks in general are functionally comprised of a feeder network, which is responsible for traffic aggregation, and a distribution network, which directly interfaces with the customer premises. We present several configurable, scalable designs for the feeder network that are capable of aggregating a range of traffic types and rates. We also present architectures for achieving a high degree of functionality using relatively low-cost, passive optical components in the distribution network. We explore topics such as optimal switch placement and wavelength banding, and emphasize the technologies that are needed to deliver advanced capabilities. Various underlying themes run throughout the paper, such as optionally not always using bandwidth as efficiently as possible in order to simplify the architecture, and the importance of transparency in providing enhanced services and architectural flexibility.

Architectural principles of optical regional and metropolitan access networks

We present a new optics-based transport architecture that emulates fast switching in the network core via emerging fast tunable lasers at the network edge, and bypasses the need for fast optical switching and buffering. The new architecture is capable of handling both asynchronous and synchronous traffic, for dealing with various bandwidth granularities and responding to dynamic changes in end-to-end traffic demands. The architecture also reduces the amount of layering in the transport network by eliminating packet and TDM switching, keeps the network core light (lightweight and transparent), and pushes intelligence to the network edge. We discuss technical challenges that arise in the new architecture and describe possible approaches to address them.

Light core and intelligent edge for a flexible, thin-layered, and cost-effective optical transport network

A micro-opto-electromechanical systems (MOEMS) device comprises a micro-electromechanical systems (MEMS) device and a silicon optical-bench (SiOB) device or system. The MEMS device interacts with the SiOB mechanically or electromagnetically. In one embodiment, the MEMS device is operable to provide a switching function for the SiOB device. The MEMS device comprises an actuator that is mechanically linked to an optical interruptor that prevents at least a portion of an optical signal incident thereon from propagating therethrough. In an actuated state, the actuator causes the optical interrupter to move into an optical path of an optical signal traveling through an SiOB device. The signal is at least partially reflected or absorbed such that only a portion of the signal propagates beyond the point of contact with the optical interrupter. Since SiOB processing is typically incompatible with MEMS device processing, the MEMS and SiOB devices are formed on separate supports and then attached, such as via flip-chip bonding methods.

Micro-opto-electromechanical devices and method therefor

It is found experimentally that the differential phase-shift-keyed (DPSK) signal with balanced detection has /spl sim/6 dB higher tolerance to in-band coherent crosstalk than on-off-keyed (OOK) signal. We attribute the improved crosstalk tolerance of the DPSK signal to its 6-dB lowered peak signal power as compared to the OOK signal for equal bit-error rate in optical signal-to-noise-ratio-limited systems. The impact of signal coherence on the crosstalk tolerance in a 10-Gb/s DPSK system adopting a standard Reed-Solomon forward-error correction is also investigated.

Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC

Signal losses in an optical cross-connect having steerable switching elements for routing optical signals are substantially reduced by controllably and selectively training the steerable switching elements as a function of measured input and output power of a cross-connected optical signal. More specifically, adjustments to the alignment of one or more steerable switching elements associated with a particular cross-connection are performed in a non-intrusive manner to increase the optical signal power in an optical signal while maintaining an active cross-connection of the optical signal. In one illustrative embodiment, optical monitoring arrangements monitor the optical signal power of optical signals coupled to the cross-connect inputs and outputs. The cross-connect includes a switching fabric comprising a plurality of steerable MEMS mirror elements used as switching elements for controllably and selectively directing the light beams within the cross-connect. By comparing the measured optical signal power with a previously stored value representing the expected optical signal power for that cross-connection, small adjustments can then be made, as appropriate, to optimize the alignment of the mirrors associated with the cross-connection. For example, if the difference between the measured and expected optical signal power exceeds a prescribed threshold, then a dithering process is initiated whereby individual mirrors are “walked through” alternate tilt positions until the measured optical signal power has been optimized, e.g., increased.

System and method for training an optical cross-connect comprising steerable switching elements

A communication system adapted to use wavelength (frequency) division multiplexing for quantum-key distribution (QKD). In one embodiment, a communication system of the invention has a transmitter coupled to a receiver via a transmission link. The transmitter has (i) a first optical-frequency comb source (OFCS) adapted to generate a first plurality of uniformly spaced frequency components and (ii) a first multi-channel optical modulator adapted to independently modulate each component of the first plurality to produce a quantum-information (QI) signal applied to the transmission link. The receiver has (i) a second OFCS adapted to generate a second plurality of uniformly spaced frequency components and (ii) a second multi-channel optical modulator adapted to independently modulate each component of the second plurality to produce a local- oscillator (LO) signal. Each of the first and second optical-frequency comb sources is referenced to a frequency standard such that the frequency components generated by these comb sources have substantially the same frequencies. The receiver employs a multi channel homodyne detector adapted to process interference signals produced by combining the LO signal with the QI signal to ascertain quantum information carried by the QI signal.

Randy Clinton Giles

Papers

Light core and intelligent edge for a flexible, thin-layered, and cost-effective optical transport network

Micro-opto-electromechanical devices and method therefor

Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC

System and method for training an optical cross-connect comprising steerable switching elements

Multi-channel transmission of quantum information