All-optical label swapping is a promising approach to ultra-high packet-rate routing and forwarding directly in the optical layer. In this paper, we review results of the DARPA Next Generation Internet program in all-optical label swapping at University of California at Santa Barbara (UCSB). We describe the overall network approach to encapsulate packets with optical labels and process forwarding and routing functions independent of packer bit rate and format. Various approaches to label coding using serial and subcarrier multiplexing addressing and the associated techniques for label erasure and rewriting, packet regeneration and packet-rate wavelength conversion are reviewed. These functions have been implemented using both fiber and semiconductor-based technologies and the ongoing effort at UCSB to integrate these functions is reported. We described experimental results for various components and label swapping functions and demonstration of 40 Gb/s optical label swapping. The advantages and disadvantages of using the various coding techniques and implementation technologies are discussed.

All-optical label swapping networks and technologies

Focus Serial: Frontiers of Nonlinear Optics Chalcogenide glasses offer large ultrafast third-order nonlinearities, low two-photon absorption and the absence of free carrier absorption in a photosensitive medium. This unique combination of properties is nearly ideal for all-optical signal processing devices. In this paper we review the key properties of these materials, outline progress in the field and focus on several recent highlights: high quality gratings, signal regeneration, pulse compression and wavelength conversion.

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Ultrafast all-optical chalcogenide glass photonic circuits

A system based on a highly nonlinear planar chalcogenide waveguide is demonstrated to be able to perform radio-frequency spectral measurements with a terahertz bandwidth. High bit-rate tests show that the chip-based system is potentially useful for ultrafast signal processing.

Photonic-chip-based radio-frequency spectrum analyser with terahertz bandwidth

Multiprotocol label switching (MPLS) is rapidly emerging as an Internet Engineering Task Force (IETF) standard intended to enhance the speed, scalability, and service provisioning capabilities in the Internet. MPLS uses the technique of packet forwarding based on labels, to enable the implementation of a simpler high-performance packet forwarding engine. This also decouples packet forwarding from routing, facilitating the provision of varied routing services independent of the packet forwarding paradigm. The authors track the evolution of this technology in relation to other existing technologies. Then an overview of the MPLS architecture and design is provided. In addition, some of the work that was a precursor to MPLS is discussed, as well as related issues and debates.

Evolution of multiprotocol label switching

A detailed description of the design guidelines for a full encoder/decoder that is able to generate/process a set of optical codes simultaneously is reported. The device has an array-waveguide-grating configuration, but the corresponding design rules are different from those of a multiplexer/demultiplexer. In an accurate model, based on diffraction theory, the slab diffraction effect and the loss nonuniformity are analyzed. Furthermore, the performance of the phase-shift-keyed codes simultaneously generated by the device and the corresponding packet-loss probability are also investigated.

Characterization of a full encoder/decoder in the AWG configuration for code-based photonic routers-part I: modeling and design

40-Gb/s return-to-zero data wavelength conversion is demonstrated using cross-phase modulation in an optical fiber with subsequent conversion of phase modulation to amplitude modulation using an optical filter. The scheme is potentially ultrahigh speed and can be made polarization independent.

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A simple and robust 40-Gb/s wavelength converter using fiber cross-phase modulation and optical filtering

40 Gbit/s packet wavelength routing and 2.5 Gbit/s header replacement is demonstrated using an ultra-high-speed wavelength converter. Burst-mode bit error rate measurements are performed on both the header and payload before and after wavelength routing, with <4 dB penalty in the payload and <2.5 dB penalty in the header.

Wavelength routing of 40 Gbit/s packets with 2.5 Gbit/s header erasure/rewriting using all-fibre wavelength converter

A 40-Gb/s wavelength converter based on cross-phase modulation in a dispersion-shifted fiber has been investigated through pulse measurements and simulation. The most important parameter is the dispersive walkoff, which makes the required input power wavelength dependent and determines the optical bandwidth. Simulations show the feasibility of the 160-Gb/s operation by using 2-ps pulses and a highly nonlinear dispersion-shifted fiber.

Wavelength dependence and power requirements of a wavelength converter based on XPM in a dispersion-shifted optical fiber

All-optical erasure and rewriting of 2.5-Gb/s nonreturn-to-zero (NRZ) data from high-speed return-to-zero (RZ) data has been demonstrated using a fiber-based wavelength converter. Such a wavelength converter will block the low frequencies of the NRZ data while converting the RZ pulses. This approach uses the frequency discriminating feature of the wavelength converter, and does not require active control. Penalty-free rewriting of new NRZ data was then performed.

All-optical header erasure and penalty-free rewriting in a fiber-based high-speed wavelength converter

40 Gbit/s RZ data wavelength conversion is demonstrated using cross-phase modulation in an optical fiber with subsequent conversion of phase modulation to amplitude modulation using an optical filter. The scheme is potentially ultra high speed and can be made polarization independent.

P. Ohlen

Papers

A simple and robust 40-Gb/s wavelength converter using fiber cross-phase modulation and optical filtering

Wavelength routing of 40 Gbit/s packets with 2.5 Gbit/s header erasure/rewriting using all-fibre wavelength converter

Wavelength dependence and power requirements of a wavelength converter based on XPM in a dispersion-shifted optical fiber

All-optical header erasure and penalty-free rewriting in a fiber-based high-speed wavelength converter

A simple and robust high-speed wavelength converter using fiber cross-phase modulation and filtering