Lavanya Rau

All-optical label swapping networks and technologies

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.

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

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.

All-optical label swapping with wavelength conversion for WDM-IP networks with subcarrier multiplexed addressing

We report the first demonstration of all-optical label swapping with wavelength conversion and subcarrier multiplexed addressing for WDR IP. This demonstration utilizes a module which is based on cascaded semiconductor optical amplifier wavelength converters that perform the functions of label removal, label rewriting, payload 2R regeneration and double sideband subcarrier label regeneration. Replacement of double-sideband subcarrier labels on a hop-by-hop basis addresses the problem of dispersion induced fading in a multihop fiber network. A direct detection subcarrier receiver is used to recover the label. Switching over four wavelengths covering 16 nn is demonstrated with noninverting wavelength conversion of 2.5-Gb/s payloads and burst mode recovery of 10-Mb/s labels. BER measurements of better than 10/sup -9/ for the wavelength-converted payload and rewritten labels at all wavelengths are presented.

Widely tunable monolithically integrated all-optical wavelength converters in InP

Design, fabrication, and characterization of monolithically integrated widely tunable all-optical wavelength converters in InP is reported. The devices are based on the SGDBR laser integrated with different MZI-SOA wavelength converters. Error-free wavelength conversion at 2.5 Gbps was demonstrated over 50 nm input and 22 nm output wavelength range. Static operation, extinction ratio enhancement, signal reamplification, dynamic range, and chirp properties were characterized as well.

Raman-enhanced regenerative ultrafast all-optical fiber XPM wavelength converter

The Raman gain enhancement of a regenerative ultrafast all-optical cross-phase modulation (XPM) wavelength converter (WC) is quantitatively investigated and experimentally demonstrated to operate error free at 40 and 80 Gb/s. The regenerative nature of the converter is shown by experimentally demonstrating a negative 2-dB power penalty at 80 Gb/s. It is also shown that the Raman gain greatly enhances the wavelength conversion efficiency at 80 Gb/s by 21 dB at a Raman pump power of 600 mW using 1 km of highly nonlinear fiber. An analytical theory based on nonlinear phase-shift enhancement of the fiber-effective length is presented and shows the relationship between a nonlinear enhancement and Raman gain as a function of pump power and fiber design parameters. Measured parameters are used in the analytical model, and a good fit between experiment and theory is shown for two different types of fiber: one dispersion-shifted and one highly nonlinear fiber. The ultrafast response time of Raman gain makes this technique applicable to fiber-based ultrafast WCs. In addition, the applicability to other nonlinear fiber wavelength conversion techniques is discussed.

160 Gb/s variable length packet/10 Gb/s-label all-optical label switching with wavelength conversion and unicast/multicast operation

We report on the first demonstration of all-optical label switching (AOLS) with 160 Gb/s variable length packets and 10 Gb/s optical labels. This result demonstrates the transparency of AOLS techniques from previously demonstrated 2.5 Gb/s to this 160 Gb/s demonstration using a common routing and packet lookup framework. Packet forwarding/conversion, optical label erasure/re-write and signal regeneration at 160 Gb/s is achieved using a WDM Raman enhanced all-optical fiber cross-phase modulation wavelength converter. It is also experimentally shown that this technique enables packet unicast and multicast operation at 160 Gb/s. The packet bit-error-rate is measured for all optical label switched 16 /spl times/ 10 Gb/s channels and error free operation is demonstrated after both label swapping and packet forwarding.

All-optical contention resolution with wavelength conversion for asynchronous variable-length 40 Gb/s optical packets

We present a new all-optical technique for resolving contention between asynchronous variable length packets. The approach utilizes a novel all-optical asynchronous latching switch based on cross-coupled injection-locked wavelength converters. We experimentally demonstrate that the scheme resolves contention between variable-length, asynchronous 40 Gb/s packets with a measured bit error rate of better than 10/sup -9/, without an error floor.

WDM optical IP tag switching with packet-rate wavelength conversion and subcarrier multiplexed addressing

We believe we have demonstrated for the first time wavelength-division multiplexing (WDM) all-optical IP tag switching with wavelength conversion and subcarrier multiplexed addressing. Switching over four wavelengths covering 16 nm was demonstrated with noninverting wavelength conversion of 2.5 Gbps payloads and burst mode recovery of tag/headers.

All-optical 160-Gb/s phase reconstructing wavelength conversion using cross-phase modulation (XPM) in dispersion-shifted fiber

Wavelength conversion using cross-phase modulation in dispersion-shifted fiber at 160 Gb/s is demonstrated. It is shown for the first time that the converter reconstructs the phase of the input signal, an important property for transmission of 160-Gb/s data. The bit-error rate of the converted channels is measured to be better than 10/sup -9/ with a power penalty of <3 dB and in some cases negative compared to the original unconverted optical time-division-multiplexing signal across all 16/spl times/10-Gb/s channels.

Two-hop all-optical label swapping with variable length 80 Gb/s packets and 10 Gb/s labels using nonlinear fiber wavelength converters, unicast/multicast output and a single EAM for 80- to 10 Gb/s packet demultiplexing

We demonstrate for the first time two hops of all-optical label swapping of variable length 80 Gb/s packets and 10 Gb/s optical labels, with unicast/multicast capability using an all-optical fiber cross-phase modulation wavelength converter.