Analysis of Large-Scale Multi-Stage All-Optical Packet Switching Routers

Research Paper (Abstract):
All-optical packet switching can overcome limitations of electronic switches in terms of power consumption, speed, cost, and footprint. Switch architectures combining wavelength converters and fiber delay lines provide tunable routing and contention resolution when used with an N×N arrayed waveguide grating (AWG), a key passive optical component to bypass electronic processing limitations. An AWG passively routes either single or multiple input port wavelengths to output ports. A single wavelength per port strategy reduces crosstalk within the AWG, but drastically increases the dimensionality of the device. AWG design constraints due to bandwidth limitations and fabrication processes limit the port number for the foreseeable future to under 100. In order to scale optical switches to emerging network requirements, we must use multiple wavelengths per port.

In this paper, the researchers examine several optical router architectures for data center applications using multiple wavelengths per port, and quantify the physical layer impairments. They consider not only the AWG crosstalk, but also Q-factor degradation caused by the multiple wavelength conversions occurring when a packet is buffered for contention resolution. They present the results as a function of the number of recirculations for on–off-keying (OOK) signal formats. While previous work has addressed this issue in terms of accumulated loss, the researchers focus on accumulated intensity noise due to crosstalk and amplified spontaneous emission (ASE). They compare the routing performance of each architecture, and they point out that the AWG crosstalk and accumulated ASE noise during packet recirculation are both critical to the routing performance.

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Q. Xu, H. Rastegarfar, Y. Ben M’Sallem, A. Leon-Garcia, S. LaRochelle, and L. A. Rusch

Journal of Optical Communications and Networking, Vol. 4, Issue 5, pp. 412-425 (2012)
http://dx.doi.org/10.1364/JOCN.4.000412

History
Original Manuscript: September 9, 2011
Revised Manuscript: February 2, 2012
Manuscript Accepted: April 9, 2012
Published: April 30, 2012


 Citation
Q. Xu, H. Rastegarfar, Y. Ben M’Sallem, A. Leon-Garcia, S. LaRochelle, and L. A. Rusch, "Analysis of Large-Scale Multi-Stage All-Optical Packet Switching Routers," J. Opt. Commun. Netw. 4, 412-425 (2012)
http://www.opticsinfobase.org/jocn/abstract.cfm?URI=jocn-4-5-412

Source:   Optical Society of America