D. C. Kilper

Energy Efficient Networks

Networks are key part of overall social strategy to reduce carbon footprint ▪ Essential tool in realizing sustainable living ▪ Must be reconciled with network growth Scaling networks is becoming harder Understanding energy use in networks is a complex and important problem ▪ Access to data will be an on-going challenge ▪ Complimentary methods available: network model vs. energy accounting Much recent activity looking at core network techniques ▪ EE-network design and traffic engineering ▪ Dynamic wavelength capabilities Need to look beyond current network paradigm to address long term challenges

Transient gain dynamics of cascaded erbium doped fiber amplifiers with re-configured channel loading

Wavelength-division-multiplexed channel power transients are examined in cascaded EDFAs with variable pre-transient channel loading through the chain. We identify different orders of transient events and characterize their uncontrolled time response and steady-state power excursions.

Ultra-sensitive optical sampling by coherent-linear detection

Optical sampling is achieved using an all-optical linear technique with a record sensitivity of 10/sup -3/ mW/sup 2/, 1000 times better than nonlinear techniques. Phase sensitivity is removed by simultaneous measurement of orthogonal phase quadratures.

Cost Study of Dynamically Transparent Networks

The network equipment cost benefit of dynamic wavelength routing is compared with point-to-point IP networks and static wavelength routing in a simple ring topology with variable network traffic loading.

Fundamental limits on energy use in optical networks

Fundamental energy limits in communication systems are reviewed and applied to a gedanken network model in order to determine the corresponding ideal minimum energy requirements on classical, non-adiabatic, uniform-demand optical networks.

Channel Power Coupling in Constant Gain Controlled Amplifiers

Channel power coupling due to gain ripple and tilt in constant gain controlled erbium doped fiber amplifiers is measured in a transmission line and shown to grow in cascade.

Impact of wavelength route correlation on the optimal placement of optical monitors in transparent mesh networks

Wavelength route correlation is considered for optimal monitor placement in transparent networks. The associated reduction in monitoring requirement is studied as a function of repair cost and traffic loading.

Impact of topology and traffic on physical layer monitoring in transparent networks

The benefit of optical performance monitoring, in terms of addressing the extent of optical transparency, is analyzed with respect to network topology and traffic patterns.

Wavelength-dependent channel power transient response in broadband Raman-amplified transmission

The time evolution of uncontrolled amplifier gain transients due to dropped or cut dense-wavelength-division multiplexed channels in a broadband all-Raman amplified recirculating loop experiment is measured for different surviving channel wavelength configurations with propagation up to 7200 km. Different time signatures develop depending on whether the surviving channels are located at the long- or short-wavelength end of the spectrum. Channel power tilt and gain error within a surviving channel group can vary with distance and are shown to correlate with growth of amplified spontaneous emission noise at the dropped channel wavelengths.

Testbed methods to study physical layer path establishment in long haul optical wavelength switched networks

To cope with increasing traffic, optical networks have steadily adopted faster interfaces. Interfaces working at 40 Gb/s were recently introduced in networks already deployed at 10 Gb/s; moreover, 100 Gb/s interfaces have been demonstrated in laboratory experiments [1]. As this upgrade in bit-rate tends to evolve over time scales faster than the lifetime of deployed systems, wavelength division multiplexed (WDM) systems may be required to support simultaneous transmission of signals modulated at different rates. These signals can have very different transmission properties and optimal designs often employ unique modulation formats for each bit rate. For example, non return to zero on-off keyed modulation is commonly used at 10 Gb/s, whereas phase-shift-keyed modulation formats, such as differential phase shift keying, are used at 40 Gb/s. More complex modulation formats are proposed at 100 Gb/s and recent studies consider the use of orthogonal frequency division multiplexing to make the channel capacity flexible, ranging from 10 up to 100 Gb/s and higher [2]. This wide variation in modulation technologies motivates the use of a network infrastructure that supports transmission heterogeneity without costly changes when a new bit rate or format is introduced. Transparent networks have the advantage of providing a flexible infrastructure with the potential to enable the introduction of new modulation technologies by changing only the extremity interfaces. Optical transparency is possible thanks to the introduction of optical switches, such as wavelength selective switches (WSS), avoiding systematic optoelectronic conversion at nodes, and also thanks to improvements in transmission performance, enabling reaches of several thousand kilometers and many nodes before needing optoelectronic regeneration.