Packet-optical Add/Drop multiplexer technology: A pragmatic way to introduce optical packet switching in the next generation of metro networks
This paper describes a packet-optical add/drop multiplexer technology designed for Metro-ring networks to reduce cost and power consumption with a network efficiency comparable to a full-electronic Ethernet solution. A demonstrator including three nodes is shown.
Wavelength locking a fast-switching tunable laser
We demonstrate wavelength locking in a widely tunable fast-switching laser module that accesses 64 ITU channels with 50-GHz spacing and switches wavelength in under 50 ns. We use a Fabry-Pe/spl acute/rot etalon to stabilize the laser frequency against long-term drifts. We demonstrate locking while continuously switching with random channel schedules of 1-/spl mu/s packets. The locked frequency accuracy of /spl plusmn/3 GHz is a factor of two improvement over operation without locking. We also present the dynamics of the frequency drift due to temperature variation in the laser, and show the correlation between the frequency offsets while locking and the electrical power dissipated in the tuning sections.
Two-dimensional gravitational anomalies, Schwinger terms and dispersion relations
Abstract We are dealing with two-dimensional gravitational anomalies, specifically with the Einstein anomaly and the Weyl anomaly, and we show that they are fully determined by dispersion relations independent of any renormalization procedure (or ultraviolet regularization). The origin of the anomalies is the existence of a superconvergence sum rule for the imaginary part of the relevant formfactor. In the zero mass limit the imaginary part of the formfactor approaches a δ-function singularity at zero momentum squared, exhibiting in this way the infrared feature of the gravitational anomalies. We find an equivalence between the dispersive approach and the dimensional regularization procedure. The Schwinger terms appearing in the equal time commutators of the energy momentum tensors can be calculated by the same dispersive method. Although all computations are performed in two dimensions the method is expected to work in higher dimensions too.