Applied Constant Gain Amplification in Circulating Loop Experiments

Abstract

Abstract-The reconfiguration of channel or wavelength routes in optically transparent mesh networks can lead to deviations in channel power that may impact transmission performance. A new experimental approach, applied constant gain, is used to maintain constant gain in a circulating loop enabling the study of gain error effects on long-haul transmission under reconfigured channel loading. Using this technique we examine a number of channel configurations and system tuning operations for both full-span dispersion-compensated and optimized dispersion-managed systems. For each system design, large power divergence was observed with a maximum of 15 dB at 2240 km, when switching was implemented without additional system tuning. For a bit error rate of 10 3 , the maximum number of loop circulations was reduced by up to 33%.Index Terms-Applied constant gain, circulating loop, EDFA gain dynamics, erbium-doped fiber amplifier (EDFA), reconfigurable WDM networks, simulated constant gain, optically transparent mesh networks, WDM channel power deviation.

Excursion-Free Dynamic Wavelength Switching in Amplified Optical Networks

“…The channel power coupling effect described above grows with a cascade of amplifiers [13], and power divergences of 15 dB were observed in recirculating loop experiments with AGC EDFAs [9]. As a result, the effect of a single reconfiguration event can propagate through the network and cause persistent power excursions and network instability, and even oscillations in the worst case [14,15].…”

“…This issue is particularly acute in mesh metro-area networks, which is characterized by a large number of short amplified ROADM links with many amplifiers. In current generation quasi-static optical transmission systems, power excursions are avoided by using offline planning tools and long reconfiguration times encompassing many adjustments along an optical path [9,16]. This reconfiguration time has to be decreased to the order of seconds in order to enable promising technologies for emerging traffic patterns such as real-time wavelength switched optical bypass, physical layer protection/restoration, and energyefficient transceiver sleep modes.…”

“…While there has been significant work on protocols to enable dynamic wavelength reconfiguration and studies have shown light-path setup times below 3 s [6][7][8], fast wavelength reconfiguration has yet to be implemented at scale in commercial networks. A key unresolved obstacle to implementation is the channel power excursions that arise and propagate throughout a network due to changing channel wavelength configurations in an automatic gain controlled (AGC) optically amplified system [9]. Recent studies on dynamic optical networks either use prereserved wavelengths or assume that the power dynamics problem will be solved-but to date, no comprehensive solution exists [5].…”

Energy challenges in optical access and aggregation networks

“…The hybrid approach creates a platform through which the optics can be programmatically implemented based on the service requirements. An optical connection needs to be established and possibly tuned or conditioned for the signal requirements [48]. Isolating the optical control allows this complexity to be handled separately and thereby facilitates closer inter-working of the two.…”