Excursion-Free Dynamic Wavelength Switching in Amplified Optical Networks

Abstract

Dynamic optical networking with rapid wavelength reconfiguration is a promising capability to support the heterogeneous, bursty traffic rapidly growing in metroarea networks. A major obstacle to realizing dynamicity in the optical layer is the channel power excursions that occur due to continuously changing input conditions into gain controlled optical amplifiers. Here we present a technique of distributing an optical signal across multiple wavelengths chosen to reduce or cancel the power dynamics so that excursion-free switching can be achieved in an optically amplified transparent network. The use of variable wavelength dwell times for excursion-free switching using arbitrary wavelength pairs is presented. Spectral efficiency lost in utilizing multiple wavelengths is recovered through time-division multiplexing two signals distributed over the same wavelengths.

Dual Laser Switching for Dynamic Wavelength Operation in Amplified Optical Transmission

“…this effect has been thoroughly characterized for automatic gain controlled (AGC) amplifiers and shown to grow along an amplifier cascade while diminishing with larger channel loading, as wavelength dependent variations are averaged out [5]. Using two laser sources with an electro-optical switch to select between them within a single transceiver, a single channel power can be distributed over multiple wavelengths such that the excursion of these wavelengths can be reduced or canceled out [4]. When the switching period over these two wavelengths is faster than AGC control response time (on the order of 100 s or slower), there are no transient effects associated with this switching and such wavelength pairs can be provisioned without disturbing other channels in the system.…”

“…Recent studies have looked at wavelength assignment algorithms based on the channel power interactions [2] and machine learning methods to select wavelengths based on historical performance information [3]. Fast laser source switching was shown to reduce and by duty cycle tuning remove power excursions [4]. In this paper, transmission of 100 Gb/s PM-QPSK signals using this fast laser switching technique by incorporating a laser pair at the source and local oscillator is studied through experiment and simulation.…”

Dual-wavelength source based optical circuit switching and wavelength reconfiguration in multi-hop ROADM systems

“…Dual-wavelength sources efficiently reduce the power excursions, with the maximum power excursion less than or equal to ± 1.5 dB 99% of the time and ± 0.5 dB 71.4% of the time for the network considered here, but using multiple dual-switching channels may quickly use up all available wavelengths and reduce the spectral efficiency in a heavily loaded system. One potential solution is time-division multiplexing (TDM), distributing another pair with the same two wavelengths but at disjoint time slots [16]. However, this approach requires a precise global clock to synchronize all laser sources.…”

“…Using a fast tunable laser to distribute a single signal over two or more wavelengths with different wavelength dependent gains is also a promising way to minimize the power excursions. By adjusting the duty ratio of the fast tuning between two wavelengths, less than 0.1 dB power excursion was achieved on measured channels in a three cascading EDFA single-hop system [16]. However, its data transmission performance in a multi-hop ROADM transmission system with dynamic wavelength reconfiguration has yet to be explored.…”

Dynamic mitigation of EDFA power excursions with machine learning

“…Dynamic workloads such as video streaming, Internet of Things (IoT), and cloud computing require optical networks to handle growing traffic demands with agility and resilience to faults [1,2]. As a result, traditional quasi-static networks must be reconfigured in real-time to deliver network resources and the required quality of service (QoS) [3].…”