Ultra-Wideband Integrated amplifying Device for Enhanced WDM optical systems – UltraWIDE

The project UltraWIDE addresses the issue of increasing the total capacity of wavelength division multiplexing (WDM) systems through a disruptive approach that intends to widen the amplification bandwidth of WDM optical systems. Nowdays, optical fiber communication systems based on WDM widely use erbium doped fibers amplifiers (EDFA), which have a bandwidth limited to approximately 32 nm. The project aims at developing and validating in a system environment a novel optical amplifier with 100nm-large optical bandwidth, so as to leverage the increase of capacity in optical systems by a factor of three.
In the late-90’s, a solution for doubling the optical amplifier bandwidth beyond the conventional C-Band (1530nm-1562nm) was proposed by operating another EDFAs across the L band (1570nm-1602nm) in parallel. This solution was never successful on the market because of its higher complexity, which raised its cost to more than twice the cost of single C-band amplifier. However, the need for larger optical bandwidths is greater than ever.
Project UltraWIDE is therefore timely. It relies on a novel optical amplifier with three times the bandwidth of state-of-art (C-band) amplifier in a single integrated device, which represents a tremendous scientific and technical challenge.
The device incorporates two high-performance optical amplifiers (SOA) imbedded in an innovative integrated structure. Although SOAs have been extensively investigated, they have not been compliant with efficient WDM transmission yet, for the following reasons:
(1) the SOAs developed so far have limited output saturation power (max 17dBm at an injection current of 500mA), especially when designed to be polarization insensitive
(2) the SOAs developed so far have higher noise figures (~7-8dB) than that of EDFAs (5-6dB)
(3) the SOAs developed so far generate cross-talk between WDM channels, whenever the output power is comparable with the saturation power
In UltraWIDE, we rely on an original, polarization-diversity, integrated structure which is used to make a compact and wideband SOA-based amplification device. This structure is expected to alleviate the first two drawbacks. In that respect, the novel optical amplifier has to exhibit comparable performance to that of EDFAs such as such high gains (>20dB), high saturation powers (~25dBm), and satisfactory noise figures (<7dB).
Another important goal of UltraWIDE is to propose and validate original WDM system configurations and node architectures through numerical simulations and experiments (optical power distribution across the WDM multiplex, dispersion mapping, modulation formats, primarily). Even though SOAs have not been able to compete with EDFAs for more than 15 years for WDM amplification, the recent revolutions in system technologies (e.g. FEC and thus nominal operation at higher bit-error-rates, massive expansion of phase shift keying, introduction of coherent detection and powerful signal processing, suppression of in-line dispersion compensation…) make the third drawback (SOA non linear crosstalk) much less critical.
In UltraWide, we propose to demonstrate the transmission of 100Gbit/s channels spanning over 100nm bandwidth, over 1000km distance, i.e. more than a hundredfold improvement from the best demonstrated capacityxdistance product of SOA based transmission systems.
The 6 members of the consortium have complementary skills and expertises to achieve the target. ALU has a strong knowledge of WDM systems and their recent evolutions to draw clear directions, ATL will design specific wide band single polarization SOA with the support of SUP, Kylia will use its free space know how to realize polarization diversity structure. IT will define best operating conditions for advanced SOA in future WDM systems. ENIB will characterize SOA and develop model, while ALU will experimentally demonstrate the added value of 100nm wide band SOA in next generation WDM systems.