Ultra-wideband discrete Raman amplifier optimization for single-span S-C-L-band coherent transmission systems

Abstract

We experimentally compare the performance of two key ultra-wideband discrete Raman amplifier structures, a cascaded dual-stage structure and an in-parallel dual-band structure, in fully loaded S-C-L band coherent transmission systems over 70 km of single-mode fiber. Our results show that dual-band discrete Raman amplifier with minimized backreflections can effectively avoid unstable random distributed feedback lasing, reduce the noise figure, and therefore improve the transmission performance for signals at shorter wavelengths, versus the cascaded dual-stage structure. The average noise figure for S-band signals is 6.8 dB and 7.2 dB for the dual-band structure and cascaded dual-stage structure, respectively, while the average S-band Q2 factor is similarly improved by 0.6 dB. Moreover, the cascaded dual-stage discrete Raman amplifier requires guard bands around the 1485-nm and 1508-nm pumps as the signal and pump wavelengths overlap, which results in a bandwidth loss of ∼10 nm and reduces the potential net data throughput to 28.6 Tb/s for 30-GBaud DP-16QAM signals. However, the dual-band structure can utilize the bandwidth more effectively, which leads to a higher estimated net data throughput of 31.2 Tb/s.

Multi-Band Transmission Over E-, S-, C- and L-Band With a Hybrid Raman Amplifier

“…5, for the DiRA stage, the higher NLI in the E-band is the result of the Raman amplification, which was designed to give gains in that band. A similar trend is observed for the discrete stages, wherein the first stage of the amplifier was designed to give preferential gain in the S-band, while the second stage was designed to give preferential gain in the C and L bands [27].…”

“…A transmission distance of 3040 km over C-and L-band was successfully shown by Krzczanowicz et al, with a dual-stage DRA [25]. Similarly, in the S-, C-and L-band, amplification bandwidths of 150 and 135 nm have also been achieved using a dual-stage and dual-band DRAs [26], [27]. DRAs have also been demonstrated over the E-, S-, C-and L-band, where an amplification bandwidth of 210 nm was achieved and 200 Gbit/s per channel transmission was performed over signals in the range of 1410-1605 nm potentially enabling a transmission bandwidth of 21.8 THz [28], [29].…”

Recent advances in wideband Raman amplifiers

“…The schematics of both these architectures are illustrated in Fig 1, enabling amplification of a full loaded WDM spectrum over a bandwidth of 135 nm. A 30 Gbaud PM-16QAM WDM transmission experiment was performed, in which the dual-band architecture showed an enhanced performance over the dual-stage architecture for the S-band signals with an Q 2 factor improvement of 0.6dB, thus demonstrating relative advantages of the dual-band architecture in improving the transmission performance for the shorter wavelength signals 19 .…”

Characterization of C-Band Coherent Receiver Front-Ends for Transmission Systems Beyond S-C-L-Band

“…In this regard, roadmaps for multi-band (MB) or so-called bandwidth division multiplexing (BDM) systems from O-to U-band (1260-1675 nm) covering 59 THz in bandwidth have gained momentum [3][4][5][6]. While at the same time, the experimental research for single mode fiber is mainly limited to partially filled S-C-L-band systems up to a total bandwidth of 19.8 THz [7][8][9][10], and only recently the first experiments including a coherent reception in the E-band are presented [11], [12]. The mismatch between a full O-U-band system and the current research is partially caused by the unavailability of MB or bespoken per band transponders and hence the inevitable use of wavelength limited C-band componentsoff-the-shelf.…”