image: Gain/NF characteristics of single-stage vs dual-stage at (a) -25 dBm input power; (b) -10 dBm input power; (c) 5 dBm input power; (d) 2nd stage pump power vs output power at 1428 nm for all input powers.
Credit: Shabnam Noor, Aston Institute of Photonic Technologies
As demand for high-bandwidth applications grows, there is an urgent need to increase the data-carrying capacity of optical communication networks. In a new study, researchers show that a bismuth-doped fiber amplifier they developed could be a promising solution for meeting this need by enhancing the range and flexibility of optical networks.
Experiments with the dual-stage E+S-band bismuth-doped fiber amplifier revealed an unprecedented combination of broad bandwidth, high gain and low noise, making it well-suited for boosting optical signals in next-generation optical communication systems.
Shabnam Noor from Aston Institute of Photonic Technologies in the UK will present this research at OFC, the premier global event for optical communications and networking, which will take place 30 March – 03 April 2025 at the Moscone Center in San Francisco.
“This study makes important advancements in multi-band amplification and moves us closer to realizing such devices in the systems that impact our daily lives,” said John Ballato, Clemson University, USA, OFC Subcommittee Chair.
Multi-band transmission (MBT) is one solution being explored to improve optical communication networks. This approach improves existing infrastructure by tapping into bandwidth beyond traditional C- and L-bands. MBT systems have shown impressive results by using advanced amplification technologies, such as bismuth-doped fiber amplifiers (BDFAs), to unlock wider transmission windows without requiring new fiber installations.
In their paper, the researchers focused on improving BDFA performance in the E-band (1360-1460 nm) and S-band (1460-1530 nm), with a particular emphasis on using a dual-stage design to enhance the gain bandwidth in the S-band. For the first time, they demonstrate a dual-stage BDFA with 104 nm maximum bandwidth (1384-1488nm), 47 dB maximum gain and a 3.7 dB minimum noise figure.
The device’s two amplification stages are identical and use thin-film filter wavelength division multiplexers to multiplex and demultiplex the input signal (1384-1522 nm) and pump radiation (1320 nm). A 100-m long active Bi-doped germanosilicate fiber is used in each stage of the amplifier.
Wavelength division multiplexing combines multiple signals into one fiber for transmission while demultiplexing separates them back into individual signals at the receiving end.
The researchers say that this demonstration paves the way for further improvement using gain flattening filters (GFF), enabling the amplifiers to be used in regional and long-haul networks to compensate for extra losses introduced by reconfigurable optical add-drop multiplexers (ROADMs).
“The immediate next steps for this research will involve further optimization via the use of full spectral load and lower power per channel, as well as a mid-stage GFF,” said Noor. “In the future, transmission experiments with fully loaded E+S bands will be carried out.”
The OFC Technical Conference will feature over 650 high impact, peer-reviewed scientific presentations, including this one, starting on Sunday, 30 March.
About OFC
The 2025 Optical Fiber Communication Conference and Exhibition (OFC) is the premier conference and exhibition for optical communications and networking professionals. For 50 years, OFC has drawn attendees from all corners of the globe to meet and greet, teach and learn, make connections and move business forward.
OFC includes dynamic business programming, an exhibition of global companies and high impact peer-reviewed research that, combined, showcase the trends that are shaping the entire optical networking and communications industry. OFC is co-sponsored by the IEEE Communications Society (IEEE/ComSoc) and the IEEE Photonics Society and co-sponsored and managed by Optica. OFC will be held in-person, 30 March – 03 April 2025, at the Moscone Center, San Francisco, California, USA, with on-demand access to content available post-conference. All technical sessions, workshops, panels and exhibit floor sessions—with speaker permission—will be accessible to Full Conference registrants.
Learn more and engage on LinkedIn, follow @OFCConference on X and watch highlights on OFC’s YouTube channel.