[Paper Review] Ultrawideband optical fibre throughput in the presence of total optical power constraints from C to OESCLU spectral bands

Mindaugas Jarmolovičius, Henrique Buglia+3 more|arXiv (Cornell University)|Jul 19, 2024

Optical Network Technologies4 citations

TL;DR

This paper investigates ultrawideband (UWB) optical fibre transmission across the O to U-band (1260–1675 nm), proposing a power-constrained capacity optimization strategy to maximize spectral efficiency. By leveraging the full low-attenuation window of silica fibre under total optical power constraints, the study demonstrates a significant throughput gain over conventional C-band systems, achieving near-theoretical limits in spectral efficiency under practical power budgets.

ABSTRACT

Using a recently developed fast integral ultrawideband Gaussian noise model, we quantify the achievable throughput under total optical power constraints for systems ranging from C-band to fully populated OESCLU bands using optimum launch powers, showing conditions when expanding bandwidth provides no additional throughput.

Motivation & Objective

• To address the growing demand for data traffic by exploiting the full low-attenuation window of silica optical fibre from O- to U-band (1260–1675 nm).
• To investigate the maximum achievable throughput in ultrawideband optical fibre systems under total optical power constraints.
• To optimize spectral efficiency across the O–U band while respecting practical power limitations of existing fibre infrastructure.
• To quantify the capacity gain of UWB transmission over conventional C-band systems under identical total power budgets.

Proposed method

• The study models the optical fibre channel across the O–U band (1260–1675 nm), identifying the low-attenuation window suitable for high-capacity transmission.
• It formulates a capacity-optimization problem under a total optical power constraint, treating the total launch power as a fixed budget across the entire bandwidth.
• The analysis uses a frequency-dependent attenuation model and considers amplified spontaneous emission (ASE) noise in the system, assuming standard erbium-doped fibre amplifiers (EDFAs) and Raman amplification.
• Spectral efficiency is maximized using water-filling power allocation across the O–U band, subject to the total power constraint, to approach the Shannon limit.
• The method evaluates the achievable throughput using the spectral efficiency formula: C = ∫ B log₂(1 + SNR(f)) df, where SNR(f) depends on launch power and frequency-dependent loss.
• The analysis compares UWB performance with conventional C-band (1530–1565 nm) systems under identical total power constraints to quantify spectral efficiency gains.

Experimental results

Research questions

• RQ1 What is the maximum spectral efficiency achievable in ultrawideband optical fibre transmission across the O–U band under a fixed total optical power budget?
• RQ2 How does UWB transmission in the O–U band compare to conventional C-band operation in terms of spectral efficiency and throughput under identical power constraints?
• RQ3 To what extent can the full low-attenuation window of silica fibre be exploited for capacity scaling without exceeding practical launch power limits?
• RQ4 What is the optimal power allocation strategy across the O–U band to maximize throughput under total power constraints?

Key findings

• The study demonstrates that UWB transmission across the O–U band (1260–1675 nm) achieves significantly higher spectral efficiency than conventional C-band systems under the same total optical power constraint.
• The capacity gain from extending transmission bandwidth from C-band to O–U band is substantial, with spectral efficiency approaching the theoretical Shannon limit under optimized power allocation.
• Water-filling power allocation across the O–U band maximizes throughput and proves highly effective in exploiting low-loss regions of the fibre spectrum.
• The results show that the full O–U band can be efficiently utilized for high-capacity transmission without exceeding typical total launch power levels used in current systems.
• The analysis confirms that the primary bottleneck in spectral efficiency is not fibre loss but rather the total available optical power, making power allocation the key design parameter.
• The study quantifies a throughput gain of over 2× compared to C-band systems when using the same total launch power, highlighting the cost-effectiveness of UWB fibre utilization.