Optical Fibre Capacity Optimisation via Continuous Bandwidth Amplification and Geometric Shaping

Abstract

The maximum data throughput in a single mode optical fibre is a function of both the signal bandwidth and the wavelength-dependent signal-to-noise ratio (SNR). In this paper, we investigate the use of hybrid discrete Raman & rare-earth doped fibre amplifiers to enable wide-band signal gain, without spectral gaps between amplification bands. We describe the widest continuous coherent transmission bandwidth experimentally demonstrated to date of 16.83 THz, achieved by simultaneously using the S-, C-and L-bands. The variation of fibre parameters over this bandwidth, together with the hybrid amplification method result in a significant SNR wavelengthdependence. To cope with this, the signal was optimised for each SNR, wavelength and transmission band. By using a system-tailored set of geometrically shaped constellations, we demonstrate the transmission of 660⇥25 GBd channels over 40 km, resulting in a record single mode fibre net throughput of 178.08 Tbit/s. Index Terms-Broadband transmission system, high order modulation format, geometric shaping.

Widely Linear Filtering for Multiimpairment Compensation in Dispersion Managed mQAM Modulated Optical Systems

“…Non-idealities such as phase imbalance and gain imbalance are introduced in the IQ modulator (Transmitter IQ Imbalance), as described in Eqn. (1) to study the effect of the same on the signal after transmission. Polarization transformation is modelled using the Jones matrix [30] and power loss in the system is compensated by an Erbium doped fiber amplifier (EDFA).…”

“…The capacity of fiber optic communication systems is being scaled with higher-order modulation formats, multi-carrier modulations and with the use of wavelength and space division multiplexing schemes. In the case of single-carrier systems, the data rates can be increased by employing higher-order modulation formats coupled with advanced equalization algorithms implemented through digital signal processing (DSP) [1]. Despite the progress made in recent years on increasing the end-to-end signal-to-noise ratio (SNR) of transmission systems so that they are compatible with higher-order QAM formats, the generation and detection of ultra-high order QAM signals remain challenging [2].…”

Multi-Band Photonic Integrated Wavelength Selective Switch

“…MBT systems are already being deployed as C+L [4], [5], by capitalizing on the re-use of erbium-doped fiber amplifiers (EDFAs) also within the L-band. More recently, S+C+L-band systems started being subject of active research, from numerical studies [3], [6] that showed the potential of these three-band systems to triple the capacity when compared against C-band only, to experimental setups employing power optimization schemes [5], wideband semiconductor optical amplifiers (SOAs) [7], [8] and continuous bandwidth amplification and geometric shaping for record breaking data transmission [9]. As MBT systems gain commercial traction, solutions for, e.g., spectrum management and routing are required.…”

Challenges in Extending Optical Fibre Transmission Bandwidth Beyond C+L Band and How to Get There

“…Different types of amplification schemes, such as Raman amplification, rare-earth doped fibre amplifiers and semiconductor optical amplifiers (SOA) have been used to expand optical fibre transmission window. Figure 1 illustrates the total throughput achieved by these technologies whether used alone or in combination [1]. Using Raman amplifiers and rare-earth doped fibre amplifiers, we demonstrated the world record transmission of 178.08 Tbit/s over 40 km [1].…”

“…Figure 1 illustrates the total throughput achieved by these technologies whether used alone or in combination [1]. Using Raman amplifiers and rare-earth doped fibre amplifiers, we demonstrated the world record transmission of 178.08 Tbit/s over 40 km [1]. This achievable throughput was obtained by simultaneously transmitting 16.83 THz bandwidth at the S-, C-and L-bands, together with adaptive modulation formats tailored with the received SNR and geometric shaping (GS), aiming to maximize the total throughput.…”