Modeling of Ultra-Long Span Bidirectional Raman Transmission Link Using Three-Segment Hybrid Fiber Core Structure

Abstract

Ultra-long span unrepeatered systems using distributed Raman amplification are cost-effective solutions for bridging moderate transmission distances. However, there are two major limiting factors: nonlinear Kerr effect-induced nonlinear signal distortion and optical signal-to-noise ratio degradation due to spontaneous Raman noise. In this report, we proposed a model of three-segment hybrid fiber effective core area structure and developed a model covering: (1) generalized mathematical formulations, (2) analysis of three-segment Raman amplified link, and (3) simulation model of data transmission. The proposed model showed an improvement of the Raman gain profile, a reduction of the negative impact of the nonlinear Kerr effect, and an enhancement of the optical signal-to-noise ratio. A numerical simulation of the transmission performance of the three-segment hybrid structure was compared to conventional single-segment single fiber core structure on 80 Gb/s differential quadrature phase-shift keying (DQPSK) modulated data signals over a propagation distance of 390 km. The required optical signal-to-noise ratio was reduced by 2.71 dB to achieve the target error rate without using forward error correction. The numerical model and simulation of various data rates up to 100 Gb/s consistently showed that an improvement in transmission performance could be achieved by using three-segment hybrid fiber effective core area structure.

Modelling of gain profiles and Raman lasing in TiO2/GeO2-doped silica fibres

“…Indeed, the use of single ultra-long-span links as long as several hundred kilometres is extended steadily. It is firmly confirmed [3] that ultra-long-span unrepeated systems that employ distributed Raman amplifiers represent a simple and cost-effective solution that does not require active in-line components. The transmission performance can be enhanced by improvements in the design of fibre-optic core and material characteristics [4], including the fibres with large effective-core area [5] and very low-loss fibres [6].…”