Single-channel Optical Transmission Research Articles

Revisiting Efficient Multi-Step Nonlinearity Compensation With Machine Learning: An Experimental Demonstration

Efficient nonlinearity compensation in fiber-optic communication systems is considered a key element to go beyond the "capacity crunch''. One guiding principle for previous work on the design of practical nonlinearity compensation schemes is that fewer steps lead to better systems. In this paper, we challenge this assumption and show how to carefully design multi-step approaches that provide better performance--complexity trade-offs than their few-step counterparts. We consider the recently proposed learned digital backpropagation (LDBP) approach, where the linear steps in the split-step method are re-interpreted as general linear functions, similar to the weight matrices in a deep neural network. Our main contribution lies in an experimental demonstration of this approach for a 25 Gbaud single-channel optical transmission system. It is shown how LDBP can be integrated into a coherent receiver DSP chain and successfully trained in the presence of various hardware impairments. Our results show that LDBP with limited complexity can achieve better performance than standard DBP by using very short, but jointly optimized, finite-impulse response filters in each step. This paper also provides an overview of recently proposed extensions of LDBP and we comment on potentially interesting avenues for future work.

Simulation Platform of Optical Transmission System in Matlab Simulink

This paper deals with simulation platform of optical transmission system in Matlab Simulink. A detailed mathematical methodology in order to accurately model parts of optical transmission system is presented. The simulation platform is suitable for simulation single channel optical transmission system. The selected approach takes into account noises that occurs on the parts of optical transmission system.

Analysis of intensity modulation performance in WDM-PON network

This paper mainly does research and analysis on anti-dispersive performance and anti-nonlinear performance for intensity modulation formats such as NRZ, RZ, CS-RZ, DRZ, MD-RZ in 40Gbps high-speed single-channel optical transmission system. It compares the five pattern modulation formats in dispersion tolerance, nonlinear tolerance, and advantages and disadvantages in transmission distance. Anti-nonlinear effect ability of CSRZ and RZ are stronger than that of NRZ code; in the single-channel transmission system, DRZ and improved modulation format MDRZ have better resistance for anti-nonlinear performance, so they are suitable for long-distance transmission. RZ has the minimum dispersion tolerance. NRZ has higher spectrum efficiency than RZ, and thus have a better dispersion tolerance. CSRZ code has higher spectral efficiency, higher dispersion tolerance and nonlinear tolerance than RZ code, making it more suitable for long distance transmission.

Research on the Modulation Performance in GPON System

This paper mainly does research and analysis on anti-dispersive performance and anti-nonlinear performance for intensity modulation formats such as NRZ, RZ, CS-RZ, DRZ, MD-RZ in 40Gbps high-speed single-channel optical transmission system. It compares the five pattern modulation formats in dispersion tolerance, nonlinear tolerance, and advantages and disadvantages in transmission distance. Anti-nonlinear effect ability of CSRZ, RZ are stronger than that of NRZ code; in the single-channel transmission system, DRZ and improved modulation format MDRZ have better resistance foranti-nonlinear performance, so they are suitable for long-distance transmission. RZ has the minimum dispersion tolerance. NRZ than RZ has higher spectrum efficiency than RZ, and thus have a better dispersion tolerance. CSRZ code has higher spectral efficiency, higher dispersion tolerance and nonlinear tolerance than RZ code, making it more suitable for long distance transmission.

Feasibility of 100-Gb/s 10000-km single-channel optical transmission by midway optical phase conjugation incorporated with third-order dispersion compensation

In optical phase conjugation systems, the third-order dispersion of fibers almost linearly accumulates along the transmission distance, and the distortion induced from the third-order dispersion can be perfectly compensated by using a linear third-order dispersion compensator placed at any point of the system. We demonstrate by numerical simulations that 100-Gb/s single-channel transmission can be achieved over a 10000-km distance in midway optical phase conjugation transmission systems by compensating the third-order dispersion.

OA&M framework for multiwavelength photonic transport networks

Photonic networks based on wavelength division multiplexing (WDM) and optical path technologies are expected to realize flexible, transparent, and cost-effective transport networks with a large transmission capacity. This paper explores the design framework of photonic transport networks taking into consideration the operation administration and maintenance (OA&M) functions required for the successful introduction of WDM systems based on the optical path concept. From the view point of network maintenance, clear distinction is made between the optical path layer and the optical section layer to facilitate accurate and smooth failure localization. The digital multiplexing span between physical multiplexing interfaces at the end-to-end digital nodes should have the same maintenance span as the corresponding optical path. We argue that cooperative maintenance by OA&M functions at both the digital and optical layers can be a practical way of network supervision. A supervisory (SV) signal transfer method and a configuration that is suitable for the terrestrial trunk network are also indicated. As an example, a practical SV system design methodology and an actual procedure developed for a single channel optical transmission system based on optical in-line amplifiers are introduced. Furthermore, application of the developed SV system and network restoration schemes is discussed for future WDM-based photonic networks. The OA&M aspects introduced will be valuable for creating future photonic network systems.

1 Tbit/s km transmission experiment at 16 Gbit/s using conventional fibre

We describe a single-channel optical transmission experiment that achieved a bit rate-distance product of 1 Tbit/s Wm over conventional (non-dispersion-shifted) fibre. The transmitter was a directly modulated, 1.3 μm-wavelength, distributed feedback laser. The receiver employed a semiconductor optical preamplifier and a high-impedance pm-HEMT front-end.

Devices for wavelength multiplexing and demultiplexing

Developments of optical fibre communication systems have until recently concentrated on increasing both the distances between repeaters and the intensity modulation bandwidths for single channel optical transmission. Tremendous achievements have been made in both areas such that, in the latter case, it is electronic component limitations which are starting to restrict the speed of operation of experimental systems. In this context, there is renewed interest in wavelength division multiplexing as a technique to upgrade the transmission bandwidth capacities of existing systems together with the possible future provision of broadband multichannel systems. A critical review of the component technology to enable wavelength division multiplexing is therefore useful at this stage. The major implementations of wavelength multiplexer/demultiplexer devices are discussed and compared with particular emphasis placed on their optical efficiency, spectral stability, crosstalk performance and the number of channels that may be provided. Passive devices ranging from the bulk optic implementations (i.e. prisms, gratings, filters) to integrated waveguide and fibre directional coupler realisations are considered. In addition developments associated with active devices including integrated source and detector arrays, wavelength tunable devices and optical amplifiers which may be employed within wave length multiplexed systems are outlined to provide an insight into possible future directions within the field.