System and method for multi-mode optical fiber

A multi-mode optical fiber includes alternating cores have positive and negative differential mode delays over a range of wavelengths

Channel Coding Gains in High Throughput and Long Reach Optical Transmission Systems

— The main objectives of the project is the investigation of two main types of coding schemes with the aim of maximizing optical signal to noise ratio (OSNR) gains in long reach optical transmission systems. The project will start with a study of the various coder/decoder schemes followed by the identification of the main types e.g. direct mapping schemes and/or Trellis Coded Modulation schemes for Quadrature Phase Shift Keying (QPSK). Trellis coded modulation (TCM) and parallel concatenated (PC)-TCM. A TCM encoder and decoder were created and its performance simulated for bit error rate (BER) against various signal to noise ratio (SNR) measurements. A sequence for the setup was created, transmitted and successfully decoded. A TTCM encoder and decoder were created. Further tuning is needed for the TTCM decoder However, implemented coders also require investigation and implementation of algorithms required for the decoders (e.g. Viterbi and Forward backward algorithm). Finally, the implemented encoder/decoder schemes are evaluated in an 112Gbit/s QPSK/8PSK single mode fiber recirculating loop setup for BER and OSNR validation

Low-complexity pre-compensation and advanced modulation techniques for high capacity intensity-modulated direct detection systems

Digital signal processing (DSP) is key for high-speed intensity-modulation direct detection (IM/DD) data center connections. In this Master thesis, the challenges in designing high-speed data center interconnects (DCIs), such as limited bandwidth and chromatic dispersion, are explained, important digital algorithms for dealing with this challenges are discussed and the implementation of these algorithms is verified with five cutting-edge optical transmission experiments. The importance and success of this work is emphasized by three accepted paper submissions to an international conference

Dispersion optimised impairment constraint based routing and wavelength assignment algorithms for all-optical networks

Current methods in the area of impairment constraint based routing algorithms (ICBRA) lack the capabilities to support information regarding dispersion management. The inclination towards higher bit-rates and heterogeneous optical networks in the future challenges the popular assumption that chromatic dispersion (CD) is adequately compensated on a per-link basis. Recognising the importance of dispersion management, this paper proposes algorithms which apply metrics that contain dispersion information to both the routing and wavelength assignment sub-problems. To the best of our knowledge, this is the first attempt to include dispersion information within the wavelength assignment sub-problem. The newly proposed algorithm is named dispersion optimised impairment constraint-based RWA (DOIC). The performance is compared to existing routing and wavelength techniques under two scenarios: 40 Gb/s and mixed 10 Gb/s/40 Gb/s services. Two physical impairments under investigation are chromatic dispersion (CD) and optical signal to noise ratio (OSNR

Performance analysis of an optical packet switch with shared parametric wavelength converters

Wavelength conversion capability has been shown to significantly improve the blocking performance of all-optical networks. In order to transport payloads that may be of different bit-rates and modulation formats, a transparent wavelength conversion method is desirable. Recently, parametric wavelength converters, that are capable of multi-channel wavelength conversion for heterogeneous optical services, have been experimentally demonstrated for optical circuits. In this letter, we analyse the performance of an asynchronous optical packet-switch (OPS) architecture that exploits such devices. A sensitivity analysis of the number of converters, as a function of the main switch design parameters, demonstrate a significant reduction in the number of converters when compared with architectures employing single- channel wavelength conversion

Polarization-ring-switching for nonlinearity-tolerant geometrically-shaped four-dimensional formats maximizing generalized mutual information

In this paper, a new four-dimensional 64-ary polarization ring switching (4D-64PRS) modulation format with a spectral efficiency of $6$~bit/4D-sym is introduced. The format is designed by maximizing the generalized mutual information (GMI) and by imposing a constant-modulus on the 4D structure. The proposed format yields an improved performance with respect to state-of-the-art geometrically shaped modulation formats for bit-interleaved coded modulation systems at the same spectral efficiency. Unlike previously published results, the coordinates of the constellation points and the binary labeling of the constellation are \emph{jointly} optimized. When compared against polarization-multiplexed 8-ary quadrature-amplitude modulation (PM-8QAM), gains of up to $0.7$~dB in signal-to-noise ratio are observed in the additive white Gaussian noise (AWGN) channel. For a long-haul nonlinear optical fiber system of $8,000$~km, gains of up to $0.27$~bit/4D-sym ($~5.5$\% data capacity increase) are observed. These gains translate into a reach increase of approximately $16\%$ ($1,100$~km). The proposed modulation format is also shown to be more tolerant to nonlinearities than PM-8QAM. Results with LDPC codes are also presented, which confirm the gains predicted by the GMI

Increasing achievable information rates via geometric shaping

\u3cp\u3eAchievable information rates are used as a metric to design novel modulation formats via geometric shaping. The proposed geometrically shaped 256-ary constellation achieves SNR gains of up to 1.18 dB.\u3c/p\u3

Four-dimensional polarization-ring-switching for dispersion-managed optical fibre systems

The recently introduced 4D 64-ary polarisation-ring-switching format is investigated in dispersion-managed systems. Numerical simulations show a reach increase of $25\%$ with respect to PM-8QAM. This gain is achieved from the nonlinear tolerance of the format and a 4D demapper using correlated noise assumptions

Eight-dimensional polarization-ring-switching modulation formats

We propose two 8-dimensional (8D) modulation formats (8D-2048PRS-T1 and 8D-2048PRS-T2) with a spectral efficiency of 5.5 bit/4D-sym, where the 8 dimensions are obtained from two time slots and two polarizations. Both formats provide a higher tolerance to nonlinearity by selecting symbols with nonidentical states of polarization (SOPs) in two time slots. The performance of these novel 8D modulation formats is assessed in terms of the effective signal-to-noise ratio (SNR) and normalized generalized mutual information. 8D-2048PRS-T1 is more suitable for high SNRs, while 8D-2048PRS-T2 is shown to be more tolerant to nonlinearities. A sensitivity improvement of at least 0.25 dB is demonstrated by maximizing normalized generalized mutual information (NGMI). For a long-haul nonlinear optical fiber transmission system, the benefit of mitigating the nonlinearity is demonstrated and a reach increase of 6.7% (560 km) over time-domain hybrid four-dimensional two-amplitude eight-phase shift keying (TDH-4D-2A8PSK) is observed

Polarization-ring-switching for nonlinearity-tolerant geometrically-shaped four-dimensional formats maximizing generalized mutual information

In this paper, a new four-dimensional 64-ary polarization ring switching (4D-64PRS) modulation format with a spectral efficiency of 6 bit/4D-sym is introduced. The format is designed by maximizing the generalized mutual information (GMI) and by imposing a constant modulus on the 4D structure. The proposed format yields an improved performance with respect to state-of-the-art geometrically shaped modulation formats for bit-interleaved coded modulation systems at the same spectral efficiency. Unlike previously published results, the coordinates of the constellation points and the binary labeling of the constellation are jointly optimized. When compared with polarization-multiplexed 8-ary quadrature-amplitude modulation (PM-8QAM), gains of up to 0.7 dB in signal-to-noise ratio are observed in the additive white Gaussian noise channel. For a long-haul nonlinear optical fiber system of 8,000 km, gains of up to 0.27 bit/4D-sym (5.5% data capacity increase) are observed. These gains translate into a reach increase of approximately 16% (1,100 km). The proposed modulation format is also shown to be more tolerant to nonlinearities than PM-8QAM. Results with low-density parity-check codes are also presented, which confirm the gains predicted by the GMI