Mary Elizabeth McCarthy

Exceeding the Nonlinear-Shannon Limit using Raman Laser Based Amplification and Optical Phase Conjugation

We demonstrate that a combination of Raman laser based amplification and optical phase conjugation enables transmission beyond the nonlinear-Shannon limit. We show nonlinear compensation of 7×114Gbit/s DP-QPSK channels, increasing system reach by 30%.

Capacity limits of systems employing multiple optical phase conjugators

We extend the theory of parametric noise amplification to the case of transmission systems employing multiple optical phase conjugators, demonstrating that the excess noise due to this process may be reduced in direct proportion to the number of phase conjugation devices employed. We further identify that the optimum noise suppression is achieved for an odd number of phase conjugators, and that the noise may be further suppressed by up to 3dB by partial digital back propagation (or fractional spans at the ends of the links).

4 Tb/s Transmission Reach Enhancement Using 10 × 400 Gb/s Super-Channels and Polarization Insensitive Dual Band Optical Phase Conjugation

In this paper, we experimentally demonstrate the benefit of polarization insensitive dual-band optical phase conjugation for up to ten 400 Gb/s optical super-channels using a Raman amplified transmission link with a realistic span length of 75 km. We demonstrate that the resultant increase in transmission distance may be predicted analytically if the detrimental impacts of power asymmetry and polarization mode dispersion are taken into account.

Phase-Conjugated Pilots for Fibre Nonlinearity Compensation in CO-OFDM Transmission

We experimentally demonstrate a novel fibre nonlinearity compensation technique for CO-OFDM based on phase-conjugated pilots (PCPs), showing that, by varying the PCP overhead a performance improvement up to 4 dB can be achieved allowing highly flexible adaptation to link characteristics.

Demonstration of Phase-Conjugated Subcarrier Coding for Fiber Nonlinearity Compensation in CO-OFDM Transmission

In this paper, we demonstrate through computer simulation and experiment a novel subcarrier coding scheme combined with pre-electrical dispersion compensation (pre-EDC) for fiber nonlinearity mitigation in coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. As the frequency spacing in CO-OFDM systems is usually small (tens of MHz), neighbouring subcarriers tend to experience correlated nonlinear distortions after propagation over a fiber link. As a consequence, nonlinearity mitigation can be achieved by encoding and processing neighbouring OFDM subcarriers simultaneously. Herein, we propose to adopt the concept of dual phase conjugated twin wave for CO-OFDM transmission. Simulation and experimental results show that this simple technique combined with 50% pre-EDC can effectively offer up to 1.5 and 0.8 dB performance gains in CO-OFDM systems with BPSK and QPSK modulation formats, respectively.

Electronic dispersion compensation using full optical-field reconstruction in 10Gbit/s OOK based systems

We investigate the design of electronic dispersion compensation (EDC) using full optical-field reconstruction in 10Gbit/s on-off keyed transmission systems limited by optical signal-to-noise ratio (OSNR). By effectively suppressing the impairment due to low-frequency component amplification in phase reconstruction, properly designing the transmission system configuration to combat fiber nonlinearity, and successfully reducing the vulnerability to thermal noise, a 4.8dB OSNR margin can be achieved for 2160km single-mode fiber transmission without any optical dispersion compensation. We also investigate the performance sensitivity of the scheme to various system parameters, and propose a novel method to greatly enhance the tolerance to differential phase misalignment of the asymmetric Mach-Zehnder interferometer. This numerical study provides important design guidelines which will enable full optical-field EDC to become a cost-effective dispersion compensation solution for future transparent optical networks.

Optical and Digital Phase Conjugation Techniques for Fiber Nonlinearity Compensation

We discuss recent progress on the use of optical and digital phase conjugation techniques for nonlinearity compensation in optical fiber links. We compare the achievable performance gain of phase conjugated twin wave applied in two polarization states and time segments with mid-link optical phase conjugation and digital back propagation. For multicarrier transmission scheme such as orthogonal frequency division multiplexing, two recently proposed schemes, namely phase-conjugated pilots and phase-conjugated subcarrier coding are reviewed.

Phase-conjugated pilots for fibre nonlinearity compensation in CO-OFDM transmission

In this paper, we demonstrate a novel fiber nonlinearity compensation technique for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems based on the transmission of phase-conjugated pilots (PCPs). In this scheme, a portion of OFDM subcarriers (up to 50%) is transmitted with its phase conjugates, which is used at the receiver to estimate the nonlinear distortions in the respective subcarriers and other subcarriers, which are not accompanied by PCPs. Simulation and experimental results show that by varying the PCP overhead, a performance improvement up to 4 dB can be achieved. In addition, the proposed technique can be effectively applied in both single polarization and polarization-division multiplexed systems, in both single channel and wavelength-division multiplexing systems, thus, offering highest flexibility in implementations.

Transforming Beef By-products into Valuable Ingredients: Which Spell/Recipe to Use?

Satisfying the increasing global demand for protein results in challenges from a supply perspective. Increased use of animal proteins, through greater use of meat by-products, could form part of the solution, subject to consumer acceptance. This research investigates consumer evaluations of food products that incorporate ingredients derived from offals that have been produced through a range of food processing technologies. Using focus groups incorporating product stimuli representing various combinations of offals, processing, and carrier products, the research finds that the physical state and perceived naturalness of the ingredients influences acceptance. It also highlights the impact of life experiences, linked to demographic characteristics, on interpretations and evaluations of products and processes. Ideational influences, i.e., knowledge of the nature or origin of the substance, are reasons for rejecting some concepts, with misalignment between nature of processing and the product resulting in rejection of others. Lack of perceived necessity also results in rejection. Alignment of ingredients with existing culinary practices and routines, communication of potential sensory, or other benefits as well as naturalness are factors likely to promote acceptance, and generate repeat purchase, in some consumer segments. Trust in oversight that the products are safe is a prerequisite for acceptance in all cases. These findings have implications for pathways to increase sustainability of beef production and consumption through increased use of beef by-products.

Performance limits in optical communications due to fiber nonlinearity

In this paper, we review the historical evolution of predictions of the performance of optical communication systems. We will describe how such predictions were made from the outset of research in laser based optical communications and how they have evolved to their present form, accurately predicting the performance of coherently detected communication systems.