Signal regeneration techniques for advanced modulation formats

We review recent results on all-optical regeneration of phase encoded signals based on phase sensitive amplification achieved by avoiding phase-to-amplitude conversion in order to facilitate the regeneration of amplitude/phase encoded (QAM) signals

In pursuit of knowledge: Addressing barriers to effective conservation evaluation

Evaluation, the process of assessing the effectiveness of programs and activities, has gained increasing attention in the conservation sector as programs seek to account for investments, measure their impacts, and adapt interventions to improve future outcomes. We conducted a country-wide evaluation of terrestrial-based conservation programs in Samoa. Though rarely applied, the benefit of evaluating multiple projects at once is that it highlights factors which are persistent and influential across the entire conservation sector. We found mixed success in achieving goals among conservation programs; yet this result is surrounded by uncertainty because of the quality of existing evidence on project outcomes. We explore the role of different components of the conservation management system, i.e., context, planning, inputs, processes, and outputs, in facilitating and/or constraining collection of data on project outcomes, and thereby assessment of whether projects were successful. Our study identified a number of direct and indirect barriers that affected the capacity of projects to carry out informative evaluations and generate knowledge on conservation progress in Samoa. These attributes and mechanisms include: the availability and management of data, design and planning of projects, and systems for reporting among donors and proponents. To overcome these barriers to evaluation, we believe that a shift in institutional approaches to reporting outcomes is needed, from a reflective way of thinking to a more prospective outlook

SOA-based, idler-free phase quantiser

Energy consumption, system complexity and potential for integration are important factors when considering the suitability of all-optical processing, and depend upon both the scheme used and the medium in which it is performed. We have recently proposed a simple, wavelength-converting phase quantising scheme based on an idler-free phase-sensitive amplifier, notable for its flexibility of operating power and relative compactness [1]. We have demonstrated its performance for QPSK regeneration using an operating power of 24 dBm in 300 m of highly nonlinear fibre (HNLF). Despite offering low loss and high net nonlinearity, the size and geometry of the HNLF do not make it suitable for integration in a photonic device. Semiconductor optical amplifiers (SOAs) on the other hand, offer a particularly compact medium for nonlinear signal processing, combining an amplifier and nonlinear medium in one device. BPSK phase regeneration has been demonstrated in SOAs [2]; in this paper we experimentally demonstrate, to our knowledge, the first realisation of QPSK phase regeneration in SOAs, making use of the above idler-free scheme to realise a compact and more easily integrated QPSK regenerator

PSA-based all-optical multi-channel phase regenerator

We demonstrate simultaneous phase regeneration of six NRZ BPSK signals in a single nonlinear medium using FWM-based phase sensitive amplification. BER measurements confirm OSNR improvement and negligible cross-talk across all the regenerated channels, impaired with broadband phase noise

Investigation into the role of pump to signal power ratio in FWM-based phase preserving amplitude regeneration

We carry out a detailed experimental characterization of a four-wave mixing based amplitude limiter in highly nonlinear fiber based on the Bessel-like power transfer characteristics and highlight trade-offs for phase preserving capabilities

Phase regeneration of QPSK signal in SOA using single-stage, wavelength converting PSA

We demonstrate, for the first time, all-optical phase regeneration of a quaternary phase shift keying (QPSK) signal through phase sensitive amplification (PSA) in nonlinear semiconductor optical amplifiers (SOAs), using a scheme only previously demonstrated in highly nonlinear fibre (HNLF). We make use of a highly tunable phase quantising scheme to circumvent some of the limitations imposed by the use of SOAs and show that it may function in either a conjugating or non-conjugating manner

Phase Regeneration of QPSK Signal in SOA Using Single-Stage, Wavelength Converting PSA

We demonstrate, for the first time, all-optical phase regeneration of a quaternary phase shift keying (QPSK) signal through phase sensitive amplification (PSA) in nonlinear semiconductor optical amplifiers (SOAs), using a scheme only previously demonstrated in highly nonlinear fibre (HNLF). We make use of a highly tunable phase quantising scheme to circumvent some of the limitations imposed by the use of SOAs and show that it may function in either a conjugating or non-conjugating manner

Trends and biases in the listing and recovery planning for threatened species: an Australian case study

Many countries rely on formal legislation to protect and plan for the recovery of threatened species. Even though the listing procedures in threatened species legislation are designed to be consistent for all species there is usually a bias in implementing the laws towards charismatic fauna and flora, which leads to uneven allocation of conservation efforts. However, the extent of bias in national threatened species lists is often unknown. Australia is a good example: the list of threatened species under the Environmental Protection and Biological Conservation Act has not been reviewed since 2000, when it was first introduced. We assessed how well this Act represents threatened species across taxonomic groups and threat status, and whether biases exist in the types of species with recovery plans. We found that birds, amphibians and mammals have high levels of threatened species (12-24%) but < 6% of all reptiles and plants and < 0.01% of invertebrates and fish are considered threatened. Similar taxonomic biases are present in the types of species with recovery plans. Although there have been recent improvements in the representation of threatened species with recovery plans across taxonomic groups, there are still major gaps between the predicted and listed numbers of threatened species. Because of biases in the listing and recovery planning processes many threatened species may receive little attention regardless of their potential for recovery: a lost opportunity to achieve the greatest conservation impact possible. The Environmental Protection and Biological Conservation Act in Australia needs reform to rectify these biases

FWM-based, Idler-free Phase Quantiser with Flexible Operating Power

Coherently adding a signal's conjugate and third harmonic at the latter's wavelength enables phase quantisation across a large operating power range. With broadband phase noise, a 5.6dB QPSK receiver sensitivity improvement is achieved with BER=10-4