Radio-frequency spectrum coding in ultra-long fibre laser based cryptography

We propose a new approach for secret key exchange involving the variation of the cavity length of an ultra-long fibre laser. The scheme is based on the realisation that the free spectral range of the laser cavity can be used as an information carrier. We present a proof-of-principle demonstration of this new concept using a 50-km-long fibre laser to link two users, both of whom can randomly add an extra 1-km-long fibre segment.

Optimisation of random DFB Raman laser amplifier

We numerically optimise 2nd-order random DFB Raman laser amplifiers for transmission for the first time. Optical signal to noise ratio, nonlinear phase shift, signal power variation and the impact of the reflectivity of FBG are investigated in the links from 10 - 120 km.

Advanced 3R regenerator scheme for high spectral efficient signal waveforms

We propose a novel 3R regenerator architecture for highly spectral efficient signals. Through numerical simulations we evaluate its performance and compare with traditional 2R schemes. The results of the analysis demonstrate necessity of 3R for regeneration of NRZ pulses and its relevance for future high capacity transmission systems.

Design of nonlinear regenerative transmission systems with high capacity

We present the design of nonlinear regenerative communication channels that have capacity above the classical Shannon capacity of the linear additive white Gaussian noise channel. The upper bound for regeneration efficiency is found and the asymptotic behavior of the capacity in the saturation regime is derived. © 2013 IEEE.

DISCUS : end-to-end network design for ubiquitous high speed broadband services

Fibre-to-the-premises (FTTP) has been long sought as the ultimate solution to satisfy the demand for broadband access in the foreseeable future, and offer distance-independent data rate within access network reach. However, currently deployed FTTP networks have in most cases only replaced the transmission medium, without improving the overall architecture, resulting in deployments that are only cost efficient in densely populated areas (effectively increasing the digital divide). In addition, the large potential increase in access capacity cannot be matched by a similar increase in core capacity at competitive cost, effectively moving the bottleneck from access to core. DISCUS is a European Integrated Project that, building on optical-centric solutions such as Long-Reach Passive Optical access and flat optical core, aims to deliver a cost-effective architecture for ubiquitous broadband services. One of the key features of the project is the end-to-end approach, which promises to deliver a complete network design and a conclusive analysis of its economic viability. © 2013 IEEE.

Performance evaluation of strongly filtered asymmetric 42.7 Gb/s coherent 50%RZ-BPSK system

We show, by numerical simulation, that the impact of tight optical filtering in high speed coherent 50% RZ-BPSK systems can be greatly reduced by offsetting the filter (equivalent to laser detuning). We show that by offsetting the filter by up to half the filter bandwidth, that system performance is improved by > 2.5 dB in the calculated 'Q' for an OSNR of 12 dB. © 2013 IEEE.

Performance enhancement of partial-42.7 Gb/s DPSK via an asymmetrical receiver design

We present numerically and experimentally the combined impact of an asymmetric receiver design and a partial 42.7 Gb/s DPSK system. By implementing an optimized bit period delay at the MZI and Asymmetric filtering at the destructive port, system performance can be significantly improved by 1.8 dB for an OSNR of 20 dB. © 2013 IEEE.

Reflection of a spatial-temporal airy pulse from a layer

The interaction of an Airy pulse with a dielectric layer is investigated theoretically. Approximate analytical expressions for reflected and transmitted waves are derived in the form of Taylor series. These series consist of shifted Airy pulses which are decelerated in time and space and deceleration becomes stronger with a number of a term of series. © 2012 IEEE.

Capacity of dispersion-non-compensated nonlinear fibre channels

We present the analytical description of a specific nonlinear fibre channel with non-compensated dispersion. Information theory analysis shows that capacity of such nonlinear fibre channel does not decay with growing signal-to-noise ratio. © 2012 IEEE.

Evaluation on a 60 GHz radio over fiber system employing photonic up conversion and optically beam formed linear array antenna for broadband indoor access

In this study, two linear coplanar array antennas based on Indium Phosphide (InP) substrate are designed, presented and compared in terms of bandwidth and gain. Slot introduction in combination with coplanar structure is investigated, providing enhanced antenna gain and bandwidth at the 60 GHz frequency band. In addition the proposed array antennas are evaluated in terms of integration with a high-speed photodiode and investigated in terms of matching, providing a bandwidth that reaches 2 GHz. Moreover a potential beam forming scenario combined with photonic up-conversion scheme has been proposed. © 2013 IEEE.

Cost-efficient OFDM generation at 60-GHz by heterodyne technique with direct modulation and envelope detector

A cost-effective radio over fiber system to up-convert and transmit multigigabit signals at 60 GHz is presented. A low intermediate frequency OFDM signal is used to directly modulate a laser, which is combined with an independent unmodulated laser. The generated millimeter wave frequency can be adjusted by tuning the frequency separation between the lasers. Since no external modulator is required, this technique is low-cost and it is easily integrable in a single chip. In this paper, we present numerical results showing the feasibility of generating an IEEE 802.15.3c compliant 3.5-Gbps 60-GHz OFDM. We show that received signal quality is not limited by the lasers' linewidth but by the relative intensity noise. © 2013 IEEE.

Quantitative comparison of low-cost OFDMA-PON transceiver implementations

A quantitative comparison of up to 40 Gb/s low-cost orthogonal frequency-division multiplexing access (OFDMA)-passive optical networks (PON) implementations for both upstream (US) and downstream (DS) directions is evaluated based on different modulation and detection techniques. © 2012 IEEE.

Stochastic calculations for fibre Raman amplifiers with randomly varying birefringence

For the first time for the model of real-world forward-pumped fibre Raman amplifier with the randomly varying birefringence, the stochastic calculations have been done numerically based on the Kloeden-Platen-Schurz algorithm. The results obtained for the averaged gain and gain fluctuations as a function of polarization mode dispersion (PMD) parameter agree quantitatively with the results of previously developed analytical model. Simultaneously, the direct numerical simulations demonstrate an increased stochastisation (maximum in averaged gain variation) within the region of the polarization mode dispersion parameter of 0.1÷0.3 ps/km1/2. The results give an insight into margins of applicability of a generic multi-scale technique widely used to derive coupled Manakov equations and allow generalizing analytic model with accounting for pump depletion, group-delay dispersion and Kerr-nonlinearity that is of great interest for development of the high-transmission-rates optical networks.

Polarisation phenomena in mode locked fibre lasers and fibre Raman amplifiers griffon tutorial

For a fibre Raman amplifier with randomly varying birefringence, we provide insight on the validity of previously explored multi-scale techniques leading to polarisation pulling of the signal state of polarisation to the pump state of polarisation. Unlike previous study, we demonstrate that in addition to polarisation pulling a new random birefringence-mediated phenomenon that goes beyond existing multi-scale techniques can boost resonance-like gain fluctuations similar to the Stochastic Anti-Resonance. For mode locked fibre lasers we report on fast and slow polarisation dynamics of fundamental, bound state, and multipulsing vector solitons along with stretched pulses. We demonstrate that tuning cavity anisotropy and birefringence along with parameters of an injected signal with randomly varying state of polarisation provides access to the variety of vector waveforms previously unexplored.

Time-varying airy pulses

Pulses in the form of the Airy function as solutions to an equation similar to the Schrodinger equation but with opposite roles of the time and space variables are derived. The pulses are generated by an Airy time varying field at a source point and propagate in vacuum preserving their shape and magnitude. The pulse motion is decelerating according to a quadratic law. Its velocity changes from infinity at the source point to zero in infinity. These one dimensional results are extended to the 3D+time case for a similar Airy-Bessel pulse with the same behaviour, the non-diffractive preservation and the deceleration. This pulse is excited by the field at a plane aperture perpendicular to the direction of the pulse propagation. © 2011 IEEE.