Dispersion uncompensated IM/DD transmissions of 12GHz-wide multi-band OFDM over 100km with a D-EML

International audienceGeneration of optical SSB signals by a D-EML is extended to its whole bandwidth. In an SSB context, 12GHz multi-band OFDM signal is transmitted through 100km intensity modulation/direct detection dispersive channel without frequency fading

Quantum dash based directly modulated lasers for long-reach access networks

International audienceWe demonstrate an innovative 10 Gbps single mode optical transmitter with the capacity of error free transmission in the range of 0 to 100kms with constant biasing conditions using a Quantum Dash Directly Modulated Laser. We use a commercially available etalon filter as passive optical filter to achieve penalty free transmission with a dynamic extinction ratio (DER) > 6dB over a large range of fiber spans

Comparison of Digital Signal Processing Approaches for Subcarrier Multiplexed 5G and Beyond Analog Fronthaul

Analog fronthaul transport architectures with digital signal processing at the end stations are promising as they have the potential to achieve high spectral efficiencies, increased flexibility and reduced latency. In this paper, two digital techniques for frequency domain multiplexing/de-multiplexing large numbers of channels are contrasted: one operates on the pre-Inverse Fast Fourier Transform (IFFT) “frequency-domain” samples while the other does so on the post-IFFT “time-domain” samples. Performance criteria including computational complexity and sampling rate requirements are used in the comparison. Following modeling and simulation of the techniques, implemented within a radio-over-fiber transport architecture, error vector magnitude performance estimates are obtained. These results show that each technique has performance advantages under specific channel transport scenarios

Silicon-on-Insulator RF Filter Based on Photonic Crystal Functions for Channel Equalization

International audienceA compact silicon-on-insulator 2-tap interferometer is demonstrated as a channel equalizer. The radiofrequency filter is reconfigurable thanks to thermally-controlled photonic crystal couplers and delay lines. The channel fading of a dispersive fiber link supporting a directly modulated telecommunication signal is successfully compensated for using the interferometer, leading to eye diagram opening and the possibility to recover the bit-error-rate of a reference signal with less than 1-dB power penalty

Flexible and Efficient DSP-assisted Subcarrier Multiplexing for an Analog Mobile Fronthaul

The digital formation of an analog subcarrier multiplex employing in combination both a technique using pre-IFFT frequency-domain samples and one using post-IFFT time-domain samples is proposed and demonstrated. This combined technique enables a compromise for sampling rate requirements, while maintaining low complexity and good performance

IQ Imbalance Compensation Based on Maximum SNR Estimation in Coherent QPSK Systems

International audienceWe present a simple alternative method for the compensation of quadrature imbalance in optical quadrature phase-shift-keying (QPSK) coherent systems. The method is based on the determination and the compensation of the phase mismatch by the introduction of a relevant signal-to-noise ratio metric. The principle is validated numerically and the algorithm is validated experimentally through bit-error-rate (BER) and error vector magnitude (EVM) measurements. A 20 Gb/s optical QPSK experiment reveals a good agreement of theproposed method with the Gram-Schmidt orthogonalization procedure (GSOP). Moreover, the robustness of both methods was verified with up to 30° phase misalignment by comparing the signal after phase imbalance compensation to that without compensation. A 10% reduction of EVM is achieved with our method for a high phase misalignment of 30°

OFDM signal transmission over polymer optical fibers using LEDs

O presente trabalho tem como objetivo apresentar a transmissão de sinais OFDM (Orthogonal Frequency Division Multiplexing) em fibras plásticas multimodo com índice degrau (SI Multimode POFs Step Index Multimode Polymer Optical Fibres) utilizando LEDs (Light Emitting Diodes) que não são otimizados para aplicações de dados. Este esquema representa uma interessante alternativa para o aumento da eficiência espectral do sistema tendo em vista que a banda passante dos emissores utilizados é muito baixa. Além disso, é também um eficiente mecanismo de combate às dispersões presentes nas fibras multimodo, principalmente a modal. As transmissões realizadas neste projeto foram feitas através da modulação direta do LED e detecção não-coerente com um fotodiodo do tipo PIN com pré-amplificação. Taxas de até 47 Mbits/s por comprimento de onda foram conseguidas em 100 m de enlace utilizando-se LEDs que emitem nos espectros de luz visível vermelho, verde e azul e para uma banda passante média de 15 MHzThis work presents the transmission of an OFDM (Orthogonal Frequency Division Multiplex) signal through a multimode Step-Index Polymer Optical Fibre (SI-POF) using ultra brilliant LEDs which are not optimized for data applications. This modulation scheme can be an interesting alternative to increase the spectral efficiency of the system considering the low passing band of the emitters which were used. In addition, it is also an efficient mechanism to combat fiber dispersions which are dominated by intermodal phenomena. The transmissions showed in this project were based on direct modulation of the emitter and non-coherent detection with a PIN photodiode with pre-amplification. Bit rates of up to 47 Mbits/s per wavelength are shown for a 100 m link using LEDs that emit on corresponding red, green and blue spectra of visible light and with a mean passing band of 15MHz123 p

Study of the potentialities of multicarrier modulation techniques for future WDM and TDM passive optical access networks

Malgré son succès dans le domaine des radio-fréquences, l OFDM n a que récemment commencé à attirer l attention de la communauté optique grâce à une remarquable évolution de l électronique et aux demandes de débit de plus en plus élévées dans les réseaux d accès. OFDM apparaît comme un très fort candidat pour fournir la flexibilité tant attendue dans les réseaux d accès optiques "rigides" d aujourd hui ayant aussi le potentiel de permettre une évolution vers des débits, portées et nombre d abonnés plus élévés. Dans cette thèse, nous nous concentrons sur une approche de modulation en intensité et détection directe (IMDD) qui permet de conserver la simplicité sur le plan optique en transférant la complexité de la transmission au domaine du traitement numérique du signal. Ce travail se base sur deux axes principaux. Dans le premier, nous étudions l influence de la réponse fréquentielle du canal, caracterisée par l interaction entre la dispersion chromatique de la fibre optique et la modulation parasite en phase provenant de la source optique et les moyens d optimiser le débit du système avec des algorithmes d allocation de puissance et modulation. Deuxièmement, nous évaluons l approche IMDD OFDM sous différentes architectures et techniques de partage des ressources du réseau entre les abonnées, à savoir les multiplexages en temps, longueur d onde et fréquence.Despite its success in radio-frequency applications, OFDM has only recently started to draw the attention of the optical community owing principally to the outstanding advancements in electronics and the increasing demands in terms of bit-rates in the last miles of the network. OFDM appears as one possible solution to cost-effectively provide the long-awaited flexibility that lacks on today s somewhat "rigid" passive optical networks (PON). It may also allow their evolution towards higher bit-rates, longer transmission distances and increased number of subscribers per PON tree. Here, we focus on the IMDD approach, which can manage to keep the simplicity and cost-effectiveness at the optical plane by transferring the "hard work" to the digital signal processing domain. We focus this work on two main axes. In the first one, we study the influence of the dispersive IMDD channel frequency response characterized by the interplay between fiber chromatic dispersion and the parasite phase modulation of the light source (chirp) and the ways of optimizing the system s throughput by means of bit and power loading algorithms. Secondly, we evaluate the IMDD OFDM approach under different architectures. Those architectures characterize distinct solutions to share the network ressources between the subscribers, namely time, wavelength and frequency multiplexing.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

TDM-PON PAM Downstream Transmission for 25 Gbit/s and Beyond

The optical access network is currently driving studies on transmissions beyond 10 Gbit/s. This paper reports an analysis of Pulse Amplitude Modulation (PAM), seen as a promising candidate for future Passive Optical Networks (PON). Previous 25 Gbit/s real-time PAM4 results are extrapolated here with simulations to higher bit rates and a higher number of PAM levels. Our main goal is to evaluate the compliancy of PAM with the existing standards and legacy networks as far as fiber length, optical budget class, and wavelength plan are concerned. The simulations enlighten us as to the challenges of multilevel modulation formats, such as noise and jitter, compared to the currently adopted Non-Return-to-Zero (NRZ)