Optical Synthesis of Terahertz and Millimeter-Wave Frequencies with Discrete Mode Diode Lasers

It is shown that optical synthesis of terahertz and millimeter-wave frequencies can be achieved using two-mode and mode-locked discrete mode diode lasers. These edge-emitting devices incorporate a spatially varying refractive index profile which is designed according to the spectral output desired of the laser. We first demonstrate a device which supports two primary modes simultaneously with high spectral purity. In this case sinusoidal modulation of the optical intensity at terahertz frequencies can be obtained. Cross saturation of the material gain in quantum well lasers prevents simultaneous lasing of two modes with spacings in the millimeter-wave region. We show finally that by mode-locking of devices that are designed to support a minimal set of four primary modes, we obtain a sinusoidal modulation of the optical intensity in this frequency region.Comment: 6 page

Point-to-point overlay of a 100Gb/s DP-QPSK channel in LR-PONs for urban and rural areas

The continuing growth in information demand from fixed and mobile end-users, coupled with the need to deliver this content in an economically viable manner, is driving new innovations in access networks. In particular, it is becoming increasingly important to find new ways to enable the coexistence of heterogeneous services types which may require different signal modulation formats over the same fiber infrastructure. For example, the same physical layer can potentially be used to deliver shared 10Gb/s services to residential customers, dedicated point-to-point (P2P) 100Gb/s services to business customers, and wireless fronthaul, in a highly cost-effective manner. In this converged scenario, the performance of phase modulated signals can be heavily affected by nonlinear crosstalk from co-propagating on-off-keying (OOK) channels. In this paper, the overlay of a 100G P2P dual-polarization quadrature phase-shift keying (DP-QPSK) channel in a long-reach passive optical network (LR-PON) in the presence of co-propagating 10Gb/s OOK neighboring channels is studied for two different PON topologies. The first LR-PON topology is particularly suited for densely populated areas while the second is aimed at rural, sparsely populated areas. The experimental results indicate that with an emulated load of 40 channels the urban architecture can support up to 100km span and 512 users, while the rural architecture can support up to 120km span and 1024 users. Finally, a system model is developed to predict the system performance and system margins for configurations different from the experimental setups and to carry out design optimization that could in principle lead to even more efficient and robust schemes

Burst-mode FEC performance for PON upstream channels with EDFA optical transients

The performance of forward error correction (FEC) based on Reed-Solomon coding is analyzed experimentally for a burst-mode upstream channel within a passive optical network (PON) testbed. During this analysis, the upstream FEC performance is impaired by inducing correlated and localized errors within the burst through the injection of optical transients. These transients emulate the optical signal variation associated with the add-and-drop events of wavelength channels within a long-reach optical link based on a chain of erbium doped fiber amplifiers (EDFAs). The robustness of the FEC has been analyzed by measuring the post-FEC bit error rate (BER) as a function of the amplitude of the emulated transients and their delay with respect to the transmitted bursts. A margin of approximately 4dB is demonstrated for the transient amplitude before the FEC degradation. Furthermore, while the post-FEC BER is strongly degraded by the emulated transients, the preFEC BER stays below the FEC threshold, demonstrating the importance of measuring the post-FEC BER in order to correctly characterize the FEC performance in PON upstream channels affected by optical transients

SDN enabled dynamically reconfigurable high capacity optical access architecture for converged services

Dynamically reconfigurable time-division multiplexing (TDM) dense wavelength division multiplexing (DWDM) long-reach passive optical networks (PONs) can support the reduction of nodes and network interfaces by enabling a fully meshed flat optical core. In this paper we demonstrate the flexibility of the TDM-DWDM PON architecture, which can enable the convergence of multiple service types on a single physical layer. Heterogeneous services and modulation formats, i.e. residential 10G PON channels, business 100G dedicated channel and wireless fronthaul, are demonstrated co-existing on the same long reach TDM-DWDM PON system, with up to 100km reach, 512 users and emulated system load of 40 channels, employing amplifier nodes with either erbium doped fiber amplifiers (EDFAs) or semiconductor optical amplifiers (SOAs). For the first time end-to-end software defined networking (SDN) management of the access and core network elements is also implemented and integrated with the PON physical layer in order to demonstrate two service use cases: a fast protection mechanism with end-to-end service restoration in the case of a primary link failure; and dynamic wavelength allocation (DWA) in response to an increased traffic demand

Forward error correction analysis for 10Gb/s burst-mode transmission in TDM-DWDM PONs

The performance limits of 10Gb/s forward error correction for a PON upstream channel are analyzed experimentally by measuring true burst-mode pre- and post-error correction BER, frame loss rate and error location within the burst frame

Débruitage et dématriçage conjoint de vidéo avec des réseaux de neurones convolutifs et récurrents

International audienceDenoising and demosaicing are two critical components of the image/video processing pipeline. While historically these two tasks have mainly been considered separately, current neural network approaches allow to obtain state of-the-art results by treating them jointly. However, most existing research focuses in single image or burst joint denoising and demosaicing (JDD). Although related to burst JDD, video JDD deserves its own treatment. In this work we present an empirical exploration of different design aspects of video joint denoising and demosaicing using neural networks. We compare recurrent and non-recurrent approaches and explore aspects such as type of propagated information in recurrent networks, motion compensation, video stabilization, and network architecture. We found that recurrent networks with motion compensation achieve best results. Our work should serve as a strong baseline for future research in video JDD.Le débruitage et le dématriçage sont deux composantes importantes de la chaîne de traitement des images et des vidéos. Tandis que traditionnellement, ces deux tâches ont largement été appliquées séparément, les approches actuelles basées sur les réseaux de neurones permettent d'atteindre des résultats état de l'art en les traitant conjointement. Cependant, la plupart des recherches en débruitage et dématriçage conjoint (DDC) ne considèrent uniquement que le cas des images ou alors des séries d'images. Bien que lié au DDC de série d'image, le DDC de vidéos mérite son propre traitement. Dans cet article, nous présentons une exploration empirique de différentes conceptions de débruitage et dématriçage conjoint de vidéos en utilisant des réseaux de neurones. Nous y comparons les approches récurrentes et non récurrentes et nous explorons différents aspects tels que le type d'information à propager dans un réseau récurrent, la compensation de mouvement, la stabilization du mouvement des vidéos et l'architecture des réseaux. Nous avons trouvé que les meilleurs résultats sont atteints avec des réseaux récurrents avec compensation du mouvement. Notre travail servira de référence solide pour les futurs travaux en débruitage et dématriçage conjoint de vidéos

Débruitage et dématriçage conjoint de vidéo avec des réseaux de neurones convolutifs et récurrents

International audienceDenoising and demosaicing are two critical components of the image/video processing pipeline. While historically these two tasks have mainly been considered separately, current neural network approaches allow to obtain state of-the-art results by treating them jointly. However, most existing research focuses in single image or burst joint denoising and demosaicing (JDD). Although related to burst JDD, video JDD deserves its own treatment. In this work we present an empirical exploration of different design aspects of video joint denoising and demosaicing using neural networks. We compare recurrent and non-recurrent approaches and explore aspects such as type of propagated information in recurrent networks, motion compensation, video stabilization, and network architecture. We found that recurrent networks with motion compensation achieve best results. Our work should serve as a strong baseline for future research in video JDD.Le débruitage et le dématriçage sont deux composantes importantes de la chaîne de traitement des images et des vidéos. Tandis que traditionnellement, ces deux tâches ont largement été appliquées séparément, les approches actuelles basées sur les réseaux de neurones permettent d'atteindre des résultats état de l'art en les traitant conjointement. Cependant, la plupart des recherches en débruitage et dématriçage conjoint (DDC) ne considèrent uniquement que le cas des images ou alors des séries d'images. Bien que lié au DDC de série d'image, le DDC de vidéos mérite son propre traitement. Dans cet article, nous présentons une exploration empirique de différentes conceptions de débruitage et dématriçage conjoint de vidéos en utilisant des réseaux de neurones. Nous y comparons les approches récurrentes et non récurrentes et nous explorons différents aspects tels que le type d'information à propager dans un réseau récurrent, la compensation de mouvement, la stabilization du mouvement des vidéos et l'architecture des réseaux. Nous avons trouvé que les meilleurs résultats sont atteints avec des réseaux récurrents avec compensation du mouvement. Notre travail servira de référence solide pour les futurs travaux en débruitage et dématriçage conjoint de vidéos