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Personne :
Rusch, Leslie

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Rusch

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Leslie

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Université Laval. Département de génie électrique et de génie informatique

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ncf11860324

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Voici les éléments 1 - 10 sur 61
  • PublicationAccès libre
    Single-Sideband OFDM Transmission via a Silicon Microring IQ Modulator
    (Institute of Electrical and Electronics Engineers, 2018-12-31) Xu, Yelong; Shi, Wei; Rusch, Leslie; Lyu, Mingyang
    We experimentally demonstrate the generation of a single-sideband orthogonal frequency division multiplexed (OFDM) signal using an on-chip silicon photonics microring-based IQ modulator. Over 18-dB sideband suppression ratio is achieved for the wideband OFDM: 15.7-GHz data band and 2.7-GHz guard band. The 31.4-Gb/s signal was transmitted over 20 km of standard single-mode fiber with a bit error rate below the forward error correction threshold. While single-sideband continuous-wave signals have been produced with such hardware, this is the first demonstration of stable data transmission on the single sideband carrier.
  • PublicationAccès libre
    Silicon photonic subsystem for broadband and RoF detection while enabling carrier reuse
    (Optical Society of America, 2020-05-01) Lyu, Mingyang; Shi, Wei; Rusch, Leslie
    We experimentally validate a silicon photonic subsystem designed for passive optical networks with carrier reuse. The subsystem is intended for future wavelength division multiplexed (WDM) PONs. It enables radio-over-fiber signals to cohabit an assigned wavelength slot without perturbing the PON signal, while conserving carrier power for the uplink. A microring modulator remodulates the residual carrier for the RoF uplink. We successfully detected the dropped 8 GHz broadband signal and five 125 MHz radio-over-fiber signals. Two 125 MHz radio over fiber signals are remodulated onto the carrier. The uplink signal shows good performance, validating the residual downlink signals have been well rejected by the microring filters. The subsystem conserves a clean carrier for remodulation with good signal-to-carrier ratio.
  • PublicationAccès libre
    Radially anisotropic ring-core optical fiber : towards vector-vortex guided transmission using the full modal space
    (Optical Society of America, 2021-04-06) Sharma, Manish; LaRochelle, Sophie; Vigneswaran, Dhasarathan; Ung, Bora; Rusch, Leslie
    The radially anisotropic ring-core fiber with cylindrical birefringence is theoretically and numerically investigated as a novel platform for the transmission of vector-vortex beams with unique modal properties. First, we elucidate the parametric conditions where such fiber enables modal substitution in which either the donut-shaped azimuthal TE01 or radial TM01 mode replaces the normal Gaussian-like HE11 mode as the fundamental mode of the waveguide. We also demonstrate that it is possible to significantly engineer the waveguiding properties of the fiber via the addition of small radial birefringence (~10−4 ) so as to make the (hitherto non-degenerate) TE0m and TM0m modes fully degenerate. The latter property is used to create stable vortex modes of high purity (>99%) with the newly degenerate modal pair – a feat not possible with standard few-mode fibers – all without affecting the co-propagating hybrid HE/EH modes that remain available as an independent basis set to produce vortex beams of similarly high purity. These new insights are relevant to the topical fields of mode-division multiplexing (MDM), structured light, fiber modelling and fabrication. With respect to MDM applications, the newly available vortex modes created with the degenerate TE/TM basis set can now be concurrently used with the more common vortex modes created via the HE/EH modal basis set.
  • PublicationAccès libre
    Demonstration and evaluation of an optimized RFS comb for terabit flexible optical networks
    (Optical Society of America, 2017-09-20) Lin, Jiachuan; LaRochelle, Sophie; Lyu, Mingyang; Wang, Lixian; Pai, Amruta; Rusch, Leslie; Zhang, Xiaoguang
    We experimentally demonstrate and evaluate an optimization strategy of a recirculating frequency shifting (RFS) optical comb for terabit flexible optical networks. We achieve an increased optical signal-to-noise ratio (OSNR) with good stability (no system outage) by reducing erbium-doped-fiber amplifier gain in the shifting loop and deploying an in-loop noise suppression filter. We demonstrate that this source can support 20×200  Gb/s dual polarization Nyquist-16QAM transmission. With optimization, the RFS comb has greater and more uniform OSNR per channel. Flexible optical networks with software-defined networking are particularly suited to this enhanced RFS due to 1) programmable frequency spacing, 2) dense, stable spacing enabling very high spectral efficiency, 3) uniform performance across channels, and 4) sufficient OSNR for high-order modulation. The RFS can be used in short links when using low overhead forward error correction (FEC). Distances as great as 1150 km are achieved when using a 20% FEC overhead. Long-distance tests at 4 Tb/s result in a post-FEC net rate of 3.3 Tb/s and 6.3 bit/s/Hz of spectral efficiency.
  • PublicationAccès libre
    Mitigating pattern dependent nonlinearity in SiP IQ-modulators via iterative learning control predistortion
    (Optical Society of America, 2018-10-15) Lin, Jiachuan; Zhalehpour, Sasan; Sepehrian, Hassan; Shi, Wei; Rusch, Leslie
    Silicon based Mach Zehnder modulators, unlike lithium niobate, suffer from nonlinear pattern-dependent behavior beyond simple intersymbol interference. We experimentally demonstrate a novel predistortion method based on the iterative learning control (ILC) technique to address this issue using quasi-real-time adaptation with hardware-in-the-loop. We compare bit error rate performance to that of linear solutions at several M-QAM modulation levels and baud rates. We demonstrate 256QAM at 20 Gbaud which linear compensation alone cannot achieve. For 40 Gbaud 128QAM, we improve power sensitivity by 4.4 dB. We combine optical compensation with ILC to improve power sensitivity by ∼ 5 dB for 60 Gbaud 32QAM.
  • PublicationAccès libre
    Analysis of modal coupling due to birefringence and ellipticity in strongly guiding ring-core OAM fibers
    (Optical Society of America, 2019-03-18) Guerra, Gianluca; Rusch, Leslie; Lonardi, Matteo; Galtarossa, Andrea; Bononi, Alberto; Palmieri, Luca
    After briefly recalling the issue of OAM mode purity in strongly-guiding ring-core fibers, this paper provides a methodology to calculate the coupling strength between OAM mode groups due to fiber perturbations. The cases of stress birefringence and core ellipticity are theoretically and numerically investigated. It is found that both perturbations produce the same coupling pattern among mode groups, although with different intensities. The consequence is that birefringence causes the highest modal crosstalk because it strongly couples groups with a lower propagation-constant mismatch. The power coupling to parasitic TE and TM modes is also quantified for both perturbations and is found to be non-negligible. Approximate modal crosstalk formulas valid for weakly-guiding multi-core fibers, but whose parameters are adapted to the present case of strongly guiding OAM fibers, are found to provide a reasonable fit to numerical results. Finally, the effect that modal coupling has on OAM transmission is assessed in terms of SNR penalty.
  • PublicationAccès libre
    Mode loss measurement in few-mode fibers with a microwave interferometric technique
    (IEEE, 2018-02-19) Corsi, Alessandro; LaRochelle, Sophie; Wang, Lixian; Rusch, Leslie
    We measure the mode dependent loss (MDL) of a few-mode fiber (FMF) using an improved microwave interferometric technique. A frequency-swept microwave signal modulates a filtered optical incoherent source that is injected into the FMF under test. During propagation, the microwave signal carried by the various modes experiences different losses and delays before interfering at the photodetector. The fiber MDL, between mode groups, is computed from the interference pattern by measuring two different fiber lengths under the same excitation condition. This technique relies on the dominant excitation of the fundamental mode and therefore can measure high values of MDL.
  • PublicationAccès libre
    Highly-elliptical-core fiber with stress-induced birefringence for mode multiplexing
    (Optical Society of America, 2020-05-13) Chang, Junho; Corsi, Alessandro; LaRochelle, Sophie; Wang, Lixian; Wang, Ruohui; Rusch, Leslie
    We report the polarization-maintaining properties of a highly elliptical core fiber surrounded by a trench that was designed to optimize the modal effective indices and bending loss for a total of five spatial modes (10 channels). In addition to the asymmetric core structure, the birefringence of the fiber is increased by the thermal stress introduced during the fabrication. The results show a modal birefringence larger than 10-4 for all guided spatial modes. The mode stability to bending is evaluated by selectively exciting/detecting each spatial mode while perturbing the fiber. This few-mode polarization-maintaining fiber is of interest for multiple-input multiple-output (MIMO)-free mode division multiplexing transmission systems.
  • PublicationAccès libre
    Perfect vortex modes for nondestructive characterization of mode dependent loss in ring core fibers
    (New York, N.Y. : Institute of Electrical and Electronics Engineers, 2022-08-02) Banawan, Mai; Mishra, Satyendra K.; Messaddeq, Younès; LaRochelle, Sophie; Rusch, Leslie
    Ring core fibers (RCF) enable high-performance modal multiplexing with low crosstalk and can support orbital angular momentum (OAM) modes. RCFs are challenging to characterize due to the lack of commercial multiplexers, especially for high OAM orders. For fibers supporting large numbers of modes, typical cutback techniques for characterization are extremely wasteful of fiber, especially as one cutback is required for each mode. We show the differential modal loss across modes 3 to 10 was significantly underestimated using an OTDR when exciting modes individually or when exciting all modes indiscriminately. We exploit perfect vortex beams to achieve reliable and nondestructive characterization of mode-dependent loss (MDL) for OAM modes. Perfect vortex beams allow us to maximize the coupling efficiency at each mode launch, increasing the accuracy of MDL estimate. We fabricated fiber with a refractive index difference between the ring core and the cladding of a 5.1×10⁻². For this fiber, mode orders 3 to 10 are the most suitable for data transmission and were the focus of our work (the fiber support up to OAM order 13). Such a high index difference can lead to MDL. We demonstrate that the modal loss spans from 2.14 to 4.38 dB/km for orders 3 to 10.
  • PublicationAccès libre
    The impact of modal interactions on receiver complexity in OAM fibers
    (Institute of Electrical and Electronics Engineers,, 2017-09-11) Mirzaei Nejad, Reza; Lin, Jiachuan; LaRochelle, Sophie; Wang, Lixian; Rusch, Leslie
    We experimentally study the modal interactions in mode division multiplexing (MDM) links supporting orbital angular momentum (OAM) modes of order zero and one. We use time of flight and channel impulse response measurements to characterize our OAM-MDM link and quantify modal impairments. We examine two OAM fibers with different index profiles and differential mode group delays (DMGD) between supported vector modes. Data transmission experiments probe the impact of modal impairments on digital signal processing complexity and achievable bit error rate for OAM-MDM link. We discuss in particular memory depth requirements for equalizers in separate mode detection schemes, and how memory depth varies with DMGD metrics as well as crosstalk level.