Personne :
Shi, Wei

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Adresse électronique
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Université Laval. Département génie électrique et génie informatique
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Voici les éléments 1 - 10 sur 57
  • Publication
    Accès libre
    Time-domain large-signal modeling of traveling-wave modulators on SOI
    (Institute of Electrical and Electronics Engineers, 2016-06-01) Park, Chul Soo; Bahrami, Hadi; Sepehrian, Hassan; Shi, Wei; Rusch, Leslie
    Silicon photonic modulators have strong nonlinear behavior in phase modulation and frequency response, which needs to be carefully addressed when they are used in high-capacity transmission systems. We demonstrate a comprehensive model for depletion-mode Mach-Zehnder modulators (MZMs) on silicon-on-insulator, which provides a bridge between device design and system performance optimization. Our methodology involves physical models of p-n-junction phase-shifters and traveling-wave electrodes, as well as circuit models for the dynamic microwave-light interactions and time-domain analysis. Critical aspects in the transmission line design for high-frequency operation are numerically studied for a case of p-n-junction loaded coplanar-strip electrode. The dynamic interaction between light and microwave is simulated using a distributed circuit model solved by the finite-difference time-domain method, allowing for accurate prediction of both small-signal and large-signal responses. The validity of the model is confirmed by the comparison with experimental results for a series push-pull MZM with a 6 mm phase shifter. The simulation shows excellent agreement with experiment for high-speed operation up to 46 Gb/s. We show that this time-domain model can well predict the impact of the nonlinear behavior on the large-signal response, in contrast to the poor prediction from linear models in the frequency domain.
  • Publication
    Accès libre
    Chip-scale, full-Stokes polarimeter
    (Optical Society of America, 2019-02-18) Lin, Zhongjin; Shi, Wei; Chen, Yuxuan; Rusch, Leslie
    The polarization of light conveys unique information that can be exploited by crucial applications. The bulky and costly discrete optical components used in conventional polarimeters limit their broad adoption. A compact, low-cost polarimeter would bring this functionality into a myriad of new scenarios and revolutionize its exploitation. Here we present a high-performance, full-Stokes polarimeter on a silicon chip. A surface polarization splitter and on-chip optical interferometer circuit produce the complete analysis matrix of an optimally conditioned polarimeter. A matrix analysis on measurement errors is also performed. This solid-state polarimeter is a system-on-a-chip with exceptional compactness, stability, and speed that could be used singly or in integrated arrays. Large arrays can increase the speed and resolution of full-Stokes imaging; therefore, our design provides a scalable polarimeter solution.
  • Publication
    Accès libre
    Silicon photonic modulator using mode conversion with asymmetric sidewall bragg gratings
    (IEEE, 2018-10-04) Jafari, Omid; LaRochelle, Sophie; Shi, Wei
    An asymmetric sidewall grating allows to operate a Bragg modulator in reflection without circulator and with less than 1.5 dB on-chip loss. An asymmetric Y-branch directs the incident TE0 mode to the grating, while the reflected TE1 mode is guided to the drop port.
  • Publication
    Accès libre
    Widely tunable silicon Raman laser
    (Optical Society of America, 2021-05-05) Ahmadi, Mohammad; LaRochelle, Sophie; Shi, Wei
    Stimulated Raman scattering is an effective means of wavelength conversion and can largely extend the operating spectral range of an optical source. We demonstrate a high-performance tunable Raman laser on a sub-micrometer-thick silicon on insulator wafer using a standard foundry process. The key feature to this laser is the use of a tunable coupling mechanism to adjust both pump and signal coupling coefficients in the ring cavity, allowing demonstration of laser emission over a large wavelength tuning range of 83 nm. This Raman laser demonstrates efficient (slope of up to 26% and a maximum pump-to-signal power conversion efficiency of 10%) on-chip nonlinear wavelength conversion. Our results indicate great promise for substantially increasing the optical spectral resources available on a silicon chip.
  • Publication
    Accès libre
    Hybrid silicon-fiber funable multi-wavelength laser with switchable frequency spacing
    (IEEE, 2019-09-02) Jean, Philippe; Vallée, Jean-Michel; Shi, Wei
    Agile optical systems and elastic optical networks demand for flexible, high-performance laser sources. We demonstrate a hybrid silicon-fiber laser that can be largely tuned in wavelength, switched in frequency spacing and easily switched between multi- and single-wavelength operations. Single-mode laser with a fiber-coupled output power of 6 to 8 dBm was measured across the spectral range of 1545 to 1560 nm. No significant sign of power limitation from nonlinear absorption or free carrier generation in silicon was found. It is thus expected that a higher output can be obtained by improving the gain saturation performances as well as the fiber-to-chip coupling efficiency. For multiwavelength operation, we have achieved a frequency spacing switchable between 56 GHz, 75 GHz, and 225 GHz. For both the multi- and single-wavelength operations, a linewidth of less than 20 kHz was measured. All the tuning mechanisms have been realized on the silicon chip, providing a scalable solution for tunable fiber lasers with minimized cost and integration complexity.
  • Publication
    Accès 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.
  • Publication
    Accès libre
    Ultrafast pulse-amplitude modulation with a femtojoule silicon photonic modulator
    (Optical Society of America, 2016-06-09) Dubé-Demers, Raphaël; LaRochelle, Sophie; Shi, Wei
    Ultrahigh-speed optical interconnects are essential to future cloud computing. Further increase in optical transmission speed has been hindered by power consumption and limited bandwidth resources, for which integrated optical transceivers using advanced modulation formats, such as pulse-amplitude modulation (PAM), are a promising solution. We report 80 Gb/s PAM operation of a silicon microring modulator (MRM) with an ultralow power consumption below 7 fJ/bit. We also report the first demonstration of PAM-8 modulation of MRMs in the Gb/s order, achieving error-free capability at 45 Gb/s, using 1 fJ/bit. To the best of our knowledge, these results feature the lowest power consumption, per transmitted bit, ever demonstrated at such high data rates. We further demonstrate PAM data transmission up to 64 Gb/s over 5 km. Simultaneous achievement of ultrafast modulation and ultralow power consumption is a critical step toward next-generation optical interconnects.
  • Publication
    Accès libre
    On-chip Fourier transform spectrometers by dual-polarized detection
    (Optical Society of America, 2019-06-01) Wang, Huijie; Lin, Zhongjin; Li, Qifeng; Shi, Wei
    Chip-scale Fourier transform spectrometers (FTSs) have recently emerged for inexpensive, high-resolution spectroscopic applications. In particular, spatial-heterodyne FTSs (SH-FTSs) have drawn considerable attention with a simple and stable configuration based on an array of Mach–Zehnder interferometers (MZIs) with linearly increased optical path differences. There is a significant trade-off between spectral performance and the MZI number. In this work, we propose a dual-polarized SH-FTS, detecting both fundamental transverse electric and transverse magnetic modes, on a silicon photonic chip. Our experimental results show that, compared to the conventional single-polarized design, the MZI number of the dual-polarized SH-FTS can be nearly halved for a smaller footprint with little compromise of spectral performance.
  • Publication
    Accès 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.
  • Publication
    Accès libre
    High-efficiency silicon photonic modulator using coupled Bragg grating resonators
    (Institute of Electrical and Electronics Engineers, 2019-02-05) Jafari, Omid; Sepehrian, Hassan; LaRochelle, Sophie; Shi, Wei
    We propose a novel design of a silicon photonic modulator that has a high modulation efficiency and that is tolerant to temperature variations. A series of phase-shifted Bragg gratings are placed in each arm of a Mach-Zehnder interferometer in order to provide enhanced phase modulation. The slow light effect in these ultra-compact coupled resonators improves phase modulation efficiency compared to conventional silicon phase shifters. These Bragg grating cavities are designed such that the optical bandwidth is increased compared to other coupled resonators such as micro-rings. This improved bandwidth reduces the temperature sensitivity of the devices. We present in detail how to optimize these modulators considering properties such as modulation efficiency (Vπ×L), optical modulation amplitude (OMA), and optical bandwidth (𝛥λBW); the latter property determining the operating temperature range (𝛥T). As examples, we present two designs that meet different target specifications for short-reach or long-haul applications. We further provide a model, based on coupled mode theory, to investigate the dynamic response of the proposed modulators. A large signal analysis is performed using finite difference time domain (FDTD) in order to simulate on/off keying (OOK) modulation and eye diagrams up to 110 Gb/s.