Personne : LaRochelle, Sophie
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LaRochelle
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Sophie
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Université Laval. Département de génie électrique et de génie informatique
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ncf10263799
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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, WeiWe 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.Publication Accès libre Mach-Zehnder silicon photonic modulator assisted by phase-shifted Bragg gratings(Institute of Electrical and Electronics Engineers, 2020-03-05) Jafari, Omid; LaRochelle, Sophie; Shi, WeiWe experimentally demonstrate a silicon photonic Mach-Zehnder modulator (MZM) assisted by phase-shifted Bragg gratings. Coupled resonators are inserted in the Bragg grating structure to significantly enhance the phase modulation efficiency, while maintaining a wide optical bandwidth compared to other resonator-based modulators. Fabricated using a CMOS-compatible foundry process, the device achieved a small-signal Vπ× L of 0.18 V.cm, which is seven times lower than a conventional silicon MZM fabricated with the same process. The device has a compact footprint, with a length of only 162 μm , and shows a modulation bandwidth of 28 GHz at a reverse bias of 1 V. Non-return-to-zero modulation is demonstrated at 30 Gb/s with a bit-error-rate (BER) below the 7%-overhead forward error correction (FEC) threshold over a bandwidth of 3.5 nm. This bandwidth should translate into an operating temperature range greater than 40 0 C.Publication Accès libre Silicon photonic modulator loaded by NPN junctions(Institute of electrical and electronics engineers, 2020-08-17) Jafari, Omid; LaRochelle, Sophie; Shi, WeiWe experimentally demonstrate an asymmetric Bragg grating modulator with a phase shifter length of 240 μm, loaded by p-n junctions. The mode conversion by the asymmetric sidewall grating allows us to operate a Bragg modulator in reflection without a circulator. Simulation results show that there is room for improving the modulator efficiency and footprint by exploiting NPN junctions instead of p-n junctions.Publication Accès libre Silicon photonic modulator based on coupled Bragg grating resonators used as phase shifters(Optical Society of America, 2018-03-11) Jafari, Omid; Sepehrian, Hassan; LaRochelle, Sophie; Shi, WeiBragg gratings with phase-shifts are inserted in a Mach-Zehnder modulator to enhance phase modulation, reduce device length and improve efficiency (Vπ×L=0.28 Vcm). Simulations show 3 nm optical bandwidth corresponding to 50 K operating temperature range.Publication Accès libre Widely bandwidth-tunable silicon filter with an unlimited free-spectral range(Optical Society of America, 2015-11-17) Bahrami, Hadi; Jean, Philippe; St-Yves, Jonathan; LaRochelle, Sophie; Shi, WeiNext-generation high-capacity optical networks require flexible allocation of spectrum resources, for which low-cost optical filters with an ultra-wide bandwidth tunability beyond 100 GHz are desired. We demonstrate an integrated band-pass filter with the bandwidth continuously tuned across 670 GHz (117–788 GHz) which, to the best of our knowledge, is the widest tuning span ever demonstrated on a silicon chip. The filter also features simultaneous wavelength tuning and an unlimited free spectral range. We measured an out-of-band contrast of up to 55 dB, low in-band ripples of less than 0.3 dB, and in-band group delay variation of less than 8 ps. This result was achieved using cascaded Bragg-grating-assisted contra-directional couplers and micro-heaters on the 220 nm silicon-on-insulator platform with a very compact footprint of less than 7000 μm2. Another design with the bandwidth continuously tunable from 50 GHz to 1 THz is also presented.Publication Accès libre Large area Bragg grating for pump recycling in cladding-pumped multicore erbium-doped fiber amplifiers(Optical Society of America, 2022-05-09) Talbot, Lauris; Matte-Breton, Charles; LaRochelle, Sophie; Messaddeq, Younès; Bernier, MartinWe demonstrate for the first time that a Bragg grating can be written over a large area inside the cladding of a multicore erbium-doped fiber amplifier to increase the power conversion efficiency (PCE) by recycling the output pump power. Our results indicate that a Bragg grating covering ~25% of the cladding area allows to recycle 19% of the output pump power which leads to a relative increase of the PCE by 16% for an input pump power of 10.6 W in the specific case of an eight-core erbium-doped fiber with a length of 20.3 m and one core loaded with an input signal power of 1.5 dBm.Publication Restreint DAC-less PAM-4 slow-light silicon photonic modulator providing high efficiency and stability(Institute of Electrical and Electronics Engineers, 2021-05-25) Jafari, Omid; Zhalehpour, Sasan; LaRochelle, Sophie; Shi, WeiWe report a slow-light silicon modulator that enables high-speed PAM operation without using an electrical digital-to-analogue converter (DAC). Bragg grating resonators, integrated into each arm of a Mach-Zehnder modulator, enhance the phase modulation through the slow light effect. The optical 4-level PAM signal is generated by driving directly the segmented phase shifter design with two binary signals. This modulator presents an ultra-compact footprint (LSL-MZM = 570 m), low energy consumption (73 fJ/bit), large electro-optic bandwidth (> 40 GHz). Up to 90 Gb/s is achieved over an nm-range spectral operation bandwidth (= 2 nm). Compared to other low-energy resonator-based modulators, such as micro-rings, this operating bandwidth confers higher stability with a potential operating temperature range of T = 50 C. We further examine the robustness of the proposed design to fabrication variations by measurements of spectral properties across the wafer. This modulator is of particular interest for applications, such as short-range data communications that require multiple compact and energy-efficient modulators on a single chipPublication Accès libre Silicon photonic modulator using mode conversion with asymmetric sidewall bragg gratings(IEEE, 2018-10-04) Jafari, Omid; LaRochelle, Sophie; Shi, WeiAn 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 Restreint Mode-conversion-based silicon photonic modulator using asymmetric Bragg grating and Y-branch(2019-09-22) Lin, Jiachuan; Jafari, Omid; LaRochelle, Sophie; Shi, WeiWe experimentally demonstrate a Bragg-grating-based modulator operating in reflection with low loss and without a circulator by using mode conversion and an asymmetric Y-branch. With a compact footprint of 240μm, we demonstrate OOK up to 30 Gbit/s with an estimated switching energy of 150 fJ/bit.Publication Accès libre Subwavelength-grating contra-directional couplers for large stopband filters(Optical Society of America, 2018-02-14) Jafari, Omid; Charron, Dominique; St-Yves, Jonathan; LaRochelle, Sophie; Shi, WeiManipulating the coupling coefficient at subwavelength scales provides an additional degree of freedom in designing integrated Bragg gratings. We demonstrate asymmetric contradirectional couplers (contra-DCs) using sidewall-corrugated subwavelength grating (SWG) waveguides for broadband add–drop Bragg filters. We show that a SWG can effectively increase the overlap of coupled modes and thus the photonic band gap. The measured spectra show good agreement with the prediction of photonic band structure simulations. A record bandwidth of 4.07 THz (33.4 nm) has been achieved experimentally. A four-port Bragg resonating filter made of a phase-shifted Bragg grating SWG contra-DC is also demonstrated for narrow-band (near 100 GHz) filtering. All these devices are achieved on the 220-nm silicon-on-insulator platform with a compact length of less than 150 μm. These large stopband filters may find important applications such as band splitting, reconfigurable channel band switching, bandwidth-tunable filtering, and dispersion engineering.