Prof. Li Qian Profile

Prof. Li Qian

Professor at Univ of Toronto

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Author

Publications (18)

Proceedings Article | 2 August 2024 Presentation

Periodically-poled silica fiber as a versatile quantum source

Li Qian, Alexander Greenwood

Proceedings Volume PC13106, PC1310606 (2024) https://doi.org/10.1117/12.3028527

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Proceedings Article | 15 March 2023 Presentation + Paper

Sub-megahertz optical features using a resonator-free twisted Brillouin gain medium

Neel Choksi, Yi Liu, Rojina Ghasemi, Li Qian

Proceedings Volume 12407, 1240703 (2023) https://doi.org/10.1117/12.2656954

KEYWORDS: Polarization, Birefringence, Laser resonators, Cavity resonators, Slow light, Optical resonators, Microwave photonics, Microresonators, Whispering gallery modes, Waveguides

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Proceedings Article | 27 August 2021 Open Access

Fibre-optic quantum entanglement sources

Li Qian

Proceedings Volume 11918, 119180K (2021) https://doi.org/10.1117/12.2611214

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Proceedings Article | 5 March 2021 Presentation

Ultrasound detection aided by bound states in the continuum

Eric Zhu, Li Qian, Ofer Levi

Proceedings Volume 11642, 1164221 (2021) https://doi.org/10.1117/12.2579094

KEYWORDS: Ultrasonography, Sensors, Photonic crystals, Water, Product engineering, Photoelasticity, Optical sensors

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Proceedings Article | 20 April 2020 Presentation

All-optical ultrasound sensing in photonic crystal slabs aided by PMMA (Conference Presentation)

Eric Zhu, Maria Charles, Cory Rewcastle, Raanan Gad, Li Qian, Ofer Levi

Proceedings Volume 11240, 1124012 (2020) https://doi.org/10.1117/12.2545146

KEYWORDS: Ultrasonography, Photonic crystals, Polymethylmethacrylate, Sensors, Ultrasonics, Silicon, Photoelasticity, Water, Biomedical optics, Photoacoustic spectroscopy

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Proceedings Article | 4 March 2019 Presentation

Sensing ultrasound optically with photonic crystal slabs: a tale of two mechanisms (Conference Presentation)

Eric Zhu, Cory Rewcastle, Raanan Gad, Li Qian, Ofer Levi

Proceedings Volume 10878, 108780L (2019) https://doi.org/10.1117/12.2508998

KEYWORDS: Ultrasonography, Photonic crystals, Optical sensing, Crystal optics, Silicon, Water, Nanostructures, Silicon photonics, Sensors, Acoustics

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Proceedings Article | 30 April 2015 Paper

Development of a long-gauge vibration sensor

Peter Kung, Maria Comanici, Qian Li, Yiwei Zhang

Proceedings Volume 9359, 93591F (2015) https://doi.org/10.1117/12.2076068

KEYWORDS: Sensors, Reflectivity, Signal detection, Fiber optics sensors, Sensing systems, Connectors, Structured optical fibers, Light, Signal to noise ratio, Packaging

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Proceedings Article | 17 November 2014 Paper

Development of a long-gauge vibration sensor

Peter Kung, Maria Comanici, Qian Li, Yiwei Zhang

Proceedings Volume 9274, 92741M (2014) https://doi.org/10.1117/12.2072310

KEYWORDS: Sensors, Reflectivity, Signal detection, Fiber optics sensors, Sensing systems, Connectors, Structured optical fibers, Fiber Bragg gratings, Packaging, Corrosion

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Proceedings Article | 10 March 2012 Paper

Chromophore absorbance change quantification in tissue during low-level light therapy

Daniel Huynh, Christine Chung, Li Qian, Lothar Lilge

Proceedings Volume 8211, 821109 (2012) https://doi.org/10.1117/12.909139

KEYWORDS: Tissue optics, Sensors, Absorbance, Electron transport, Chromophores, Low level phototherapy, Light sources, Tissues, Diagnostics, Acquisition tracking and pointing

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Proceedings Article | 21 August 2009 Paper

Sensitization of erbium in silicon oxide by evaporation and thermal oxidation

Hossein Alizadeh, Li Qian, Nazir Kherani, Stefan Zukotynski

Proceedings Volume 7402, 74020P (2009) https://doi.org/10.1117/12.826252

KEYWORDS: Silicon, Erbium, Annealing, Ions, Silica, Oxides, Luminescence, Silicon films, Thermal oxidation, Statistical analysis

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Proceedings Article | 5 September 2008 Paper

Gaussian-modulated coherent state quantum key distribution experiment over 20km telecommunication fiber

Bing Qi, Lei-Lei Huang, Yue-Meng Chi, Li Qian, Hoi-Kwong Lo

Proceedings Volume 7092, 70920J (2008) https://doi.org/10.1117/12.793854

KEYWORDS: Quantum key distribution, Polarization, Homodyne detection, Sensors, Modulators, Signal attenuation, Multiplexing, Laser energy, Telecommunications, Single photon

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Proceedings Article | 3 September 2008 Paper

Measuring chromatic dispersion using single-arm interferometers: from millimeters to kilometers

Li Qian, Bing Qi, Waleed Mohammed, Michael Galle, Fei Ye

Proceedings Volume 7072, 70720D (2008) https://doi.org/10.1117/12.795103

KEYWORDS: Dispersion, Interferometers, Optical fibers, Waveguides, Interferometry, Polarization, Calibration, Tunable lasers, Lead, Nanowires

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Proceedings Article | 11 August 2008 Paper

All-fiber laser beam shaping at 1.0 μm wavelength region in a single-mode fiber

Xijia Gu, Waleed Mohammed, Li Qian, Peter W. E. Smith

Proceedings Volume 7099, 70990L (2008) https://doi.org/10.1117/12.804764

KEYWORDS: Cladding, Beam shaping, Single mode fibers, Fiber lasers, High power fiber lasers, Laser applications, Laser therapeutics, Near field optics, Computer engineering, Medical laser equipment

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Proceedings Article | 25 September 2007 Paper

Improve the efficiency of a practical quantum key distribution system

Bing Qi, Yi Zhao, Xiongfeng Ma, Hoi-Kwong Lo, Li Qian

Proceedings Volume 6710, 671015 (2007) https://doi.org/10.1117/12.730779

KEYWORDS: Sensors, Quantum key distribution, Single photon, Quantum efficiency, Signal detection, Information security, Homodyne detection, Signal attenuation, Phase measurement, Transmittance

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Proceedings Article | 3 June 2007 Open Access

Implementation of three functional devices using erbium-doped fibers: an advanced photonics lab

Wen Zhu, Li Qian, Amr Helmy

Proceedings Volume 9665, 966511 (2007) https://doi.org/10.1117/12.2207348

KEYWORDS: Optical amplifiers, Optical fibers, Fiber lasers, Semiconductor lasers, Optical isolators, Light sources, Signal to noise ratio, Wavelength division multiplexing, Photonics, Erbium

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Proceedings Article | 14 October 2005 Paper

Erbium-Doped Phosphosilicate Fiber Amplifiers: A comparison of configurations for the optimization of noise figure and conversion efficiency

Li Qian, Ryan Bolen

Proceedings Volume 5970, 59702V (2005) https://doi.org/10.1117/12.628682

KEYWORDS: Optical amplifiers, L band, Amplifiers, Erbium, Wavelength division multiplexing, Fiber amplifiers, Absorption, Signal attenuation, Optical fibers, Fusion splicing

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Proceedings Article | 14 October 2005 Paper

Versatile optical pulse shaping using a linearly chirped fibre Bragg grating and an amplitude mask

S. Neata, A. Wong, L. Qian, X. Gu, P. W. E. Smith

Proceedings Volume 5970, 59702H (2005) https://doi.org/10.1117/12.628725

KEYWORDS: Fiber Bragg gratings, Apodization, Pulse shaping, Algorithm development, Switching, Picosecond phenomena, Optical pulse shaping, Ultrafast phenomena, Optimization (mathematics), Modulation

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Optical pulse shaping finds many important applications in the area of ultrafast photonics. For example, in ultrafast all-optical switching, temporal shaping of the control pulses can be used to create a wide flat-top switching window with sharp rise and fall times. Such switching windows are more jitter-tolerant than simple Gaussian windows, and can therefore achieve a lower bit-error rate. Previously reported pulse shaping methods using linearly chirped Fibre Bragg Gratings (FBGs) take advantage of the direct correspondence between the spatial distribution of the grating periods and the temporal distribution of the spectral contents of the grating impulse response (space-to-frequency-to-time mapping). However, they have two major drawbacks: first, they are only valid for high-dispersion gratings, and therefore are unsuitable for producing short pulses; second, due to the inherent impulse response assumption, the power conversion efficiency is very low since the grating bandwidth needs to be much smaller than that of the input pulse. The numerical conversion efficiency demonstrated for this method is about a few percent. We report a versatile technique for temporal pulse shaping using a simple linearly chirped FBG and an amplitude mask. Unlike previous pulse shaping methods, ours is also applicable for low-dispersion gratings with bandwidths comparable to that of the input pulse (i.e., taking into account of finite input pulse duration). The chirped grating is used to stretch the incoming pulses to the desirable temporal width, while the amplitude mask modifies the shape of the pulses. We developed a novel optimization algorithm to obtain an amplitude mask that significantly increases the conversion efficiency. Pulse shaping using linearly chirped FBGs in the low dispersion regime is simulated using two methods. For weak gratings, the direct relationship between the spatial grating profile and the grating impulse response was used in tandem with a forward-correction deconvolution algorithm to solve for the optimum amplitude mask. For strong gratings, an optimization algorithm based on the partial validity of space-time mapping, as well as the causal relationship between the reflected temporal response and the grating apodization profile was used to design the amplitude mask. We experimentally demonstrated the conversion of 1-ps transform-limited Gaussian pulses to 10-ps pulses with a target shape at a high conversion efficiency of ~20% (measured) using a 1.5-mm-long grating. The spectral width of the pulses is 3.5 nm, centered at 1.55μm. As the reflected pulse shape is controlled by the shape of the amplitude mask, our method can be easily adapted to produce any arbitrary temporal pulse shape by designing an appropriate amplitude mask. To our knowledge, this is the first demonstration of this technique of arbitrary pulse shaping using the combination of a linearly chirped fiber grating and an amplitude mask in the low-dispersion regime.

Proceedings Article | 20 December 2004 Paper

Low-cost technique for gain and noise figure measurement of erbium-doped fiber amplifiers using a broadband source and filter tuning

Sanjay Gupta, Li Qian

Proceedings Volume 5577, (2004) https://doi.org/10.1117/12.566974

KEYWORDS: Optical amplifiers, Optical filters, Fiber amplifiers, Superluminescent sources, Tunable filters, Bragg cells, Semiconductor optical amplifiers, Solids, Amplifiers, Modulation

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Showing 5 of 18 publications

Conference Committee Involvement (1)

Optical Communication Systems and Networks

12 September 2005 | Toronto, Canada

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