Prof. J. Stewart Aitchison Profile

Prof. J. Stewart Aitchison

Professor at Univ of Toronto

SPIE Involvement:

Author

Publications (31)

Proceedings Article | 13 March 2024 Presentation + Paper

Fluorescent imaging cytometer for the detection of inflammation biomarkers using temporally multiplexed illumination

Ziyin Wei, Xilong Yuan, Yali Gao, Lu Chen, Mianjun Wang, Nathan Ng, Jiahua Dou, Stewart Aitchison

Proceedings Volume 12822, 1282203 (2024) https://doi.org/10.1117/12.3002649

KEYWORDS: Multiplexing, Light sources and illumination, Light emitting diodes, Point-of-care devices, Quantum detection, Inflammation, Fluorescence imaging, Cameras, Quantum dots, Quantum channels

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Proceedings Article | 9 March 2020 Presentation

Augmented low-index waveguides (Conference Presentation)

J. Stewart Aitchison, Mo Mojahedi, Xiao Sun

Proceedings Volume 11284, 112841D (2020) https://doi.org/10.1117/12.2555087

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Proceedings Article | 14 March 2018 Presentation

Entangled photon generation in AlGaAs waveguides (Conference Presentation)

Stewart Aitchison

Proceedings Volume 10540, 1054029 (2018) https://doi.org/10.1117/12.2289449

KEYWORDS: Nonlinear optics, Waveguides, Group III-V semiconductors, Absorption, Integrated optics, Photodiodes, Modulators, Optical components, Four wave mixing, Solar cells

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Proceedings Article | 19 April 2017 Paper

Femtosecond laser direct-write of optofluidics in polymer-coated optical fiber

Kevin A. Joseph, Moez Haque, Stephen Ho, J. Stewart Aitchison, Peter Herman

Proceedings Volume 10094, 1009414 (2017) https://doi.org/10.1117/12.2256996

KEYWORDS: Polymers, Optical fibers, Microfluidics, Waveguides, Femtosecond phenomena, Cladding, Fiber lasers, Fiber Bragg gratings, Structured optical fibers, Silica

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Proceedings Article | 3 May 2016 Presentation

Portable point-of-care blood analysis system for global health (Conference Presentation)

James Dou, James Stewart Aitchison, Lu Chen, Rakesh Nayyar

Proceedings Volume 9699, 96990M (2016) https://doi.org/10.1117/12.2212666

KEYWORDS: Point-of-care devices, Blood, Microfluidics, Image analysis, Algorithm development, Microfluidic imaging, Detection and tracking algorithms, Detector development, Target detection, Particles

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Proceedings Article | 4 March 2016 Presentation + Paper

Fluorescent detection of C-reactive protein using polyamide beads

Shreesha Jagadeesh, Lu Chen, Stewart Aitchison

Proceedings Volume 9715, 971505 (2016) https://doi.org/10.1117/12.2211373

KEYWORDS: Proteins, Plasma, Blood, Point-of-care devices, Bacteria, Magnetism, Microfluidic imaging, Microfluidics, Microscopes, Adsorption, Medicine, Coating, Statistical analysis

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Proceedings Article | 5 September 2014 Paper

Integrated optical hydrogen and temperature sensor on silicon-on-insulator platform

M. Alam, N. Carriere, Mo. Mojahedi, J. Aitchison

Proceedings Volume 9202, 920207 (2014) https://doi.org/10.1117/12.2061498

KEYWORDS: Sensors, Hydrogen, Palladium, Temperature sensors, Silicon, Resonators, Integrated optics, Waveguides, Aerospace engineering, Temperature metrology

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Proceedings Article | 7 December 2013 Paper

Micro-structured surfaces for algal biofilm growth

Suthamathy Sathananthan, Scott Genin, J. Stewart Aitchison, D. Grant Allen

Proceedings Volume 8923, 892350 (2013) https://doi.org/10.1117/12.2033794

KEYWORDS: Polymethylmethacrylate, Natural surfaces, Semiconducting wafers, Photomasks, Optical lithography, Silicon, Electron beam lithography, Oxides, Tissue engineering, Lithography

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Proceedings Article | 15 February 2012 Paper

Femtosecond laser writing of polarization devices for optical circuits in glass

Luís A. Fernandes, Jason Grenier, Peter Herman, J. Stewart Aitchison, Paulo V. Marques

Proceedings Volume 8247, 82470M (2012) https://doi.org/10.1117/12.907517

KEYWORDS: Polarization, Waveguides, Birefringence, Femtosecond phenomena, Wave plates, Beam splitters, Polarizers, Pulsed laser operation, Glasses, Silica

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Proceedings Article | 3 February 2012 Paper

A microfluidic based optical particle detection method

James Dou, Lu Chen, Rakesh Nayyar, Stewart Aitchison

Proceedings Volume 8229, 82290B (2012) https://doi.org/10.1117/12.905049

KEYWORDS: Microfluidics, Particles, Capillaries, Sensors, Blood, Flow cytometry, Luminescence, Statistical analysis, Microfluidic imaging, Imaging systems

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Proceedings Article | 2 February 2012 Paper

Bragg-grating air-slot optical waveguide for label-free sensing

A. Jugessur, M. Yagnyukova, J. Dou, J. Aitchison

Proceedings Volume 8231, 82310N (2012) https://doi.org/10.1117/12.908562

KEYWORDS: Waveguides, Finite-difference time-domain method, Refraction, Optical sensors, Silicon, Electron beam lithography, Reactive ion etching, Fiber Bragg gratings, 3D modeling, Medicine

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Proceedings Article | 12 February 2011 Paper

Silicon-on-insulator nanopillar-array optical sensor

Tao Xu, Michelle Xu, Ning Zhu, Priyadarshini Kumari, Lech Wosinski, Stewart Aitchison, Harry Ruda

Proceedings Volume 7908, 79080O (2011) https://doi.org/10.1117/12.874099

KEYWORDS: Optical microcavities, Refractive index, Coating, Silicon, Sensors, Optical sensors, Finite-difference time-domain method, Silica, Semiconducting wafers, Waveguides

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Proceedings Article | 23 September 2010 Paper

Performance and limitations of quasi-phase matching semiconductor waveguides with picosecond pulses

Sean Wagner, S. Chaitanya Kumar, Omid Kokabee, Barry Holmes, Usman Younis, Majid Ebrahim Zadeh, David Hutchings, Amr Helmy, J. Stewart Aitchison

Proceedings Volume 7750, 77501K (2010) https://doi.org/10.1117/12.873093

KEYWORDS: Waveguides, Second-harmonic generation, Picosecond phenomena, Superlattices, Fiber lasers, Semiconductors, Optical parametric oscillators, Frequency conversion, Phase matching

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Quasi-phase matched (QPM) second-order nonlinear optical processes in compound semiconductors are attractive for frequency conversion because of their large nonlinear susceptibilities and their mature fabrication processes that permit monolithic integration with pump lasers and other optical elements. Using quantum well intermixing (QWI), we have fabricated domain-disordered QPM (DD-QPM) waveguides in GaAs/AlGaAs superlattices and have previously demonstrated continuous-wave (CW) Type-I second-harmonic generation (SHG) and pulsed Type-II SHG. CW experiments were complicated by Fabry-Perot resonances and thermal bistability. Experiments using a 2-ps pulsed system were affected by third-order nonlinear effects, group-velocity mismatch (GVM), and poor spectral overlap with the conversion bandwidth. A better evaluation of the conversion efficiency may, however, be determined by using longer pulses in order to avoid these complications. By this, the effective CW conversion efficiency and χ⁽²⁾ modulation can be ascertained. In this paper, we demonstrate SHG in DD-QPM waveguides with reduced parasitic effects by using 20 ps pulses. The waveguide structure consisted of a core layer of GaAs/Al_0.85Ga0.15As superlattice into which QPM gratings with a period of 3.8 μm were formed using QWI by As²⁺ ion implantation. For a Type-I phase matching wavelength of 1583.4 nm, average second-harmonic (SH) powers produced were as high as 2.5 μW for 2 ps pulses and 3.5 μW for 20-ps pulses. At low input powers, the SHG average power conversion efficiency of the 2-ps system was more than 10 times larger than the 20 ps system. As power was increased, the SH power saturated and conversion efficiency decreased to nearly equal to the 20-ps system which remained consistent over the same power range. This is attributed to a reduction in third-order nonlinear effects, a smaller pulse spectral width that overlaps better with the conversion bandwidth, and less pulse walkoff for the 20-ps pulses. Thus, by using 20-ps pulses over 2-ps pulses, we achieved similar output SH powers and potentially higher SH powers are possible since there was no observed saturation at high input power.

Proceedings Article | 26 August 2008 Paper

Integrated multi-channel nano-engineered optical hydrogen and temperature sensor detection systems for launch vehicles

M. Alam, J. Moreno, J. S. Aitchison, M. Mojahedi, A. Kazemi

Proceedings Volume 7095, 70950O (2008) https://doi.org/10.1117/12.807651

KEYWORDS: Hydrogen, Sensors, Temperature sensors, Integrated optics, Waveguides, Temperature metrology, Silicon, Absorption, Resonators, Fiber optics sensors

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Launch vehicles and other satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, launch vehicle industry and aerospace agencies are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. Therefore, there is a critical need for miniaturized sensors and instruments suitable for use in space applications. This paper describes a novel multi-channel integrated nano-engineered optical sensor to detect hydrogen and monitor the temperature. The integrated optic sensor is made of multi-channel waveguide elements that measure hydrogen concentration in real Time. Our sensor is based on the use of a high index waveguide with a Ni/Pd overlay to detect hydrogen. When hydrogen is absorbed into the Ni/Pd alloy there is a change in the absorption of the material and the optical signal in the waveguide is increased. Our design uses a thin alloy (few nanometers thick) overlay which facilitates the absorption of the hydrogen and will result in a response time of approximately few seconds. Like other Pd/Pd-Ni based sensors the device response varies with temperature and hence the effects of temperature variations must be taken into account. One solution to this problem is simultaneous measurement of temperature in addition to hydrogen concentration at the same vicinity. Our approach here is to propose a temperature sensor that can easily be integrated on the same platform as the hydrogen sensor reported earlier by our group. One suitable choice of material system is silicon on insulator (SOI). Here, we propose a micro ring resonators (MRR) based temperature sensor designed on SOI that measures temperature by monitoring the output optical power.

Proceedings Article | 11 February 2008 Paper

Slow light generation in a resonance photonic crystal

Igor Mel'nikov, Anton Knigavko, J. Stewart Aitchison, Clark Merchant

Proceedings Volume 6904, 69040A (2008) https://doi.org/10.1117/12.763068

KEYWORDS: Solitons, Photonic crystals, Slow light, Chemical species, Crystals, Optical storage, Phase shift keying, Amplitude modulation, Particles, Numerical analysis

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Proceedings Article | 26 September 2007 Paper

An integrated optic hydrogen sensor for fast detection of hydrogen

M. Alam, J. Moreno, J. Aitchison, M. Mojahedi

Proceedings Volume 6758, 67580D (2007) https://doi.org/10.1117/12.734674

KEYWORDS: Hydrogen, Sensors, Palladium, Waveguides, Integrated optics, Surface plasmons, Humidity, Signal attenuation, Polarization, Explosives

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Proceedings Article | 3 February 2006 Paper

Self-focusing, breakup, and trapping of Raman-shifted femtosecond pulses in homogeneous slab and weakly coupled arrays of nonlinear glass silica waveguides

Yoav Linzon, Dima Cheskis, Iftach Ilsar, Roberto Morandotti, Stewart Aitchison, Shimshon Bar-Ad

Proceedings Volume 5975, 59750T (2006) https://doi.org/10.1117/12.675574

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