Speakers : Athulya Thulaseedharan (UOttawa), Fatemeh Mousavi Karimi (UOttawa) and Sunzid Ahmed (USaskatchewan)
Date and time : April 8, 2026, 1:00 p.m. to 2:00 p.m. (Eastern time)
To attend or to get access to the recording of this seminar, please contact the program coordinator (genevieve.boudreau@inrs.ca).
First talk : Design and Modelling of Ring Resonators for InGaAsP-on-Insulator Platform, by Athulya Thulaseedharan (University of Ottawa), 1:00 p.m.
We examine one of the composite building blocks of photonic integration technology: ring resonators. With a focus on optical communications, Indium Gallium Arsenide Phosphide (InGaAsP) is chosen as the material of interest because of its unique combination of properties. It offers stronger optical nonlinearity than silicon and faster switching speeds than Aluminum Gallium Arsenide (AlGaAs), which is often referred to as the “silicon” of III–V materials. Additionally, InGaAsP is the only compound semiconductor capable of operating across the entire telecommunications bandwidth. Its ability to support both active and passive functionalities further enhances its suitability for enabling the integration of active and passive components within a single material platform.
A detailed investigation into the design and modeling of ring resonators on a promising InGaAsP-on-insulator (InGaAsP-OI) platform is presented, with an emphasis on their suitability for frequency-comb generation. We present the first comprehensive study of InGaAsP-OI ring resonators that incorporates nonlinear loss mechanisms such as two-photon absorption (TPA) and free-carrier effects (FCE), both of which are significant under realistic operating conditions at the 1550 nm C-band operating wavelength. Various approaches for engineering free-carrier lifetime are discussed, along with their relevance to optimizing the performance of these ring resonators.
Second talk : Subwavelength Engineering in III-V Semiconductors: A Pathway for Monolithic Photonic Integration, by Fatemeh Mousavi Karimi (University of Ottawa), 1:20 p.m.
Subwavelength engineering has emerged as a powerful tool in integrated silicon photonics, frequently enabling more efficient and compact design footprints. Subwavelength grating (SWG) structures allow refractive index customization in a purely geometric manner, avoiding the need to alter the waveguide material. However, silicon suffers from inherent material limitations such as an indirect energy bandgap, two-photon absorption in the telecommunication C-band, and a lack of intrinsic second-order nonlinearity. These hinder the use of silicon for active photonic components and for nonlinear applications. To overcome these barriers, our research explores the integration of SWG structures with III-V semiconductors, which commonly possess direct, tunable energy bandgaps and strong optical nonlinearities. Aluminum Gallium Arsenide (AlGaAs) is of particular interest among these compounds due to its negligible two-photon absorption losses, making it highly suitable for monolithic integration and nonlinear processes in optical telecommunication applications. This work demonstrates the application of subwavelength engineering techniques to the AlGaAs-on-Insulator platform for the design of fundamental integrated photonic building blocks, such as SWG waveguides and couplers.
Third talk : Host-Selective Bacterial Colonization Drives Root Microbiome Variation Across Arabidopsis thaliana Ecotypes, by Sunzid Ahmed (University of Saskatchewan), 1:40 p.m.
Plant-associated microbiomes, often referred to as a plant’s “second genome,” play a central role in regulating growth and stress tolerance. Yet, the molecular determinants guiding root–microbe interactions remain poorly understood. Here, we examined variation in root microbiome community composition across 32 natural Arabidopsis thaliana ecotypes, focusing on small molecular weight organic compounds (SMWOCs) released from roots into the rhizosphere, as potential drivers of microbial colonization. Plants were grown hydroponically under controlled conditions and inoculated with a defined synthetic community (SynCom) of 14 root-commensal bacteria. Amplicon sequencing of the 16S rRNA gene (V4 region) of root colonized bacteria revealed consistent detection of 11 of the SynCom strains across ecotypes, with substantial variation in relative abundance. Pseudomonas fluorescence CH229 emerged as the most differentially abundant strain, showing pronounced variation among ecotypes with highly divergent microbiome compositions. Mono-inoculation of Pseudomonas CH229 in ecotypes Wt-5 and Na-1 that differ the most in Pseudomonas CH229 abundance in the Arabidopsis root microbiome, demonstrated that differential abundance arises from variation in colonization efficiency between more compatible and less compatible hosts, indicating host-driven selective enrichment. Ongoing metabolomic analyses will assess correlations between root exuded SMWOCs and microbiome composition. Integrated metabolomic and transcriptomic analyses will identify root-derived chemical cues and bacterial genes underlying selective microbial recruitment, advancing mechanistic understanding of root–microbiome interactions with implications for sustainable agriculture.
For the full seminar series, visit the TrUST website or ultrafast-coast-to-coast.ca.
See you there!
