Achieving High-Precision Attenuation Coefficient Measurement in Optical Coherence Tomography.

In this study, we aim to validate the analytical Cramer-Rao lower bound (CRLB) equation for determining attenuation coefficients using a 1310 nm Optical Coherence Tomography (OCT) system. Our experimental results successfully confirm the validity of the equation, achieving unprecedented precision with a standard deviation below 0.01 mm for intralipid samples.

Squeezed dual-comb spectroscopy.

Optical frequency combs have enabled unique advantages in broadband, high-resolution spectroscopy and precision interferometry. However, quantum mechanics ultimately limits the metrological precision achievable with laser frequency combs. Quantum squeezing has led to significant measurement improvements with continuous wave lasers, but experiments demonstrating metrological advantage with squeezed combs are less developed.

Infection Rate and Risk Factors of SARS-CoV-2 Infection in Retail Workers at the Onset of the COVID-19 Pandemic, Quebec, Canada.

During the pandemic, client-facing workers were perceived to be at greater risk of SARS-CoV-2 infection. This study investigated the risk factors for SARS-CoV-2 infection among a cohort of 304 retail workers in the Quebec City metropolitan area. After providing consent, participants were interviewed to gather information on demographic, socioeconomic, behavioural, and occupational variables.

Longitudinal determination of seroprevalence and immune response to SARS-CoV-2 in a population of food and retail workers through decentralized testing and transformation of ELISA datasets.

Background: Since the onset of the global COVID-19 pandemic in early 2020, numerous studies have been conducted worldwide to understand our immune response to the virus and to vaccination. This study investigates the humoral response elicited by SARS-CoV-2 infection and by vaccination in the poorly studied population of food and retail workers. These occupations were classified as essential by the Public Health Agency of Canada, potentially placing this population at greater risk of infection.

Absolute depth-resolved optic axis measurement with catheter-based polarization sensitive optical coherence tomography.

Imaging depth-resolved birefringence and optic axis orientation with polarization sensitive optical coherence tomography (PS-OCT) unveils details of tissue structure and organization that can be of high pathophysiologic, mechanistic, and diagnostic value. For catheter-based PS-OCT, the dynamic rotation of the fiber optic probe, in addition to the polarization effects of the system components, complicates the reliable and robust reconstruction of the sample's optic axis orientation. Addressing this issue, we present a new method for the reconstruction of absolute depth-resolved optic axis orientation in catheter-based PS-OCT by using the intrinsic retardance of the protecting catheter sheath as a stable guide star signal.

Relativistic Electrons from Vacuum Laser Acceleration Using Tightly Focused Radially Polarized Beams.

We generate a tabletop pulsed relativistic electron beam at 100 Hz repetition rate from vacuum laser acceleration by tightly focusing a radially polarized beam into a low-density gas. We demonstrate that strong longitudinal electric fields at the focus can accelerate electrons up to 1.43 MeV by using only 98 GW of peak laser power.

Graphics card-based real-time processing for dual comb interferometry.

The technique of performing interferometry with two optical frequency combs is used by an increasing number of research groups and even for field deployed commercial applications. Real-time interferogram acquisition, correction, and averaging are, however, still not broadly accessible. This limits the deployment and wider adoption of this high resolution, high sensitivity technique.

All-reflective tethered capsule endoscope for multimodal optical coherence tomography in the esophagus.

Significance: Esophageal cancer is becoming increasingly prevalent in Western countries. Early detection is crucial for effective treatment. Multimodal imaging combining optical coherence tomography (OCT) with complementary optical imaging techniques may provide enhanced diagnostic capabilities by simultaneously assessing tissue morphology and biochemical content.

Wavelength-swept spontaneous Raman spectroscopy system improves fiber-based collection efficiency for whole brain tissue classification.

Significance: Raman spectroscopy is a valuable technique for tissue identification, but its conventional implementation is hindered by low efficiency due to scattering. Addressing this limitation, we are further developing the wavelength-swept Raman spectroscopy approach.

Aim: We aim to enhance Raman signal detection by employing a laser capable of sweeping over a wide wavelength range to sequentially excite tissue with different wavelengths, paired with a photodetector featuring a fixed narrow-bandpass filter for collecting the Raman signal at a specific wavelength.

Live virus neutralizing antibodies against pre and post Omicron strains in food and retail workers in Québec, Canada.

Background: Measuring the ability of SARS-CoV-2 antibodies to neutralize live viruses remains an effective approach to quantify the level of protection of individuals. We assessed the neutralization activity against the ancestral SARS-CoV-2, Delta, Omicron BA.1, BA.

Microflow sensing and control using an in-channel birefringent biomembrane.

This study describes the function, optimization, and demonstration of a new class of passive, low-cost microfluidic flow meters based on birefringent chitosan biomembranes analyzed by polarized microscopy. We subjected the membrane to dynamic flow conditions while monitoring the real-time response of its optical properties. We obtained figures of merit, including the linear response operating range (0 to 65 μL min), minimum response time (250 ms), sensitivity (2.

Stable, intense supercontinuum light generation at 1 kHz by electric field assisted femtosecond laser filamentation in air.

Supercontinuum (SC) light source has advanced ultrafast laser spectroscopy in condensed matter science, biology, physics, and chemistry. Compared to the frequently used photonic crystal fibers and bulk materials, femtosecond laser filamentation in gases is damage-immune for supercontinuum generation. A bottleneck problem is the strong jitters from filament induced self-heating at kHz repetition rate level.

Multi-point calorimeter using distributed fiber Bragg gratings for small field dosimetry in radiotherapy.

Background: The interest of using fiber Bragg gratings (FBGs) dosimeters in radiotherapy (RT) lies in their (i) microliter detection volume, (ii) customizable spatial resolution, (iii) multi-point dose measurement, (iv) real-time data acquisition and (v) insensitivity to Cherenkov light. These characteristics could prove very useful for characterizing dose distributions of small and nonstandard fields with high spatial resolution.

Purpose: We developed a multi-point FBGs dosimeter customized for small field RT dosimetry with a spatial resolution of 1 mm.

Tailoring ultrabroadband near-infrared luminescence in Bi-doped germanosilicate glasses.

Bi-doped glasses and optical fibers are extensively studied since they present broadband optical amplification in the near-infrared region (NIR), in which the optical telecommunication industry greatly depends for the transmission of optical signals. There are many scientific challenges about the NIR luminescent emissions from Bi ions, such as understanding its origin and further improving the associated optical amplification capacity. In this work, Bi-doped germanosilicate glass compositions with ultrabroadband NIR luminescence were fabricated, in the range of 925-1630 nm, which covers O, E, S, C, and L-telecommunication bands.

Bi-coloured enhanced luminescence imaging by targeted switch on/off laser MEF coupling for synthetic biosensing of nanostructured human serum albumin.

In this communication luminescent bioconjugated human serum albumin nanostructures (HSA NPs) with tiny ultraluminescent gold core-shell silica nanoparticles (Au@SiO-Fl) were designed with enhanced bi-coloured luminescence properties. The HSA NPs were obtained from Human Serum Albumin free (HSA free) through the desolvation method, and Au@SiO-Fl, through modified Turkevich and Störber methods. In this manner, porous HSA Nanostructures of 150.

Effect of Photoinitiators Doped in PDMS for Femtosecond-Laser Writing: Characterization and Outcomes.

Herein, we have characterized in depth the effect of femtosecond (fs)-laser writing on various polydimethylsiloxane (PDMS)-based composites. The study combines systematic and nanoscale characterizations for the PDMS blends that include various photoinitiators (organic and inorganic agents) before and after fs-laser writing. The results exhibit that the photoinitiators can dictate the mechanical properties of the PDMS, in which Young's modulus of PDMS composites has higher elasticity.

Towards REPO nanocrystal-doped optical fibers for distributed sensing applications.

Rayleigh scattering enhanced nanoparticle-doped optical fibers, for distributed sensing applications, is a new technology that offers unique advantages to optical fiber community. However, the existing fabrication technology, based on in situ grown alkaline earth nanoparticles, is restricted to few compositions and exhibit a great dependence on many experimental conditions. Moreover, there is still several uncertainties about the effect of drawing process on the nanoparticle characteristics and its influence on the scattering enhancement and the induced optical loss.

Unveiling Structural Insights into Nanocrystal-Doped Optical Fibers via Confocal Raman Microscopy.

An in-depth characterization of nanoparticle-doped optical fibers is crucial to understand the potential new functionalities of the engineered glass and thus their applicability fields. The high temperatures of the manufacturing process strongly affect the nanoparticle features, and therefore, their analysis is necessary after fiber drawing. However, the difficulties associated with the use of atomic resolution microscopies to analyze the nanoparticle features in the fiber core, mainly related to sample preparation and expensive costs, usually prevent their study.

Millimetric scale two-photon Bessel-Gauss beam light sheet microscopy with three-axis isotropic resolution using an axicon lens.

Significance: Typical light sheet microscopes suffer from artifacts related to the geometry of the light sheet. One main inconvenience is the non-uniform thickness of the light sheet obtained with a Gaussian laser beam.

Aim: We developed a two-photon light sheet microscope that takes advantage of a thin and long Bessel-Gauss beam illumination to increase the sheet extent without compromising the resolution.

Enhancing Evanescent Wave Coupling of Near-Surface Waveguides with Plasmonic Nanoparticles.

Evanescent field excitation is a powerful means to achieve a high surface-to-bulk signal ratio for bioimaging and sensing applications. However, standard evanescent wave techniques such as TIRF and SNOM require complex microscopy setups. Additionally, the precise positioning of the source relative to the analytes of interest is required, as the evanescent wave is critically distance-dependent.

Demonstration of laser cooling in a novel all oxide GAYY silica glass.

We demonstrate laser induced cooling in ytterbium doped silica (SiO) glass with alumina, yttria co-doping (GAYY-Aluminum: Yttrium: Ytterbium Glass) fabricated using the modified chemical vapour deposition (MCVD) technique. A maximum temperature reduction by - 0.9 K from room temperature (296 K) at atmospheric pressure was achieved using only 6.

Current Advances in Nanotechnology for the Next Generation of Sequencing (NGS).

This communication aims at discussing strategies based on developments from nanotechnology focused on the next generation of sequencing (NGS). In this regard, it should be noted that even in the advanced current situation of many techniques and methods accompanied with developments of technology, there are still existing challenges and needs focused on real samples and low concentrations of genomic materials. The approaches discussed/described adopt spectroscopical techniques and new optical setups.

Assessment of the longitudinal humoral response in non-hospitalized SARS-CoV-2-positive individuals at decentralized sites: Outcomes and concordance.

Introduction: Early in the COVID-19 pandemic, reagent availability was not uniform, and infrastructure had to be urgently adapted to undertake COVID-19 surveillance.

Methods: Before the validation of centralized testing, two enzyme-linked immunosorbent assays (ELISA) were established independently at two decentralized sites using different reagents and instrumentation. We compared the results of these assays to assess the longitudinal humoral response of SARS-CoV-2-positive (i.