Ribal Georges Sabat

Ribal Georges Sabat
Royal Military College of Canada · Department of Physics

PhD

About

62
Publications
8,886
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618
Citations
Introduction
Prof. Sabat is an expert in optics and photonics, as well as in optical materials. He mainly conducts research on the laser-inscription of holographic optical nanostructures on photomechanical azobenzene thin-films, and their subsequent use in photonics applications, including the generation of surface plasmon resonance for incorporation in sensors, imagers and solar cells.
Additional affiliations
July 2019 - present
Royal Military College of Canada
Position
  • Professor (Full)
July 2015 - July 2019
Royal Military College of Canada
Position
  • Professor (Associate)
June 2010 - July 2015
Royal Military College of Canada
Position
  • Professor (Assistant)
Education
September 2006 - May 2009
Royal Military College of Canada
Field of study
  • Experimental Physics

Publications

Publications (62)
Article
Full-text available
Large-scale hierarchical macroscopic moire gratings resembling the surface structure of Peruvian lily flower petals are fabricated on azobenzene molecular glass thin films using a Lloyd’s mirror interferometer. It is shown that nanostructured linear and crossed moire gratings can be made with pitch values reaching a few millimeters. Also, using ato...
Article
Full-text available
We deposited homogeneous, thin, yellow-colored films of chitosan (Chi)-N,N-Dimethyl-4-(2-pyridylazo)aniline (PADA) dye from an acid Chi–PADA solution by spin-coating on glass substrates. We characterized Chi, PADA, and Chi–PADA films by ATR–FTIR spectroscopy, which revealed a slight shift of 3170 and 3268 cm−1 bands, indicating H-bonding between th...
Article
Full-text available
Two-dimensional Resonant Waveguide Crossed Gratings (RWCG) were fabricated on azobenzene molecular glass thin films and their resonance behavior was studied once placed in between orthogonally aligned polarizers. Normally-incident polychromatic light was transmitted and/or reflected from these RWCGs only in narrow positive peaks. In addition, the c...
Article
A simple inline holographic setup is used to fabricate holographic diffractive lenses using off-the-shelf components. The resulting surface relief gratings are inscribed directly in azobenzene-functionalized thin films with pitches that agree well with a theoretical Fresnel zone plate. The annular gratings have an outer radius of approximately 9 mm...
Article
Full-text available
This article introduces a bioinspired, cicada wing-like surface-enhanced Raman scattering (SERS) substrate based on template-stripped crossed surface relief grating (TS-CSRG). The substrate is polarization-independent, has tunable nanofeatures and can be fabricated in a cleanroom-free environment via holographic exposure followed by template-stripp...
Article
Full-text available
Plasmonic crossed surface relief gratings were fabricated using interference lithography. Their topographies were studied by AFM as a function of laser exposure time and their surface plasmon resonance at a gold-air interface was measured between crossed polarizers in transmission and in reflection modes. Both modes resulted in emitted plasmonic li...
Article
Full-text available
Silver-coated Crossed Surface Relief Gratings (CSRGs) are fabricated and used for imaging and detecting localized refractive index variations in inhomogeneous water-based solutions via polarization-contrast Surface Plasmon Resonance (SPR). When placed in between crossed polarizers, incident light was transmitted at intensity levels directly and pre...
Article
The rate of photomechanical formation of surface relief gratings (SRG) in thin films of azobenzene materials depends on their glass transition temperature (Tg), with an optimal Tg around 50-60 °C yielding the fastest SRG growth. Herein, the SRG growth of five analogous Disperse Red 1 molecular glasses with Tg values ranging from 9 to 71 °C was stud...
Article
A simple, yet precise, optical angle measurement device was developed by analyzing the light interference pattern from a modified Lloyd’s mirror interferometer combined with a CMOS camera sensor. The resulting spatially heterodyned signal was very sensitive to small angle changes from an incident low-power laser beam, with an accuracy better than 8...
Article
Full-text available
The unique plasmonic energy exchange occurring within metallic crossed surface relief gratings (CSRGs) has recently motivated their use as biosensors. However, CSRG-based biosensing has been limited to spectroscopic techniques, failing to harness their potential for integration with ubiquitous portable electronics. Here, we introduce biosensing via...
Article
Nanoscale-patterned azobenzene thin films were incorporated in organic solar cells to scatter incident light, thus increasing the optical path length of photons inside the active area. This ultimately led to significant power conversion efficiency (PCE) enhancements in the active layer. Specifically, the azobenzene thin films were patterned with tw...
Article
Large-scale surface relief diffraction gratings with pitches up to 20 μm were fabricated in thin films of azobenzene molecular glass using a single-step and mask-less photolithography process. A modified Lloyd’s mirror interferometer having two degrees of freedom generated an interference pattern that was incident on the azobenzene films. Some of t...
Article
Full-text available
Two-dimensional chirped-pitch crossed surface relief gratings (CP-CSRGs) were fabricated on azobenzene-functionalized thin films using a simple two-step procedure. The resulting gratings had a constant pitch in one direction and a varying (chirped) pitch in the orthogonal direction. They were coated with silver and tested for their ability to chang...
Article
Full-text available
Urinary tract infections (UTIs) are one of the major burdens on public healthcare worldwide. One of the primary causes of UTIs is the invasion of the urinary tract by uropathogenic Escherichia coli (UPEC). Improper treatment of bacterial infections like UTIs with broad-spectrum antibiotics has contributed to the rise of antimicrobial resistance, ne...
Preprint
Given the rise in the number of cases and their recurrences, Urinary Tract Infections (UTI) are one of the major burdens on public healthcare worldwide. Rapid, inexpensive and selective detection of Uropathogenic E. coli (UPEC), a major contributor to UTIs, is the need of the hour for effective treatment, given the rise of antibiotic-resistant bact...
Article
Full-text available
Non-uniform surface relief diffraction gratings were laser-inscribed on azobenzene molecular glass thin films using a modified Lloyd's mirror interferometer. The azobenzene films were exposed to an adjustable interference pattern produced by the recombination of collimated and spherically divergent laser wave fronts. The localized pitch, grating ve...
Article
A thermo-optical process was developed for the erasure of surface relief gratings (SRG) inscribed on various films of mexylaminotriazine molecular glasses functionalized with different azobenzene chromophores, as well as azobenzene polymer films. Irradiation of the samples with a CO2 laser beam causes localized heating of the soda lime substrate, w...
Article
Full-text available
Large-scale linear diffraction gratings with gradually varying pitch were photo-inscribed onto the surface of azobenzene thin films using a 532 nm laser and a modified Lloyd mirror set-up. By placing a cylindrical lens in front of the direct half of the inscribing beam, gratings with a chirping rate as high as 12.9 nm/mm were produced. Subsequently...
Article
Full-text available
We present an original, low-cost nanoplasmonic (bio)sensor based on crossed surface relief gratings (CSRGs) generated from orthogonally superimposed surface relief gratings (SRGs) on gold-coated azo-glass substrate. This surface plasmon resonance (SPR)-based sensing approach is unique, since the light transmitted through a CSRG is zero except in th...
Article
Irradiation of azomaterials causes various photophysical and photomechanical effects that can be exploited for the preparation of functional materials such as surface relief gratings (SRGs). Herein, we develop and apply an efficient strategy to optimize the SRG inscription process by decoupling, for the first time, the important effects of the azo...
Article
Nucleation and growth of spontaneous surface relief gratings (SSRGs) on a Disperse Red 1 (DR1) glass-forming derivative were investigated. No interference pattern is applied and surface patterning is induced using single-beam irradiation: the gratings are self-organized. Grating growth is assumed to initiate from an interference pattern formed betw...
Article
The second-order nonlinear optical coefficients of thin films of mexylaminotriazine-functionalized azobenzene molecular glass derivatives were measured using second harmonic generation. The thin films were poled using a custom corona poling set-up and the second harmonic light from a pulsed 1064-nm laser was detected. Four out of the six tested com...
Article
The influence of the supramolecular interaction type - hydrogen bonding, proton transfer, and pure ionic bonding - on photoresponsive behavior, particularly surface relief grating (SRG) inscription, has been investigated using a homopolymer with an ambient temperature glass transition (Tg). To this end, poly(dimethylaminoethyl methacrylate) (PDMAEM...
Article
Real-time surface plasmon modulation was achieved by electrically varying the pitch of a nanoscale surface relief diffraction grating inscribed on an azobenzene thin film covered with a layer of silver. The azobenzene film was spin coated on an electrostrictive Lead Lanthanum Zirconate Titanate (PLZT) ceramic substrate and a combination of DC bias...
Article
Nano-scale surface patterns were observed in thin films of mexylaminotriazine-functionalized glasses containing polar groups upon the application of an electric field at temperatures over their glass transition temperatures (Tg). This phenomenon occurred due to the dewetting process initiated by external electric field instabilities on the films. T...
Article
The supramolecular assembly of photoactive azobenzenes with passive polymers via halogen or hydrogen bonding is a cost-effective way to design materials for various photomechanical applications that convert light energy directly into macroscopic motion, for instance, in all-optical surface patterning and photochemical imaging of plasmonic structure...
Article
Full-text available
Azobenzene-containing materials exhibit various photomechanical properties, including the formation of surface relief gratings (SRG) when irradiated with two interfering laser beams. In a recent study, a novel glass-forming derivative of Disperse Red 1 (DR1) with a mexylaminotriazine group was synthesized in high yield with a simple and efficient p...
Article
Full-text available
Chirped-pitch nanoscale circular surface-relief diffraction gratings were photoinscribed on thin films of a Disperse Red 1 functionalized material using a holographic technique. A truncated conical mirror splits and redirects a converging or diverging laser beam, resulting in an interference pattern of concentric circles with a chirped pitch that c...
Article
Electrically insulating polyolefin composites containing well-dispersed multiwall carbon nanotubes up to 3 wt.-% are subjected to AC electric fields in the range of 71–212 kV m−1. Their resulting filler structure, DC conductivity, and AC dielectric properties are compared with the respective properties of their non-electrified and annealed counterp...
Article
Novel metallic light-interfering fixtures were designed and fabricated in order to achieve a laser interference pattern of constant-pitch, concentric and sinusoidal light variations. These fixtures consisted of annular rings with the inner diameter shaped conically. Azobenzene-containing solid thin-films were subsequently placed behind the fixture...
Article
Methodical and intensive surface plasmon (SP) excitation trials were carried out on various dielectric-metal interfaces to optimize plasmonic photocurrent enhancements in organic P3HT-PCBM photovoltaic thin films. The SPs were optically excited via the diffraction grating method using single, crossed, and parallel grating schemes, with trials yield...
Article
Full-text available
Circular surface-relief diffraction gratings with a constant pitch were photo-inscribed on thin films of a disperse red 1 functionalized glass-forming compound using a novel holographic technique. Various light-interfering metallic fixtures, which consisted of annular rings with a sloped and polished inner surface, were designed and fabricated. Eac...
Article
Copolymers of 2-ethylhexyl acrylate (EHA) and cholesteryloxycarbonyl-2-hydroxymethacrylate (CEM) were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Supramolecular complexes of these copolymers with carbon nanotubes (CNTs) were soluble in THF, toluene, and isooctane. The colloidal solutions remained stable for m...
Article
Full-text available
Materials containing azobenzene chromophores exhibit photomechanical behaviors, including the formation of surface relief gratings (SRG) caused by irradiation with two interfering laser beams. While azo-functionalized polymers were extensively studied, small molecules offer the advantage of being monodisperse species, which translates into easier s...
Article
Various superimposed chirped relief gratings, acting as diffracting holographic lenses, were photo-inscribed on azopolymer films upon exposure to the interference pattern of a plane and a curved laser light wavefronts. Depending on the configuration used, this resulted in incident light being focused independently of polarization along the 0th or 1...
Article
Full-text available
Various superimposed chirped relief gratings, acting as diffracting holographic lenses, were photo-inscribed on azo-polymer films upon exposure to the interference pattern of a plane and a curved laser light wavefronts. Depending on the configuration used, this resulted in incident light being focused independently of polarization along the 0th or...
Conference Paper
Surface plasmons were optically excited via the diffraction grating method using single, crossed and parallel grating schemes. Photocurrent enhancements up to 355% were demonstrated in P3HT-PCBM organic solar cells for TE and TM polarized light.
Article
a b s t r a c t Surface plasmon resonance platforms based on laser inscribed azo polymer surface relief diffraction gratings were used to detect the binding of organic and biological molecules. Optical sensors were assem-bled to operate in transmission mode, resulting in a very simple setup. This new approach is observed to present a high sensitivi...
Article
The light transmission through a Lead Lanthanum Zirconate Titanate (PLZT) ceramic film, having a relaxor ferroelectric composition of (9.5/65/35) was modulated at both the first and second harmonic frequencies to that of an applied field. Large changes were observed in the optical path difference within the material due to a combination of the elec...
Article
Full-text available
The transmission of light through a lead lanthanum zirconate titanate ceramic film, having a relaxor ferroelectric composition of (9.5/65/35), exhibited a Fabry-Pérot interference pattern. Upon the application of an electric field, the transmitted irradiance was modulated at both the first and second harmonic frequencies to that of the applied fiel...
Article
A 260 nm layer of organic bulk heterojunction blend of the polymer poly (3-hexylthiophene) (P3HT) and the fullerene [6,6]-phenyl C61-butyric (PCBM) was spin-coated in between aluminum and gold electrodes respectively on top of a laser inscribed azo polymer surface relief diffraction grating. Angle dependent surface plasmons (SP) with a large band g...
Article
The real-time thermo-optical properties of thin-film relaxor ferroelectric (9/65/35) lead lanthanum zirconate titanate (PLZT) films (∼2 μm) were investigated and compared to identical composition of thick PLZT ceramics (∼1 mm). Since PLZT absorbs strongly in the far-infrared, a CO2 laser beam (λ = 10.6 μm) was used to create a Gaussian temperature...
Article
Full-text available
We study the polarization conversion from horizontally polarized to vertically polarized light (or vice versa) that occurs when light is incident on a cross-corrugated metal surface. The conversion is due to the optical energy exchange between the surface plasmon (SP) resonances at the metal-dielectric interface of the surface. The angular and wave...
Article
Full-text available
A polarization conversion of linearly polarized light incident on a cross-corrugated metal surface may occur due to the optical energy exchange between the surface plasmon (SP) resonances at the metal-dielectric interface. In this paper, the angular and wavelength dependence of the SP-induced polarization conversion was studied in transmission as a...
Article
Full-text available
A 260 nm layer of organic bulk heterojunction blend of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene [6,6]-phenyl C61-butyric (PCBM) was spin-coated in between aluminum and gold electrodes, respectively, on top of a laser inscribed azo polymer surface-relief diffraction grating. Angle-dependent surface plasmons (SPs) with a large band...
Article
Full-text available
Azobenzene polymer surface relief diffraction gratings were inscribed on relaxor ferroelectric Lead Lanthanum Zirconate Titanate (PLZT) thin films having a (9/65/35) composition. Resonance structures were observed in the reflected intensity spectra of a laser light beam onto these films, indicating coupling of the incident light. An ac electric fie...
Article
Full-text available
The change in the transverse refractive indices of clamped transparent relaxor ferroelectric PLZT ceramics, having a composition of (9.5/65/35) and (9.0/65/35), were measured as a function of various ac and dc electric fields, as well as frequency and elapsed time, using an interferometric technique. It was found that the refractive index changed o...
Article
Changes in the refractive indices Δn1 and Δn3 of clamped transparent relaxor ferroelectric (9.5/65/35) and (9.0/65/35) PLZT ceramics were measured as a function of temperature ranging from −30°C to 60°C, and at various transversely applied DC electric fields E3DC. It was found that the refractive index of both PLZT compositions increased linearly w...
Article
Full-text available
Relaxor lead lanthanum zirconate titanate (PLZT) thin films, with compositions of (7/65/35), (8/65/35), and (9/65/35), have been investigated as optical waveguides. Resonant structures were observed in the reflected light beam that passes through these thin films after coupling with a laser-inscribed azo polymer surface relief diffraction grating....
Thesis
Smart materials are playing an increasingly important role in our ever-evolving technology because they can fulfill a multi-dimensional role in the development of smaller, cheaper and more effective devices. Future advances in the design and development of new applications heavily relies on our fundamental understanding of the behaviour of their co...
Article
Full-text available
The relative permittivity and dielectric loss tangent of transparent lead lanthanum zirconate titanate (PLZT) (9.5/65/35) and (9.0/65/35) ceramics were measured as a function of temperature, ranging from -60 to 100 ° C , and as a function of frequency, ranging from 0.12 to 5000 kHz. Diffuse maxima were observed in the complex permittivity plots of...
Conference Paper
Resonance characterisation has been used to determine the variation of the independent piezoelectric, elastic, and dielectric material coefficients, as well as the electromechanical coupling factors, of typical soft and hard lead zirconate titanate (PZT) ceramics as a function of temperature ranging from -165degC to 195degC. The piezoelectric coeff...
Article
Full-text available
We have used resonance methods to determine the variation of all the independent piezoelectric, elastic, and dielectric material coefficients, as well as the corresponding electromechanical coupling factors, of soft and hard doped piezoelectric lead zirconate titanate (PZT) ceramics with compositions near the morphotropic phase boundary, as a funct...
Article
Full-text available
Resonance methods were used to determine the variation of several piezoelectric, elastic and dielectric constants, as well as the corresponding electromechanical coupling factors of soft and hard doped Pb(ZrxTi1-x)O3 (PZT) ceramics, with compositions near the morphotropic phase boundary (MPB), as a function of temperature ranging from -165 °C to 19...
Article
Acoustic sensors and actuators often utilize piezoelectric transducers in active methods of noise and vibration control and in other smart applications. The increasing range of these applications requires the piezoelectric materials to be used under a variety of conditions that include large applied AC fields, DC bias fields, applied stresses and a...

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