Sébastien Loranger

• PhD
• Assistant professor at Polytechnique Montréal

Distributed feedback (DFB) fiber Bragg gratings (FBG) are widely used as narrow-band filters and single-mode cavities for lasers. Recently, a nonlinear generation has been shown in 10–20 cm DFB gratings in a highly nonlinear fiber. First, we show in this Letter a novel fabrication technique of ultra-long DFBs in a standard fiber (SMF-28). Second, w...

We demonstrate a simple technique for implementing long period grating (LPG) structures by the use of a 3D printer. This Letter shows a way of manipulating the mode coupling within an optical fiber by applying stress through an external 3D printed periodic structure. Different LPG lengths and periods have been studied, as well as the effect of the...

We present a technique to improve signal strength, and therefore sensitivity in distributed temperature and strain sensing (DTSS) using Frequency domain Rayleigh scatter. A simple UV exposure of a hydrogen loaded standard SMF-28 fibre core is shown to enhance the Rayleigh back-scattered light dramatically by ten-fold, independent of the presence of...

Rayleigh scatter in optical fiber communication systems has long been considered a nuisance as a loss mechanism, although applications have used such scatter to probe the fiber for faults and propagation loss using time domain reflectometry (OTDR). It is however only with the development of Frequency domain reflectometry (OFDR) and coherent-phase O...

We demonstrate a new type of sensor incorporated directly into Corning Gorilla glass, an ultraresistant glass widely used in the screen of popular devices such as smartphones, tablets, and smart watches. Although physical space is limited in portable devices, the screens have been so far neglected in regard to functionalization. Our proof-of-concep...

We report enhanced slow-light characteristics of two types of first-order waveguide dot-Bragg gratings (DBGs) inscribed by femtosecond laser in bulk glass. By varying the offset between the waveguide and dot array, we optimize the group delay. Model-I and Model-II DBGs are achieved using single- and double-laser-pass waveguides, respectively, with...

We report a second-order waveguide line-Bragg grating (WLBG) directly written with femtosecond laser in bulk glass by using “offset” to exploit the enhanced slow-light effect. This design only employs a single-laser-pass waveguide (SLPWG) with a refractive index change of 1.1×10^(−3), to achieve effective light propagation. The SLPWG is first writt...

We report a strength-enhanced waveguide second-order line-Bragg grating (WLBG) directly written with femtosecond laser in bulk glass by using “offset” to exploit the slow-light effect. This design eschews the use of multiple waveguides and/or waveguide bundles for light guiding. Instead, it only employs a single-laser-pass waveguide (SLPWG) with a...

We study the generation of narrowband terahertz (THz) pulses by stimulated Raman scattering and molecular modulation in hydrogen-filled hybrid hollow-core fibers. Using a judicious combination of materials and transverse structures, this waveguide design enables simultaneous confinement of optical and THz signals with reasonably low attenuation, as...

We show that the use of random optical grating using UV exposure (ROGUE) can significantly reduce the noise floor of an optical frequency domain reflectometry (OFDR) measurement of Faraday rotation in the polarization. We compare it with unexposed spun fiber, which shows a S/P minimum ratio (signal noise floor) 20 dB higher than when using our ROGU...

Single-step writing of Bragg grating waveguide is obtained by externally modulating the fs laser pulse picker using a waveform generator, which delivers a controlled number of pulses to induce refractive-index changes at each sub-Bragg period.

We demonstrate the advantage of random fiber Bragg grating for distributed magnetic and current sensing. The 40 dB signal increase of the gratings allows a measurement down to 10 mT with 8 cm spatial resolution.

We report the impact of position offset on spectrum and polarization dependence of waveguide line-Bragg grating (WLBG) which was inscribed via femtosecond laser (fs-laser) in low-iron bulk glass. Employing a single scan for both waveguide (WG) and line grating, with three Z-offset values between them, we observe a 6.2 dB transmission (Tx) dip at 15...

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...

In this work we demonstrate the integration of a spectrometer directly into smartphone screen by femtosecond laser inscription of a weak Raman–Nath volume grating either into the Corning Gorilla glass screen layer or in the tempered aluminosilicate glass protector screen placed in front of the phone camera. Outside the thermal accumulation regime,...

The dispersion relation for the helical Bloch modes in this paper contains an error, which affects Equation (3) in the original manuscript, as well as Fig. 2. Otherwise the conclusions of the paper are unaffected.

Femtosecond laser direct-writing is an attractive technique to fabricate fiber Bragg gratings and to achieve through-the-coating inscription. In this article, we report the direct inscription of high-quality first-order gratings in optical fiber, without the use of an index-matching medium. A new alignment technique based on the inscription of weak...

This study aims at identifying compounds incorporated into Polydimethylsiloxane (PDMS) which produce large refractive index change under fs laser exposition, potentially leading to optimal writing of waveguides or photonic devices in such a soft host. Germanium derivative, titania and zirconite derivatives, benzophenone (Bp), irgacure-184/500/1173...

We present a FBG fabrication process using a multi-pulse femtosecond direct-writing scheme, preceded by a fiber core mapping through weak probe grating. Arbitrary apodization is written with high spatial resolution of only a few periods.

We report the structural and optical properties of Nd:YAB (NdxY1−x Al3(BO3)4)-nanoparticle-doped PDMS elastomer films for random lasing (RL) applications. Nanoparticles with Nd ratios of x = 0.2, 0.4, 0.6, 0.8, and 1.0 were prepared and then incorporated into the PDMS elastomer to control the optical gain density and scattering center content over...

We report the structural and optical properties of Nd:YAB (Nd x Y 1−x Al 3 (BO 3 ) 4 )-nanoparticle-doped PDMS elastomer films for random lasing (RL) applications. Nanoparticles with Nd ratios of x = 0.2, 0.4, 0.6, 0.8, and 1.0 were prepared and then incorporated into the PDMS elastomer to control the optical gain density and scattering center cont...

The possibility to perform time-resolved spectroscopic studies in the molecular fingerprinting region or extending the cutoff wavelength of high-harmonic generation has recently boosted the development of efficient mid-infrared (mid-IR) ultrafast lasers. In particular, fiber lasers based on active media such as thulium or holmium are a very active...

The possibility of performing time-resolved spectroscopic studies in the molecular fingerprinting region or extending the cut-off wavelength of high-harmonic generation has recently boosted the development of efficient mid-infrared ultrafast lasers. In particular, fibre lasers based on active media such as thulium or holmium are a very active area...

Optical fiber modes carrying orbital angular momentum (OAM) have many applications, for example in mode-division-multiplexing for optical communications. The natural guided modes of N-fold rotationally symmetric optical fibers, such as most photonic crystal fibers, are helical Bloch modes (HBMs). HBMs consist of a superposition of azimuthal harmoni...

Sub-40 fs pulses at 1.8 pm are generated by pumping H2-filled hollow-core PCF with 300 fs, 1.03 pm fiber laser pulses pre-chirped to a duration of 640 fs. Conversion efficiencies of 50% are obtained.

Femtosecond laser written waveguides have been previously proposed as potential compact photonic devices in multimedia glass covers. The structural modification induced by laser irradiation may however affect the mechanical strength of this protective glass layer. Therefore, the impact of such femtosecond laser radiation on the mechanical strength...

We propose a novel device defined as Random Optical Grating by Ultraviolet or ultrafast laser Exposure (ROGUE), a new type of fiber Bragg grating (FBG), exhibiting a weak reflection over a large bandwidth, which is independent of the length of the grating. This FBG is fabricated simply by dithering the phase randomly during the writing process. Thi...

Taking advantage of quantum mechanics for executing computational tasks faster than classical computers¹ or performing measurements with precision exceeding the classical limit2,3 requires the generation of specific large and complex quantum states. In this context, cluster states⁴ are particularly interesting because they can enable the realizatio...

Laser-written waveguides in glass have many potential applications as photonic devices. However, there is little knowledge of the actual profile of the usually asymmetric refractive index (RI) change across the femtosecond (fs) laser–written waveguides. We show, here, a new nondestructive method to measure any symmetric or asymmetric two-dimensiona...

We implement on-chip generation of high-dimensional hyper-entangled states in the time- and frequency-domain, and transform them into d-level cluster states using a deterministic controlled phase gate. We then demonstrate measurement-based quantum computing operations and show the state’s high tolerance towards noise.

Fiber Bragg gratings are written for the first time into a three-fold rotationally symmetric twisted fiber with three cores, and the reflection of helical Bloch modes explored as the wavelength is tuned.

-phase-shifted distributed feedback, ultralong fiber Bragg gratings (FBGs) with Raman gain have been shown to be excellent ultranarrow single-frequency lasers that can be operated at any wavelength. However, these lasers have shown unusually low slope efficiency (1%–10%), while theoretical simulations predict a much higher (30%–60%) number. We beli...

A new technique for measuring the spatial and temporal structure of the poloidal field is presented, whereby the magnetic field causes the polarization of light traveling through an optical fiber to rotate via the Faraday effect by an amount proportional to the strength of the field oriented along the fiber. In fiber optic pulsed polarimetry, chang...

Intra-arterial liver cancer therapies such as transarterial chemoembolization (TACE) are the preferred therapeutic approaches for advanced hepatocellular carcinoma (HCC). However, these palliative techniques are challenging for delivering therapeutic agents selectively in the tumor without real-time 3D visualization of the catheter within the hepat...

Distributed feedback Raman fiber lasers with π- phase-shifted uniform gratings are modelled and simulated in the steady state, to optimize their performance. Using parameters of realistic devices, it is found that the position change of the π-phaseshift in a constant-strength uniform grating has a significant impact on the laser performance includi...

Single-frequency laser sources have found a great number of applications, but are difficult to implement and suffer from poor robustness, poor quality (linewidth and stability), and are generally expensive to fabricate. One solution for a cheaper and simpler single-frequency source is a π -phase-shifted distributed feedback (DFB) fiber Bragg gratin...

We report the performance of a single frequency Raman DFB fiber laser operating at a wavelength of 1178-nm in which stimulated Brillouin scattering (SBS) and active burst-pulse Q-switching are observed and influence the laser performance.

Optical fiber technology has become a very powerful tool for distributed temperature (strain and refractive index) sensing, and can be used to monitor critical infrastructures such as bridges, aircrafts, pipelines, etc. Stimulated Brillouin scattering (SBS) in optical fibers used for distributed sensing utilizing the first Stokes order, is limited...

We present a fabrication technique for ultra-long fiber Bragg gratings (FBGs) involving a phase correction in a continuous direct writing scheme. This allows for the first time, repeatable fabrication of high quality ultra-long FBGs.

Distributed feedback (DFB) fiber lasers have been demonstrated to be excellent narrow-linewidth (kilohertz range) single-frequency laser sources. However, this type of laser is normally limited to rare-earth-doped fibers. Raman gain offers an alternative, operating at any arbitrary wavelength. We demonstrate here linearly polarized, single-frequenc...

Ultra-long fiber Bragg gratings (FBGs), i.e., FBGs of several tens of cm in length, have attracted much attention in the last few decades for their potential applications in advanced devices. Although numerous fabrication methods as well as ultra-long functionalized FBGs have been proposed and demonstrated successfully, such devices are difficult t...

Many applications of optical fiber, such as specialized fiber Bragg gratings (FBGs), require high uniformity of a fiber’s refractive index (RI) along its length. We show here that the mode effective index of most fibers is not constant, even on a short length scale. To help improve fiber manufacturing and selection, we demonstrate a technique for c...

We demonstrate a novel approach to enhance the precision of surgical needle shape tracking based on distributed strain sensing using optical frequency domain reflectometry (OFDR). The precision enhancement is provided by using optical fibers with high scattering properties. Shape tracking of surgical tools using strain sensing properties of optical...

Fibers used for long grating DFB Raman lasers suffer from imperfections that can have a significant impact on performance. We demonstrate a powerful scheme to compensate for these defects to enable the replication of DFB Raman Lasers

We experimentally and theoretically investigate how to control Stokes waves generated by SBS. A proper change of two pump powers results in increasing the number of Stokes waves, useful for sensitivity enhancement of distributed sensors.

We experimentally and theoretically investigate the generation of Stokes waves and the dynamics of pulses produced by cascaded stimulated Brillouin scattering (SBS) in a resonator, including a highly nonlinear fiber (HNLF) and an in-cavity erbium-doped fiber amplifier (EDFA) forming a multi-wavelength Brillouin erbium-doped fiber laser system. Usin...

This paper provides the first detailed temporal characterization of a multi-wavelength-Brillouin–erbium fiber laser (MWBEFL) by measuring the optical intensity of the individual frequency channels with high temporal resolution. It is found that the power in each channel is highly unstable due to the excitation of several cavity modes for typical co...

We propose here a new alternative to provide real-time device tracking during minimally invasive interventions using a truly-distributed strain sensor based on optical frequency domain reflectometry (OFDR) in optical fibers. The guidance of minimally invasive medical instruments such as needles or catheters (ex. by adding a piezoelectric coating) h...

Laser cooling with anti-Stokes fluorescencewas predicted by Pringsheim in 1929, but for solids was only demonstrated in 1995. There are many difficulties which have hindered laser assisted cooling, principally the chemical purity of a sample and the availability of suitable hosts. Recent progress has seen the cooled temperature plummet to 93K in Yb...

glass has a unique combination of optical properties, such as wide transparency in the infrared region and a high nonlinear coefficient. Recently, intense research has been conducted to improve photonic devices using thin materials. In this Letter, highly uniform rectangular single-index and 2 dB/m loss step-index optical tapes have been drawn by t...

This paper describes our recent work on the nonlinear optical applications of up to one meter long fiber Bragg gratings. We describe a technique for writing gratings including uniform, random, and distributed feedback structures. We demonstrate enhanced Rayleigh scatter through UV exposure of optical fiber, and stimulated Brillouin emission in stan...

We demonstrate an enhancement of up to 40 dB in the optical scatter in 213nm wavelength UV-exposed optical fibers, allowing high-resolution shape, temperature and strain sensing.

We demonstrate stimulated Brillouin scattering (SBS) in standard fiber using ultra-long distributed feedback (DFB) fiber Bragg gratings (FBG). This is the first observation of SBS in standard fiber with a DFB.

We have created affordable tunable optical fiber filters using 3D printed periodic structures acting as long fiber period grating.

Distributed temperature and strain sensing (DTSS) using optical fibre has many applications in monitoring the security and stability of infrastructure. Early detection is important to avoid catastrophic faults from occurring. This requires enhanced sensitivity of sensors, much beyond what is available today. Our work has centred on the enhancement...

At Waterloo, we are developing a high power, short pulse, two-color, Yb:fiber amplifier system to generate the long wavelength (>15μm) side of the molecular fingerprint spectral region, by difference frequency mixing the two colors. This spectral region is important for trace gas detection of explosives. As an example, it has been shown that the st...

We demonstrate that the giant chirp of coherent, nanosecond pulses generated in an 846 m long, all-normal dispersion, nanotube mode-locked fiber laser can be compensated using a chirped fiber Bragg grating compressor. Linear compression to 11 ps is reported, corresponding to an extreme compression factor of . Experimental results are supported by n...

We discovered an experimental artifact that fit our measurement of the broad band cavity mode. This artefact casts doubt on the proposed concept and brings the need of further investigation.

We demonstrate two novel types of applications using the same generator as a source for Brillouin multi-wavelength generation. The first is as a highly flexible picosecond pulsed laser source which is tunable in time duration, repetition rate and emission wavelength for optical clock applications in telecommunication. The second application is a hi...

We present a novel cavity using chirped fiber Bragg gratings in which an oscillating mode's wavelength dependency is eliminated making it a broad-band mode. Unlike a Fabry-Perot resonator, this cavity has no frequency constraints within the operating bandwidth.

We show how a novel all-fiber sensor system can be used to increase the Brillouin scattering temperature and strain sensitivity by the order of the stimulated Stokes wave used for distributed sensing in optical fiber.

Fabry-Perot resonators or interferometers (FPI) have existed for a long time and act as light accumulators. However, their applications have been limited to the allowed resonance modes in the cavity, which are defined by the specific free-spectral range of the FPI. We show here a novel concept involving a light “capacitor” capable of accumulating l...

In an effort to reduce the cost of sensing systems and make them more compact and flexible, Brillouin scattering has been demonstrated as a useful tool, especially for distributed temperature and strain sensing (DTSS), with a resolution of a few centimeters over several tens of kilometers of fiber. However, sensing is limited by the Brillouin frequ...

Although Yb:YAG has been cooled in a vacuum environment1, we report for the first time an experimental demonstration of optical cooling at atmospheric pressure. A Yb:YAG crystal is supported on thin silica fibers, inside a matt-black chamber with air at atmospheric pressure, and pumped at 1029 nm in the pulsed and CW regimes. Direct measurement of...

The fabrication and characterization of high quality ultra-long (up to 1m) fiber Bragg gratings (FBGs) is reported. A moving phase mask and an electro-optic phase-modulation (EOPM) based interferometer are used with a high precision 1-meter long translation stage and compared. A novel interferometer position feedback scheme to simplify the fabricat...

We report for the first time the experimental demonstration of optical cooling of a bulk crystal at atmospheric pressure. The use of a fiber Bragg grating (FBG) sensor to measure laser-induced cooling in real time is also demonstrated for the first time. A temperature drop of 8.8 K from the chamber temperature was observed in a Yb:YAG crystal in ai...

This paper presents our recent progress in the generation of tunable ultra-short pulses using higher order stimulated Brillouin scattering (SBS) in optical fibres for applications in optical transmission and clock generation at variable repetition rates.

We have developed a new system to generate GHz repetition rate tunable pulses in the picosecond regime at any wavelength by using self-phase-locked stimulated Brillouin scattering (SBS). The phase-locked comb at any required wavelength is generated using a single length of fiber in a ring cavity, seeded by an amplified single frequency CW pump lase...

We show for the first time to our knowledge, measurements of anti-Stokes fluorescence and lifetime measurements in quantum dot (QD) doped glass, which has been proposed as a potential material for optical refrigeration recently. The glass host studied here is known as SNAB (SiO2, Na2CO3, Al2O3, B2O3) and is doped with PbS QDs. We show that when exc...

ZBLAN fiber has been vastly investigated over the past decades since it has a broad wavelength transparent region. Therefore, to use it at its maximum potential in multiple applications such as in fiber lasers, amplifiers, laser cooling or infrared super continuum generation, it is important to know its intrinsic material properties. We have invest...

We show how a novel all-fiber sensor system can be used to increase the Brillouin scattering temperature and strain sensitivity by the order of the stimulated Stokes wave used for sensing.

We propose a new method to generate high frequency phase-locked tuneable pulses in the ps regime by using a Stimulated Brillouin Scattering frequency comb in single mode fiber at any wavelength.

Theoretical schemes for laser cooling with nanoparticles have been presented and comprehensively investigated. It is shown that specially designed samples based on nanoparticles can be used to improve the process of laser cooling of solids. One of the proposed schemes is based on lead salt colloidal quantum dots (QDs) doped in a glass host. The sec...

We propose a method to generate phase-locked pulses in the picosecond regime by using Stimulated Brillouin Scattering (SBS). The phase-locked comb is generated using only long length of fiber and a single frequency CW pump laser. We show that there is a phase relationship between multiple Stokes peaks in a cavity, which directly leads to pulsing wi...

The PolyProject initiative goal is to produce a low cost dataglove for sign language translation by using an optical detector technology and a 3D positioning system. The main innovation here is the optical system used for the glove which allows a great cost reduction. The glove also makes sign language translation much more accessible. In this arti...

The feasibility of extended exploration and human presence on the Moon and Mars depends critically on dealing with the environmental factors, especially the intrusive effects of dust. The prior Apollo landed missions found that the lunar dust exhibited high adherence to exposed surfaces and a restrictive friction-like action causing premature wear...

Sensory gloves are promising technologies for human/machine interface and sign language translation. For theses applications, all degrees of freedom of the human hand have to be monitored with a good precision. For now, there is no sensory glove on the market meeting these requirements at low cost for widespread consumer applications. This paper de...

We present measurements and characterization of stimulated Brillouin scattering (SBS) in multi-mode fiber (MMF) in comparison with single-mode fiber (SMF). As can be expected, the threshold for SBS was measured to be much higher in MMF (105 mW) compared with SMF (15 mW). A difference of 525 MHz was observed in the SBS frequency shift between both t...