Universitè Laval

Institut Franco-allemand De Recherches De Saint-louis

Réal Vallée

Martin Bernier

Vincent Fortin

François Trépanier

Frédéric Maes

Simon Duval

Yigit Ozan Aydin

Souleymane Toubou Bah

Julien Carrier

Sophie Larochelle

Dominic Faucher

Charles Matte-breton

Érik Belanger

David Helie

Bertrand De Dorlodot

Fabrice Lacroix

Jean-Christophe Gauthier

Pierre Marquet

Francois Trepanier

There is described a method for determining a refractive index of a medium. The method generally has providing a substrate having a surface, the surface having a first surface portion and a second surface portion spaced-apart from the first surface portion and recessed of a depth relative to the first surface portion; receiving the medium at least on the second surface portion; propagating a first optical beam towards the first surface portion and a second optical beam towards the second surface portion; collecting the first and second optical beams after said propagating and generating first and second signals being indicative of a phase of a respective one of the first and second collected optical beams; and determining a refractive index of said medium based on the first and second signals, the depth, a wavelength associated to the first and second optical beams and a refractive index of the substrate.

System and method for measuring a refractive index of a medium

Mid-infrared-transparent optical fiber products with enhanced resistance to OH diffusion are disclosed, which may be used fiber laser oscillator and amplifiers systems. In one embodiment, an optical fiber product may include optical fiber configured for propagation of mid-infrared radiation toward a light-radiating endface of or coupled to the optical fiber, and a diffusion barrier disposed on the light-radiating endface and configured for allowing the mid-infrared radiation emanating from the light-radiating endface to pass therethrough and for preventing OH diffusion therethrough toward the light-radiating endface. In another embodiment, an optical fiber product may include an optical fiber for propagation of mid-infrared radiation and an endcap coupled to the optical fiber for receiving therefrom the mid-infrared radiation and radiating out the mid-infrared radiation, the endcap being made of an endcap material that has no or a low amount of fluoride and that is less permeable to OH diffusion than the fiber-optic material.

Mid-infrared optical fibers with enhanced OH-diffusion resistance

There is described a method of optically coupling a first optical fiber and a second optical fiber to one another. The method generally has a step of bringing a free end of the first optical fiber, the second optical fiber and liquid in close proximity to one another within a coupling region, the free end of the first optical fiber having a dimension below a critical dimension, the free end of the first optical fiber moving within said liquid to contact the second optical fiber along a given coupling length, said contact optically coupling the free end of the first optical fiber and the second optical fiber to one another.

Method of coupling optical fibers, and optical coupler

An optical fiber having a Bragg grating along a non-photosensitized grating region thereof and a pristine polymer coating around the grating region with the Bragg grating having been written through the polymer coating has a mechanical resistance that is greater than 20% of the mechanical resistance of an identical grating-free optical fiber.

Writing of high mechanical strength fiber bragg gratings using ultrafast pulses and a phase mask

Methods and systems for writing a Bragg grating along a grating region of an optical fiber through a polymer coating of the optical fiber are provided. A light beam of ultrafast optical pulses is impinged on the grating region, the ultrafast optical pulses being characterized by writing wavelength at the grating region to which the polymer coating is substantially transparent The light beam is diffracted through a phase mask so as to form an interference pattern defining the Bragg grating at the grating region of the optical fiber. The light beam is also focussed such that the intensity of the optical pulses is below a damage threshold within the polymer coating, and above an FBG inscription threshold within the grating region of the fiber. Optical fiber having Bragg gratings and improved mechanical are also provided.

Writing of high mechanical strength fiber Bragg gratings through the polymer coating of an optical fiber

The mid-infrared laser system has an amplifier including at least one pump laser adapted to generate a pump laser beam and a length of fiber made of a low phonon energy glass and having at least one laser-active doped region between a first end and a second end, and a seed laser to generate a seed laser beam having a seed optical spectrum in the mid-infrared. The seed laser beam is launched into the first end to generate a mid-infrared laser beam outputted from the second end via stimulated emission upon pumping of the at least one laser-active doped region with the pump laser beam. When the power of the pump laser exceeds a spectrum modification threshold, the mid-infrared laser beam has an output optical spectrum being broadened relative to the seed optical spectrum.

Mid-infrared laser system, mid-infrared optical amplifier, and method of operating a mid-infrared laser system

A method for writing a Bragg grating in a glass optical waveguide is provided. Ultrafast optical pulses are generated, preferably in the femtosecond range and having a writing wavelength in the range of 300 nm to 700 nm and an intensity sufficient to induce a change of refractive index in the waveguide through densification. The optical pulses are diffracted using a phase mask, to generate an interference pattern having a pitch providing a fundamental Bragg resonance corresponding to the target wavelength to be reflected by the grating. The interference pattern is impinged on a region of the waveguide, which is heated to a temperature above a threshold and for a predetermined heating period. Advantageously, the heating step allows the reduction of photoinduced losses which would otherwise be present in the waveguiding properties of the waveguide. Optionally, gratings may be written through the polymer jacket of an optical fiber.

Method for writing high power resistant Bragg gratings using short wavelength ultrafast pulses

A method for writing a Bragg grating in a rare-earth doped glass optical waveguide is provided. Ultrafast optical pulses are generated, preferably in the femtosecond range and having a writing wavelength in the range of 300 nm to 700 nm and an intensity sufficient to induce a change of refractive index in the rare-earth doped glass waveguide through densification. The optical pulses are diffracted using a phase mask, to generate an interference pattern having a pitch providing a fundamental Bragg resonance corresponding to the target wavelength to be reflected by the grating. The interference pattern is impinged on a region of the rare-earth doped glass waveguide, which is heated to a temperature above a threshold of about 350&#xb0; C., for a predetermined heating period. Advantageously, the heating step allows the elimination of photodarkening effects which would otherwise be present in the waveguiding properties of the waveguide.

Method for writing high power resistant bragg gratings using short wavelength ultrafast pulses

A system and method for permanently writing diffraction gratings in low phonon energy glass waveguides are shown. Ultrashort light pulses are generated and made to form two beams synchronously superimposed in the waveguide, therefore forming an interference pattern corresponding to the desired grating. The light pulses are focussed so that the light intensity in the waveguide exceeds a filamentation threshold. The exposure of the waveguide to these light pulses is controlled temporally and spatially in order to limit detrimental thermal effects induced by the high-intensity pulses in the glass medium of the waveguide.

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Québec, Canada

Réal Vallée