Institut National D'optique

Universitè Laval

Claude Pare

Serge Caron

Pierre-Andre Belanger

Alain Chandonnet

Richard L Lachance

Vincent Roy

Richard Van Neste

André Fougeres

Antoine Proulx

Yves Champagne

Bruno Bourliaguet

Michel Fortin

Huimin Zheng

Liya Muslinkina

Lia Mouslinkina

Jean-Francois Cormier

Andre Croteau

An optical fiber polarimetric chemical sensor for capillary gas chromatography in which a sample fluid is injected into a capillary in the form of a periodic pulse train. Each individual pulse defines a moving polarization coupling zone that affects the polarization state of the light propagating in a birefringent optical waveguide that includes the capillary. The spacing between consecutive coupling zones can be made equal to the polarization beat length of the waveguide when the injection frequency of the pulses is properly selected, thus defining a resonance condition for a given analyte. The contributions of the successive coupling zones present along the length of the capillary then add up in phase, thus resulting in a detected optical signal having an enhanced amplitude peak at the injection frequency. In this manner, the sensitivity can be enhanced.

Optical fiber polarimetric chemical sensor with modulated injection of sample fluid

An apparatus and method for analyzing a fluid with particle analytes, where the fluid is fed through a passageway within an optical fiber and excitation light is guided by the optical fiber across the passageway and intersects the fluid therein. The optical core is made multimode and is adapted to shape the excitation light with a uniform spatial illumination over a cross-section of the optical core and the passageway is configured relative to the optical core such that the particle analytes are exposed to substantially equal excitation light while circulating in the passageway.

Flow cytometry analysis across optical fiber

There is provided an evanescent wave multimode optical waveguide sensitive to a chemical species or to a physical parameter. The optical waveguide comprises a core and a cladding having a cladding refractive index lower than that of the core for guiding light to be propagated in the optical waveguide. The cladding defines with the core an optical waveguide providing mode coupling. A chemical indicator is provided in the cladding for causing a variation of the optical absorption of the cladding as a function of the chemical species or the physical parameter. The cladding is interrogated by the evanescent wave of the propagated light. The mode coupling causes unabsorbed light power to be redistributed among the multiple modes while light propagates along the optical waveguide.

Evanescent wave multimode optical waveguide sensitive to a chemical species and/or a physical parameter and provided with continuous redistribution of optical power between the modes

Evanescent wave multimode optical waveguide sensor with continuous redistribution of optical power between the modes

The present invention relates to an apparatus and a method upon which the apparatus is based for direct optical measurement of first and second moments (variance) of two-dimensional continuous-wave optical beam irradiance distributions. The apparatus and method are based on an optical filter having a spatially-varying transmittance or reflectance profile described by a one-dimensional truncated parabolic function. The light power transmitted through or reflected by the optical filter is measured by a photodetector as the optical filter travels horizontally across the beam irradiance profile. The variance is obtained from the ratio of the peak signal given by the photodetector normalized to the signal corresponding to the total optical power of the unobstructed optical beam. The first moment in a fixed reference frame is given by the horizontal position of the region of peak transmittance/reflectance of the filter when the maximum signal is measured.

Apparatus for measuring a beam width D.sub..sigma.x along a transverse

A process for making a custom phase-conjugated circular mirror to be used in a laser resonator that will suit specifications of a user is provided. The mirror reverses wavefront of one particular input beam .PSI..sub.o (x) determined by the user, the input beam .PSI..sub.o (x) having a given wavelength, the laser resonator including the mirror and an output coupler cooperating with the mirror and separated therefrom by a laser gain medium, the mirror being at a distance L from the output coupler. The process comprises steps of (a) determining the input beam .PSI..sub.o (x) that will suit need of the user; (b) calculating equation of .PSI..sub.L (x) which is a value of the input beam .PSI..sub.o (x) that is propagated through said laser gain medium at distance L; (c) calculating phase .PHI..sub.o (x) of the input beam, which is a phase of the input beam .PSI..sub.o (x) at distance L, the phase .PHI..sub.o (x) determining profile of the custom phase-conjugated mirror; and (d) fabricating the custom phase-conjugated mirror according to the profile determined in step (c), whereby a custom phase-conjugated mirror can be provided to suit the specifications of the user. There is also provided a mirror made according to the above-mentioned method.

Process for making a custom phase-conjugated circular mirror to be used

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Saint-Augustin-de-Desmaures, Canada

Claude Pare